KINGDOM MONERA

Syllabus: Bacteria, Cyanobacteria, Mycoplasma, Actinomycetes, Rickettsia, Archaea, Chlamydiae, Virus

(As mentioned for AIPMT & MP PMT )
(1944) established the role of DNA as genetic material

Bacteria

by using transformation in bacteria as evidence.

Lederberg and Tatum (1946) described genetic
Recombination through bacteria conjugation.

What are Bacteria?

Until recently, the term bacteria was used for all
microscopic prokaryotes. But, it turns out that there
are two groups of prokaryotes that differ from each
other in just about every way except size and lack of a
nucleus.

Properties of Bacteria

prokaryotic (no membrane-enclosed nucleus)

no mitochondria or chloroplasts. Circular in foldings
of plasmamembrane are mesosomes.

These are now distinguished as the:

a single chromosome (Prochromosome).

Bacteria; the "true" bacteria (also known as

Eubacteria)

a closed circle of double-stranded DNA, known as

Genophore / Nucleoid / Incipient nucleus.

Archaea; (also known as Archaebacteria)

with no associated histones

The archaea are so different from the bacteria that they

must have had a long, independent evolutionary history
since close to the dawn of life. In fact, there is
considerable evidence that you are more closely
related to the archaea than they are to the b acteria.
Bacteria were first discovered by a Dutch (a resident
of Holland), Antony von Leeuwenhoek in 1676. He
observed them in a rain drop with the help of a simple

If flagella are present, they are made of a single

filament of the protein flagellin; there are none of the
"9+2" tubulin-containing microtubules of the
eukaryotes.

ribosomes differ in their structure from those of

eukaryotes

have a rigid cell wall made of peptidoglycan.

microscope designed by him. He also gave illustrated

account of these microscopic organism from his own
teeth scum. These were called animalcules by the
early microbioligists. It was linnaeus (1758) who
placed them under the genus vermes. The name
bacteria (bacteria; Greek = small stick was given to
these microorganisms by a German biologist Christian
G. Ehrenberg (1828). However, bacteria as a group
were recognized by a German botanist, Kart Willhelm

The plasma membrane is a phospholipid bilayer but

contains no cholesterol or other steroids.

no mitosis but amitosis

mostly asexual reproduction
any sexual reproduction very different from that of
eukaryotes; no meiosis

Many bacteria form a single spore when their food

supply runs low. Most of the water is removed from
the spore and metabolism ceases. Spores are so
resistant to adverse conditions of dryness and
temperature that they may remain viable even after 50
years of dormancy.

von Nageli (1857) who proposed the name

schizomycetes for this group. Some of the significant
events in bacteriology are listed below. Louis Pasteur,
a French chemist, observed that bacteria are the source
of some diseases. This fact was called Germ Theory
of Diseases. He also Discovered bacteria causing
chicken cholera. Almost at the same time Robert Koch
(1843-1910), A German physician, discovered bacteria
causing anthrax and tuberculosis. On the basis of his

Bacteria: More on Morphology

studies, he established certain criteria to decide

bacteria as cause of disease which were called Kochs
postulates. He was later awarded Nobel Prize in 1905
for his work. Joseph Lister (1878) who used carbolic
acid as disinfectant for antiseptic surgery for the first
time, also developed a method of cultivation of pure
cultures of bacteria. Avery, Macleod and McCarty

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A more or less typical bacterium, shown here, is

comparatively much simpler than a typical eukaryotic
cell. Bacteria lack the membrane-bound nuclei of
eukaryotes; their DNA forms a tangle known as a
nucleoid, but there is no membrane around the
nucleoid, and the DNA is not bound to proteins as it is
in eukaryotes. Whereas eukaryote DNA is organized
into linear pieces, the chromosomes, bacterial DNA
forms loops. Bacteria contain plasmids, or small loops
of DNA, that can be transmitted from one cell to
another, either in the course of sex (yes, bacteria have
sex) or by viruses. This ability to trade genes with all
comers makes bacteria amazingly adaptible; beneficial
genes, like those for antibiotic resistance, may be
spread very rapidly through bacterial populations. It
also makes bacteria favorites of molecular biologists
and genetic engineers; new genes can be inserted into
bacteria with ease. Bacteria do not contain membrane bound organelles such as mitochondria or chloroplasts,
as eukaryotes do. However, photosynthetic bacteria,
such as cyanobacteria, may be filled with tightly
packed folds of their outer membrane. The effect of
these membranes is to increase the potential surface
area on which photosynthesis can take place. The cell
membrane is surrounded by a cell wall in all bacteria
except one group, the Mollicutes, which includes
pathogens such as the mycoplasmas. The composition
of the cell wall varies among species and is an
important character for identifying and classifying
bacteria. In this diagram, the bacterium has a fairly
thick cell wall made of peptidoglycan (carbohydrate
polymers cross-linked by proteins); such bacteria
retain a purple color when stained with a dye known as
crystal violet, and are known as Gram-positive (after
the Danish bacteriologist who developed this staining
procedure). Other bacteria have double cell walls, with
a thin inner wall of peptidoglycan and an outer wall of
carbohydrates, proteins, and lipids. Such bacteria do
not stain purple with crystal violet and are known as
Gram-negative.

The beta-lactams all work by interfering with the

synthesis of the bacterial cell wall a structure that is
not found in eukaryotes. The walls of bacteria are made
of a complex polymeric material called peptidoglycan.
As its name suggests, it contains both amino acids and
sugars. The sugars are of two kinds a nitrogen containing hexose called N-acetylglucosamine (NAG)
and its close relative
N-acetylmuramic acid (NAM)
These two form a linear polymer of NAG alternating
with NAM. The links are between the #1 and #4 carbons
(this is the linkage attacked by lysozyme) and are
oriented in the same way they are in cellulose. Side
chains containing 4 or 5 amino acids are attached to
each NAM. These form covalent bonds with amino acids
in adjacent chains. The bonds may

be direct to the next chain or

include additional peptide cross bridges
(e.g., 5 glycine residues)
Staining of Bacteria
Hans Gram (1884), a Danish microbiologist,
introduced a specific stain for bacteria, now known as
Gram stain. This widely used stain differentiates two
types of bacteria, called Gram positive (Gram + ) and
Gram negative (Gram ) bacteria.

The Chink in the Armor = the bacterial cell wall

[I] The staining process

A bacterial smear is prepared on a clean slide. It is
stained with alcoholic crystal violet and then destained
with water. It is later treated with aqueous solution of
iodine (prepared by dissolving iodine and potassium
iodide in water). After sometime iodine is also washed
off with water. At this stage, all the bacteria appear
purple coloured. The smear is now destained with 95%
ethyl alcohol, till the stain stops to come out. The
distaining results in differentiation of two types of
bacteria- gram positive bacteria which retain the
purple colour and the gram negative bacteria which

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appear colourless. Gram negative bacteria are later

counterstained with safranin.

Bacteria can live both in the presence or absence of

oxygen. They can survive in extreme cold
( 17 C) and can also tolerate very high temperature
(80 C) and drought.

[II] Explanation of differential staining

Different response to Gram stain is due to difference
in the chemical composition of bacterial cell walls. In
gram negative bacteria most of the wall being made of
lipids, it gets dissolved when treated with alcohol and
allows leakage of crystal violet-iodine (CVI) complex.
In gram positive bacteria, wails have relatively less
lipids and hence there is less leakage of CVI complex.
Thus, these bacteria show purple or violet coloured
walls.

The presence of bacteria in variety of habitats is due to

(i) their resistant nature, (ii) characteristic modes of
nutrition and (iii) formation of resistant endospores.
Shape of Bacteria
There are more than 2000 species of bacteria known
to-date. Following four fundamental shapes are
recognised.
[I] Bacillus or rod-shaped
These are small stick or rod-shaped bacteria (Fig.l).
This shape is the commonest of all the bacterial
shapes. Bacilli may occur in the following two forms.
1. Diplobacillus: In this form two or more bacilli
occur in pair; e.g., Corynebacterium diphtheriae.
2. Streptobacillus: In this type many bacilli occur in
a chain, e.g., Bacillus tuberculosis, Bacillus anthracis,
etc.
[II]

Coccus or spherical

These bacteria are oval or .spherical in shape (Fig. 1).

Cocci are generally non-motile and are the smallest
amongst all known bacteria. Cocci occur in the
following forms.
Differences between Gram
Gram Negative Bacteria
Gram positive
1.
The
amount
peptidoglycan is more.

Positive

1. Micrococci: In this type each coccus is a free

individual; e.g., Micrococcus luteus, etc.

and

2. Diplococcus: Here cocci remain attached, mostly

in pairs; e.g., Diplococcus pneumonias, etc.

Gram negative
of 1.
The
amount
peptidoglycan is less.

of

3. Streptococcus.
In
this
e.g., Streptococcus lactis, etc.

2. Only a few types of 2. The types of amino acids

amino acids are present.
are more.
3. Teichoic acid present.
3. Teichoic acid absent.
4. Low in lipids (l.4%).
4. High in lipids (11-22%).
5. Cell wall 100-250 5. Cell wall 75-120 thick.
thick.
6. Cell wall rigid.
6. Cell wall elastic.
7. Mesosomes present.
7. Mesosome
rare or
absent.
8. Ratio of RNA to
8. Ratio of RNA to DNA
DNA 8:1.
almost equal,
9. Highly susceptible to
penicillin.

4. Tetracoccus or tetrad. Here four cocci form a

characteristic group; e.g., Neisseria, etc.
5. Staphylococcus. Here cells form irregular groups
or bunches; e.g., Staphylococcus aureus, etc.
6. Sarcinae. Here 8-64 cocci are arranged in cubes; e.g.,
Sarcina lutea, etc.
[III] Spiral or helical
These bacteria are helical or cork screw shaped or
coiled (Fig. 1); e.g., Spirillum volutans, etc.

9. Relatively less
susceptible.

[IV] Some other shapes

Distribution of Bacteria

Besides the shapes of bacteria mentioned above, some

other shapes are as follows.

Bacteria are found in almost all the habitable place.

They are widely distributed in air, water and land.
Large number of bacteria also occur in animal and
human bodies.

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type cocci form chain;

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1. Comma-shaped: These are short, incomplete

spirals and look like comma (,) (Fig. 1). They
are also known as Vibrio; e.g, Vibrio choleras.

pneumosintes is probably the smallest (length 0.15-0.31

m) bacterium known.
Special groups of bacteria

2. Stalked rods: These are rod-shaped with a

distinct stalk (Fig. 1); e.g., Caulobacter.

1. Rhizobia: These bacteria live in a mutualistic

relationship with the roots of legumes where they are
able to "fix" nitrogen (N 2 ) in the air into compounds
that can be used by living things.

3. Branched filament : The bacterium is long and

thread-like (Fig. 1); e.g., Streptomyces.
4. Pleomorphic: The shape of many bacteria
changes according to time, habitat and medium. This
character of existence of different shapes in the same
species is called pleomorphism; e.g., Azotobacter,
etc.

2. Sulfur bacteria:
Certain colorless bacteria share the ability of
chlorophyll-containing organisms to manufacture
carbohydrates from inorganic raw materials, but they do
not use light energy for this. These so -called
chemoautotrophic bacteria secure the necessary energy
by oxidizing some reduced substance present in their
environment. The free energy released by the oxidation
is harnessed to the manufacture of food. For example,
some chemoautotrophic sulfur bacteria oxidize H 2 S in
their surroundings (e.g., the water of sulfu r springs) to
produce energy:

bacillus-rod shaped bacteria

2H 2 S + O 2 2S + 2H 2 O; G = -100 kcal
They then use this energy to reduce carbon dioxide to
carbohydrate (like the photosynthetic purple sulfur
bacteria).

coccus-spherical bacteria

2H 2 S + CO 2 (CH 2 O) + H 2 O + 2S
3. Iron bacteria: These chemoautotrophs are responsible
for the brownish scale that forms inside the tanks of flush
toilets. They complete the oxidation of partially oxidized iron
compounds and are able to couple the energy produced to the
synthesis of carbohydrate.
4. Nitrosomonas: This chemoautotroph oxidizes
NH 3 (produced from proteins by decay bacteria) to
nitrites (NO 2 - ). This provides the energy to drive their
anabolic reactions. The nitrites are then converted (by
other nitrifying bacteria) into nitrates (NO 3 - ), which
supply the nitrogen needs of plants.
5. Purple Sulfur Bacteria: Like green plants, these
bacteria are photosynthetic, using the energy of sunlight
to reduce carbon dioxide to carbohydrate. Unlike plants,
however, they do not use water as a source of electrons.
Instead they use hydrogen sulfide to supply the
electrons needed to synthesize NADPH and ATP.
2H 2 S + CO 2 (CH 2 O) + H 2 O + 2S

Fig.1. Bacterial cells : Different- shapes.

Size of Bacteria:

In the process, they produce elemental sulfur

Bacteria vary considerably in size. The average size of

a bacterial cell is 0.5 - 1.0 x 2.0-5.0 m. Beggiatoa
mirabilis is the largest bacterium (16-45 m). Bacillus
butschlii , with a length of approximately 80 m is
considered to be the longest bacterium. Dialister

In Chromatium - stored as granules within the cell.

Photosynthetic bacteria contain special types of
chlorophylls (called bacteriochlorophylls) incorporated
into membranes. With this machinery, they can run
photosystem I but not photosystem II (which explains
their inability to use water as a source of electrons).

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1. Binary fission: This is the commonest and the most

important method. In this process the cell elongates
followed by formation of transverse wall (Fig. 5). This
results in the production of two daughter cells. Each
daughter cell grows into a new bacterium. Thus with
every division the number of bacteria cells becomes
double. Under favourable conditions, a cell of
Eschrichia coli divides by fission, every 15 to 20
minutes. This is called generation time. The cells
increase in number until their waste products
accumulate to limit further growth or until come
essential nutrient is exhausted.

Most photosynthetic bacteria are obligate anaerobes

they cannot tolerate free oxygen. Thus they are
restricted to such habitats as the surface of sediments
at the bottom of shallow ponds and estuaries. Here
they must make do with whatever radiant energy gets
through the green algae and aquatic plants growing
above them. However, the absorption spectrum of their
bacteriochlorophylls lies mostly in the infrared region
of the spectrum so they can trap energy missed by the
green plants above them.
Chemotaxis
When a capillary tube filled with glucose is placed in a
medium containing E. coli, the bacteria alter their
locomotion so that they congregate near the opening of
the tube. This chemotactic response does not depend
on the bacteria being able to metabolize the substance
although presumably that is the value under normal
conditions. E. coli responds strongly to a number of
organic molecules besides glucose, including galactose
and the amino acids serine and aspartic acid.

2. Budding: In this process, the cell produces

outgrowth called buds, Cytoplasm and the chromatin
material also enter the bud which later separartes from
the parent cells by constriction. The separated bud takes
the form of new bacterial cell. Budding is commonly
observed in the genus Hyphomicrobium.
[II] Asexual reproduction
The most common method of asexual reproduction is
the formation of endospores. However, conidia,
zoospores and cysts are also formed in a few species. Of
these, endospores are organs of perennation rather than
reproduction.

Phototaxis
Photosynthetic
microorganisms
often
display
phototaxis. This is a positive phototaxis. However, as
the intensity of the light is increased, a point is
reached where they abruptly reverse direction and
swim away from the light (a negative phototaxis).

1. Endospore: In bacteria like Clostridium, Bacillus,

etc, cell produces a resistant structure called endospore.
Only one endospore is produced per cell (Fig. 6A).

Magnetotaxis

The endospre formation begins with the invagination of

cell wall (Fig. 6B) followed by invagination of the cell
membrane. It encloses a part of the protoplasm. Outside
this cell membrane, a region called cortex is formed
outside the cortex spore coat consisting of several layers
is formed. Outermost part of the spore is exosporium
which lies outside the spore coat. The cortex of the
endospre is a complex of calcium, dipiocolinic acid and
peptidoglycan, a characteristic feature of bacterial
endospores only. This complex forms about 5 - 10% of
the dry weight of the endospore and is responsible for
the resistance of endosopore to different extremes of
physical and chemical forces. Cytoplasm, ribosomes and
DNA are also found in the endospore. Th e endospore
are smaller than the parent cell. According to the place
of their formation, these are known as central terminal
or subterminal. Under unfavourable conditions,
endospores remain dormant. On the return of favourable
condition, the spore caot breks open and a new
bacterium is produced. Thus, endospores are organs of
perennation which tide over the unfavaourable
conditions.

Several species of bacteria swim in the direction of

magnetic lines of force. Example:

Magnetospirillum magnetotacticum. The row of dark

objects within the cell are particle of magnetite
(FeO . Fe 2 O 3 ). These act like a compass needle, and in
this species, which was found in a freshwater pond in
New Hampshire (USA), orient themselftoward the
North Pole.
Reproduction in Bacteria
Bacteria reproduce by (i) Vegetative (ii) asexual and
(iii) genetic recombination or sexual methods.
[I] Vegetative reproduction

2. Conidia: In some bacteria (e.g., Streptomyces) the

filament divides transversely into small cells. These
transform into a chain of conidia.

Fission and budding are the two common methods of

vegetative reproduction.

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3. Zoospores: This is a common method of asexual

reproduction in Rhizobium which produces flagellated
zoospores.

called transducing particles) bring about transduction.

However, the order phage particles without such
bacterial DNA are incapable of transduction.

4. Cyst: In Azotobacter, thick walled spores, similar

to endospores, are formed, these are called cysts.

3. Conjugation: In contrast to transduction and

transformation, conjugation involves direct contact
between donor and recipient bacteria. The process was
discovered in
1946 by Lederberg and Tatum in
Escherichia coli, a common human colon bacterium, It
synthesizes all amino acids essential for it, provided
glucose and minerals are available. But Lederberg and
could not synthesize one or the other amino acid. when
large number of these two stains were ability to
synthesize all the amino acids they needed. this could
not have been possible without the transfer of genetic
material from one bacterium to another. Later in 1956,
Wollman, Jacob and Hayes worked out the details of
the process, they showed that genetic material is
transferred from donor to the recipient cell through a
cytoplasmic bridge which is formed after chance
collision and surface contact. Escherichia coli shows
sexual differentiation. Male cells (also called donor
cells) contain a fertility, sex or F-factor on their
chromosome. Hence, male cells are also known as F +
cells or fertile cells, they serve as donors during
conjugation. Female cells (also called recipient cells)
lack F-factor and represented as F . F-factor, like any
other genetic material, is in fact a piece of DNA. It
exists in the cytoplasm (of male cells) either as an
autonomous element (i.e., episome) or may be
integrated into the chromosome of the bacterial cell. the
latter condition is known as Hfr (high frequency of
recombinant). During conjugation a copy of the F -factor
from donor (male) cell is transferred to the recipient
(female) cell. As a result the F cell (i.e., female) is
changed into F + cell (i.e., male cell).

[III]
Sexual
recombination

reproduction

or

genetic

Sexual reproduction in bacteria does not involve

production of gametes and their subsequent fusion.
Instead, genetic recombinations, similar to those
resulting from normal sexual reproduction, are
produced but by different processes. The processes of
genetic
recombination
in
bacteria
include
transformation, transduction and conjugation.
1. Transformation: This process in bacteria was
demonstrated by Griffith, a British medical officer in
1928. In this process the donor and the recipient
bacterial cells do not come in contact. Griffith, while
working on the pneumonia causing bacterium
(Diplococcus pnumonia), came across two strains rough or R-cell and smooth or S-cells. The R-cells
were avirulent (i.e., non- pathogenic) and had no
capsules whereas the S- cell were virulent (i.e.,
pathogenic) and capsulated. He injected a mouse with
living R-cells (non-pathogenic) of pneumococcus. He
observed that the mouse died mouse showed the
presence of living S-cells, beside R-cells. He,
therefore, concluded that dead S-cells had released in
the transformation of R-cells into virulent (pathogenic)
forms, thereby killing the host. This transforming
factor was later identified as DNA by Avery, Macleod
and Mc Carty in 1944. The process of transformation is
now very well understood. During this process a short
piece of DNA, containing one or more genes, is
released by the donor cell (in the medium). It enters
the recipient cell and recombinants are formed.

Economic Importance of Bacteria

The bacteria are mostly known to be harmful since they
produce many serious diseases. On the other hand, their
importance in the industry, antibiotics and natural
recycling of material can not be ignored. As such,
bacteria are both friends and foes of the human race.

2. Transduction: It is the process in which the

genetic material is transferred from donor to the
recepient bacterium by a bacteriophage (a virus that
infects bacteria is known as bacteriophage. The
process was discovered in the bacteriophage has an
outer protein coat and an inner DNA core. Th e phage
attaches itself to the bacterial cell and the DNA of the
phage particle is transferred to the bacterial cell. Once
inside the bacterial cell, the phage DNA starts
synthesizing new phage components. Meanwhile the
bacterial DNA also gets fragmented and these
segments are incorporated in some of the new phage
particles. Such phage particles with genes of bacterial
cell, when attack another bacterium, transfer the genes
carried from the earlier bacterium to this bacterium
and the recombination occurs. Thus phage particles
with genes (DNA) of bacterium first attacked (now

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[I] Useful activities

Following are some of the useful activities of bacteria.
1. Soil fertility: Bacteria participate most actively in
nitrogen fixation. They increase soil fertility by
converting molecular nitrogen of the atmosphere into
two groups-(i) free living or asymbiotic bacteria which
occur in the soil and fix nitrogen directly; e.g.,
Azotobacter, Clostridium, etc. and (ii) symbiotic
bacteria e.g., Rhizobium leguminosarum, Besides some
other plants.

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2. Nitrifying bacteria: These bacteria convert

ammonia to nitrate. This process involves two steps. in
the first, ammonia is converted into nitrite( NO 2 ) by
Nitrosomonas while in the second step the nitrite is
converted into nitrate (NO 3 ) by Nitrobacter.

Bacteria and Industrial Products/Processes

Products/
processes
1.
Preparation
Acetone-butanol

3. Ammonification: Ammonifying bacteria convert

protein into ammonia. The proteins are generally the
dead remains of the plants and animals, Such bact eria
are, therefore, also called bacteria of decay or
putrefying bacteria; e.g., Bacillus mycoides, B.
ramosus B. vulgaris, etc.
4. In food chains: Bacteria act as decomposers and
convert the complex organic substances to simple
substance. Thus they play an important role in the
recycling of materials, their activity is largely
responsible for accumulation of nutrients in the soil.
5. In dairy. Various types of bacteria are found in the
milk, these convert lactose sugar of the milk into lactic
acid which sores the milk.

Streptococcus lactis

2. Butter milk

Streptococcus lactis,
S. cremoris.

3. Cheese

Lactobacillus lactis

4. Curds

Streptococcus lactis,

Acetobacter aceti

3.
Manufacture
lactic acid

Lactobacillus delbrueckii

of

4. Production of lysine

Micrococcus glutamicus

5. Retting or fibres

Clostridium butyricum

6. Curing of Tobacco

Bacillus megatherium

7. Curing of tea

Mycococcus condisans

8. Symbiosis in human intestine: Escherichia coli

is a common colon bacterium found in human beings
and many vertebrates, this bacterium is normally not
harmful but is mostly helpful in digestion.

Lactobacillus bulgaricus,
Streptococcus
thermophilus

9. In ruminate animals: In these animals, rumen is

They coagulate protein casein to form curd. The

preparation of cheese is based on this principle. The
bacteria involved in the above fermentation process are
Streptococcus
lactis,
Lactobacillus
casei,
L.
acidophilous, etc.

inhabited by cellulose digesting bacteria like

Ruminococcus albus, Ruminate animals eat grass but the
cellulose is digested only by the ruminate b acteria
present in them.
10. Sewage disposal: Fecal matter collected in
sewage tanks indigested by a number of aerobic

Bacteria useful in the production of some dairy

products are given in the table 2.
6. in other industries. Many useful products of
economic importance are manufactured by using
bacteria, Some of them are listed in Table. 3.

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2.
Preparation
of
acetic acid or vinegar

broad spectrum, i.e., they act on a variety of pathogenic

micro-organisms. Some of the common and important
antibiotics are listed in Table. 4.

Lactobacillus, etc.
5. Yoghurt

Clostridium acetobutylicum

micro-organism which are detrimental or inhibitory to

other micro-organisms in very small amounts.
Antibiotics cure disease by competitive inhibition and
are obtained mostly from bacteria. However, the first
antibiotic, penicillin discovered
by sir Alexander
Flemming in 1929, was obtained from a fungus
Penicillium notatum. Some of the antibiotics are
specific (narrow spectrum antibiotics) while others are

Bacteria

1. Butter

of

7. Antibiotics: These are metabolic products of one

Some Milk products and Bacteria

Products

Bacteria

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1. Food poisoning. Numerous bacteria are found in

the food preparations. Some of these excrete toxic
substances and cause food poisoning, e.g., Clostrdium
botulinum (caused botulism), Escherichia, Micrococcus
pyogenes,
Salmonella
typhimurium
(produces
salmonellosis), etc.

Antibiotics and Bacteria

Antibiotic

Bacteria

1. Bacitracin
2. Polymyxin B

Bacillus subtilis
Bacillus polymyxa

3. Streptomycin

Bacillus griesus

4. Chloramphenicol
(Chloromycetin)
5. Chlortetracycline
(Aureomycin)
6. Erythromycin
7. Griesofulvin
8. Kanamycin

Streptomyces venezuelae

9. Neomycin

S. fradiae

10. Terramycin
(Oxytetracycline)

S. rimosus

2. Denitrification. Some bacteria like Bacillus

denitrificans, Thiobacillus denitrificans, etc., release
free nitrogen from nitrates present in the soil. Thus they
reduce soil fertility as plants can not use free nitrogen.
It can be utilised by them only in nitrate for m.

S. aitreofadens
S. erythraeus
S. griesus
S. kanamyceticus

3. Human diseases. Many bacteria are parasites

which infect the human body and cause various
diseases. Some of the diseases
are
listed
in
table 5.
4. Plant diseases. Many serious plant diseases
are caused by bacteria. Some important diseases
are given below

and anaerobic bacteria. In this process methane and

CO 2 are produced. Of these, methane is used as biogas,
whereas CO 2 is used by certain algae present in the
tank for photosynthesis, oxygen released by algal
photosynthesis is used in the oxidation of sewage,
thus, sewage tank or pond is an example of algal bacterial symbiosis

Disease

11. Genetic engineering: One of best materials for

work on genetics and molecular biology is Escherichia
coli. Genetic engineering is associated with direct
manipulation of individual genes. The transfer of
human insulin gene into bacteria has been one of the
great feats of genetic engineering. Diabetic mellitus is
caused due to shortage of human insulin and the
sufferers are forced to use insulin extracted from
salaughtered animals. Insulin is a protein and it was
thought that if the genes for this protein could be
inserted into a bacterium, these could be cultured to
serve as a cheap commercial source, Despite the
problems of transferring genes from eukaryotic cell to
prokaryotic cell successful transfer of human insulin
gene has now been achieved and commercial
production of insulin has already started. Another
useful human protein is the anti viral agent called
interferon, normally produced in response to viral
infections. Transfer of interferon gene into bacteria has
been accomplished. Thus, it appears possible to use
bacteria to manufacture large number of eukaryotic
products such as hormones, antibiotics, enzymes, etc.,
using plasmids as a convenient tool of gene transfer.

Scientific name Type

Shape

1. Cholera

Vibrio cholerae

Gram , comma

2. Diarrhoea

Bacillus coli

Gram +,
bacillus

3. Diphtheria

Corynebacterium
diphtheriae
Shigella dysentry

Gram + , bacillus

4. Dysentry
(Bacillary
dysentry)

Gram ,
bacillus

5. Gastroenteritis Escherichia coli

6. Gonorrhoea
7. Jaundice

8. Leprosy
9. Meningitis
10. Plague
11. Pneumonia
12. Syphilis
13. Tetanus
14. Tuberculosis
15. Typhoid

16. Whooping
cough
[II] Harmful activities
Following are some of the harmful activities of
bacteria.

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Causal bacteria

Page 8

Neisseria
gonorrhoeae
Leptospira
icterohaem
orrhagiae
Mycobacterium
leprae
Neisseria
meningitidis
Pasteurella pestis
Streptococcus
pneumoniae
Treponema
pallidum
Clostridium tetani
Mycobacterium
tuberculosis
Salmonella typhii
(= Eberthella
typhosa)
Bordetella
pertussis
(= Bacillus haemo
philus influenzae)

Gram , bacillus
Gram , coccus
Gram

,spirillum
Gram + , bacillus
Gram , cocci
Gram , bacillus
Gram + , cocci
Spirochaete
Gram + , bacillus
Gram + bacillus
Gram , bacillus
Gram ; bacillus.

Bacteria and Plant Diseases

Disease

Host plant

1. Angular leaf
spot

Gossypium spp. Xanthomonas

malvacearum
gram
Capsicum
Xanthomonas
annuum
vesicatora gram

2. Leaf spot

Causal bacteria

3. Blight of paddy Oryza saliva

Xanthomonas
oryzae gram

4. Bean blight

Phaseotus spp.

Xanthomonas
phaseoli indicus
gram

5. Citrus canker

Lemon, orange, Phytomonas citri

etc. (Citrus
gram
spp.)

6. Fire blight

Members of
famil
Rosaceae, e.g.,

7. Red stripe of Pyrus mains

sugarcane
Saccharum
officinarum

Erwinia
amylovora gram

Pseudomonas
rubrilineans
gram

8. Soft rot

Carrots, turnips,
etc.
Erwinia
carotovora gram
9. Tundu or
Triticum
bacterial rot
aestivum
Corynebacterium
tritici gram +
Preservation of Foods
The foods useful in daily life get spoiled due to
bacterial contamination. Some of the common methods
for protecting the food from bacteria are given below.

[III] Low temperature storage

[I] Canning

The food substances kept in the refrigerator \ (5C) and

freezer (5C) remain unspoiled for long period. Low
temperature does not kill the bacteria but reduces their
metabolic activities and growth to the negligible. In
cold storage the temperature is about 10C to 18C at
which bacterial activities are completely inhibited.
Some of the bacterial cells are even destroyed while
endospores remain alive but inactive. The rates of their
biochemical processes like respiration, absorption, et c.,
are at their lowest. Vegetables, juices of fruits, eggs,
meat, fish, etc., can be preserved by this method.

The food articles are steamed at 120 to 126C under

15 Ibs pressure for 12 to 90 minutes and then packed
in tin cans. During this period bacteria, then endospores and also all other living organisms are
killed.
[II] Pasteurization
This method was first used by Louis Pasteur in 1866.
There are two practices (i) the low temperature
holding method (LTH) where milk is heated to 145 F
(62.8C) for 30 minutes, and (ii) high temperature
short-time method (HTST) where milk is heated to
161F (71.7C) for 15 seconds. The finished product is
stored allow temperature to retard the growth of
microorganisms which survived pasteurization. The
above treatment kills bacteria causing typhoid, scarlet
fever, tuberculosis, etc., and many other nonendospore forming bacteria.

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[IV] Dehydration
Dehydration of meat, fish, vegetables, fruits, etc.,
reduces the water content of these articles and
bacterial growth is completely checked. Reduction of
water content to even 10% checks bacterial growth in
meat, fish, milk, etc., and fruits and vegetables remain
preserved if water content is less than 20%.

Page 9

(b) Heterocystous: They have differentiated trichome, e.g., Nostoc, Rivularia. In Schizothrix more
than one trichomes are found in the same sheath of a
filament. In Stigonema, a filament may have a few or a
multi-seriate trichome (in which numerous filaments
are associated in a common sheath).

[V] Preservatives
Pickles, jams, jellies, etc., can be preserved by
adding salt or sugar. By doing so bacteria get
plasmolysed and subsequently killed. In this way
these food articles can be preserved from bacterial
contamination. Chemical preservatives such as
ascorbic acid, benzoic acid, propionic acid, etc., are
commonly used as preservatives.
Cyanobacteria:
Introduction
Cyanophyta
include
the
class-cyanophyceae
(Myxophyceae) which further includes cyanobacteria
that contains true chlorophyll and bluish green
pigment C-phycocyanin. Name cyanobacteria has been
given by Eehlin and Morris.

Classification :
On the basis of morphology, motility, reproduction
and capacity of N 2 fixation Cohen Bazire, classified
cyanobacteria into four groups:
1. Chroococcacean: e.g., Microcystis, Chroococcus,
Gloeocapsa, etc.
2. Pseudocapsalean : e.g., Democarpa.
3. Oscillatorian : e.g., Oscillatoria.
4. Heterocystous : e.g., Nostoc, Anabaena, etc.
Among these groups only Heterocystous has nitrogen
fixing capacity.

Definition :
Cyanobacteria are defined 'as gram (-)ve prokaryotes
which perform oxygenic photosynthesis and which
possess chlorophyll-a; -carotene; xanthophylllutein,
myxoxanthin, oscillaxanthin, C-phycocyanin, Cphycoerythrin and allophycocyanin; reserve food as
cyanophycean starch, lipid and protein granules but
these lack flagellate cells.

Ultrastructure :
Electron microscope reveals the presence of following
structures in a typical cyanobacterial cell.

Habitat:
Found in fresh, marine and brackish water; on snow,
ice bark, soil and rock surfaces and in hot water
springs and water pipes as a symbionts in many
eukaryotes.
Shape :
Cyanobacteria may be unicellular, colonial or fila mentous. Unicellular forms have single celled body
e.g., synechococcus, chroococcus and Anacystis.
The colonial forms are of two types :

(A) Cell Wall

(a) Dendroid: They are the forms of cyanobacteria in

which cells held together by gelatinous connections
e.g., Chamaesiphon.

The cell wall is four layered with peptidoglycan

present in the second layer.
(B) Cell Membrane

(b) Coccoid: They are unicellular cyanobacterians

embedded in common matrix of mucilage without
gelatinous connections, e.g., Microcystis. Filamentous
forms are thread like multicellular strands in which
each filament or strand consists of a sheath of
mucilage and one or more cellular strands called
trichomes. Spirulina has a spirally coiled filament
while a branched filament is found in Hapalosiphon.
Filaments which have single trichome are divided into
two types :

Semicircular group of coiled infolding often attaches

the cell membrane with the nucleoid.
(C) Cytoplasm
Cytoplasmic streaming is absent and it has following
structures ;
(a) Thylakoids : The thylakoids having PS-I and PSII lie freely in the cytoplasm and have photosynthetic
lemellae which contain photosynthetic pigments.
(b) DNA : Naked and coiled DNA lies generally in
the central part of the cytoplasm known as
centroplasm. It looks like a single chromosome of

(a) Homocystous: They have undifferentiated

trichome e.g., Oscillatoria, Arthrospira.

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Page 10

higher organisms and often called as nucleoid. Some

circular DNA segments also occur in addition to
nucleoid which are known as plasmids or
transposons.

occur by conjugation, transformation and transduction.

Genetic recombination has been reported by H.D.
Kumar in Cylindrospermum and by Khyen in Anacystis
and Anabaena

(c) Ribosomes : 70s ribosomes are found.

Economic Importance:

(d) Carboxysome : It is a structure which is

surroun ded by the nuclear material in the centre of
the cell and it contains enzymes for the dark reaction
of photosynthesis.

I. Useful activities :

(e) Vacuoles : Instead of true vacuoles sap

vacuoles, gas vacuoles or pseudovacuoles are found.
Each gas vacuole consists of a number of sub
microscopic units called gas vesicles which function
as light screen provide buoyancy regulating
mechanism and pneumatic strength.
(f) Cell Inclusions : 4 types of inclusions :
-granules (cyanophycean starch), -granules (lipid
droplets), volutin granules and polyhedral bodies
(ribulose biphosphatecarboxylase) are found. Light
microscope reveals the presence of a central colourless
centroplasm and a peripheral coloured chromo -plasm.

(1) Nitrogen fixation is done by about 50 species of

cyanobacteria. On the basis of nitrogen fixation they
are of two types
(a) Free living nitrogen fixing cyanobacteria:
e.g. , Anabaena, Nostoc, Aulosira, Scytonema,
Stigonema, Gleotrichia, Calothrix, Tolypothrix, etc.
They can fix approximately 15-48 kg nitrogen per
hectare per season.
Aulosira fertilissima is the most active nitrogen fixer
Rice fields. Anabaena also increases the production
Rice. Cylindrospermum is an active nitrogen fixer
Sugar cane and Maize fields. Tolypothrix is used
nitrogen fixer in experimental fields.

in
of
of
as

(b) Symbiotic nitrogen fixing cyanobacteria:

Anabaena and Nostoc species are common symbiont in
lichens, Anthoceros, Azolla and Cycas roots in which it
can fix - nitrogen. Azolla pinnata has Anabaena azollae
in its fronds which is often inoculated to Rice fields for
nitrogen fixation.
(2) They provide food for fish and other aquatic animals
but spirulina is regularly collected for human
consumption in parts of Africa and India (from Samber
lake of Rajasthan). Nostoc in China, Anabaena in India.
(3) They provide suitable conditions for the growth of
other organisms in the hostile environment.
(4) They are used as biofertilizers.
(5) Anabaena and Aulosira do not allow mosquito
Fig. Cyanophyceae. Distribution of akinetes. A.
Gloeotrichia, akinete next to a basal heterocyst; B.
Anabaena desikacharyiensis, series of akinetes next
to an intercalary heterocyst. Note also two terminal
heterocysts; C. Anabaena desikacharyiensis, an
akinete away from the heterocyst.

larvae to grow.
(6) They improve physical texture of soil.

Nutrition :
Cyanophyceae in general are obligate photo autotrophs.
Reproduction :
Cyanobacteria mostly multiply by asexual methods.
Asexual reproduction takes place by means of akinetes,
endospores,
exospores
or
nannocytes.
Sexual
reproduction is absent but gene recombination can

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Heterocyst and Nitrogenase

Points to Remember

Heterocysts are thick walled specialized cells,

larger in size having double wall layers and
terminal depressions with pores called polar
nodules which contain enzyme nitmgenase
reductase and are the sites of N 2 fixation and
reproduction,

Nostoc sp. occur within the thalli of Blasia and

Anthoceros (The Bryophytes).
Nostoc sp. live within the cells of Geosiphon
pyreforme (a fungus) ,
Nostoc sp. occur
(an angiosperm).

in

the

petiole

of

Gunnera

Calothrix sp. live within the cells of Enteromorpha

(a green alga).
Trifolium alexandrinum (Clover) contains Nostoc in its
nodules.
Reddish colour of Red Sea is due to a cyanobacterium
Trichodesmium erythraeum.
Nitrogenase is an oxygen sensitive enzyme made
up of two unequal subunits. The larger subunit
contains C, H, O, N, S. Fe and Mo whereas
smaller subunit contains C, H, O, N, S and Fe
only. Larger subunit has the molecular weight of
1,00,000 3,00,000 while smaller one has the
molecular weight of 50,000 - 70,000.
Molybdenum (Mo) works as an electron acceptor
and donor when nitrogen is reduced to ammonia.

Cyanelle : Cyanobacteria associated with protista.

II. Harmful activities :

Brief account of some important genus :

(1) Microcystis secretes hydroxylamine which kills

aquatic life, birds and cattle while Anabaena cause
gastric
trouble
in
domesticated
animals
by
contaminating the drinking water of these animals.

(A) Gloeocapsa:

(2) Microcystis aeruginosa (= Anacystis cyanea)

Anabaena flos-aquae and Aphanizomenon flos-aquae
not only spoil the taste of drinking water but also toxic
to human beings.

Death factors VFDF (very fast), FDF (fast) and SDF

(slow) are toxins produced by cyanobacteria.
Biological nitrogen fixation has been discovered by
Winogradsky.
Cyanobacteria can fix 10 times as much nitrogen as the
other free living bacteria can fix under suitable
conditions.

OrderNostocales and familyChroococcaceae.

They represents a simple primitive form of unicellular
blue-green algae which are found on wet rocks, wet
ground, pools of water and in laboratory aquaria in
which they forms small masses of jelly and slime.
They reproduce vegetatively by the process of cell
division.

(3) They cause depletion of O 2 supply to aquatic

animals by the formation of bloom by Microcystis,
Anabaena and Nostoc.
(4) Anacystis causes corrosion of metallic water pipe.
The growth of algae is controlled by using algicides
such as dichlorophen, phygon XI, exalgae, cuson etc.

(B) Oscillatoria :
Order-Nostocales and family OsciIlatoriaceae.
It is a filamentous alga found in ditches, shallow
pools of water, sewers and on wet rocks and walls.
It is autotrophic in which reserve food is cyano phycean starch and cyanophycin.
The filaments show oscillation, gliding and bending
movements.
It reproduces vegetatively by fragmentation and
hormogonia formation. No spore formation and no
sexual reproduction has been reported.

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(C) Nostoc :
Order-Nostocales and familyNostocaceae.
It is a colonial alga found in ponds, ditches and other
pools of water, as well as in damp soil in the form of
small masses of jelly.
It also grows in Paddy fields and alkaline soils.
The species N. punctiforme grows as endophyte in
the coralloid roots of cycas and rarely grows as
endophyte in the root nodules of Trifolium.
N. commune grows as a cryophyte in antarctica.
It reproduces vegetatively by fragmentation, hormo gonia formation, akinete formation as well as by
germination of heterocysts.
Mycoplasma

Mycoplasma are unicellular prokaryotic organisms.

They are smalller than viruses (diameter 300 nm to
0.2 nm). Infact Mycoplasma laidlawii has been listed
as the smallest of all the free living organisms with a

has a typical trilamellar unit membrane structure.

Absence of cell wall makes these organisms highly
plastic. Therefore, these can assume various shapes such
as spherical, granular, filamentous, coccoid etc. In
laboratory culture medium colonies of mycoplasma
shows a characteristic fried egg like appearance with an
opaque central area and translucent peripheral zone.
Cells are usually non-motile, but a few forms show
gliding
movement.
Cell
membrane
encloses
protoplasmic matrix which contains ribosomes, fatty
substances and proteins. Proteins represent as many as
40 enzymes which are concerned with the metabolic
activities of the cell. Protoplasm of mycoplasma has
both RNA and DNA. RNA is single stranded and occurs
both in the ribosomes and cytoplasm. DNA is long
coiled double stranded thread that extends almost
throughout the cell. The amount of RNA and DNA in
these organisms is less than half that is usually present
in other prokaryotes. In some species (e.g., M.
gallisepticum) polar bodies, called bleb, protrude one or
the other end of the cell. These are considered to be the
sites of enzymatic activities and attachment during
infection.

diameter of 0.1 to 0.3 m). They do not have a cell

Sensitivity of Mycoplasma :

Mycoplasmas are the smallest known prokaryotic

organisms characterised by absence of cell wall. These
organisms were discovered in 1843 by Pasteur, in the
pleural fluid of cattles suffering from pleuro pneumonia like organisms (PPLO). Nocard and Roux
(1898) were the first to culture these organisms in
artificial medium. Nowak (1929) placed them in the
genus Mycoplasma. Mycoplasma are now known to
infect a large numbers of animals (e.g., dog, sheep,
mice and even man) and plants (e.g., potato, corn,
brinjal etc.). In nature they occur in soil sewage water
and in plant and animal bodies. Besides, they have
also been found in hot water springs. In the
laboratory, they are common contaminants of cultures
rich in organic matter.
Structure :

wall. The outermost limiting layer of the protoplast is

a cell membrane which

Mycoplasma are gram negative. They are insensitive to

penicillin but sensitive to other antibiotics like
erythromycin, chloramphenicol, streptomycin etc. Their
insensitivity to penicillin (and also other antibiotics of
the same class) is perhaps due to absence of cell wall.
This antibiotic interferes in the synthesis of
peptidoglycan, an important constituent of the bacterial
cell wall.
Reproduction :
As far as reproduction in mycoplasma is concerned not
much known about it. However four types of cellular

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Economic Importance :

bodies of Mycoplasma laidlawii have been found.

These are

Mycoplasma are always harmful and causes following

diseases in plants and animals.

(i) Elementary bodies

I. Plant diseases: Many plant diseases caused by

mycoplasma were earlier considered to be viral diseases
before 1967. Since 1967 most of the plant diseases of
yellow group have been reported to be caused by
mycoplasma. Some important mycoplasma diseases
occurring in our country have been reported from
Indian Agricultural Research Institute, New Delhi.
These diseases are

(ii) Secondary bodies

(iii) Tertiary cell bodies and
(iv) Quaternary bodies

Little leaf of brinjal

Citrus greening
Sandal spike
Grassy shoot of sugarcane
Rice yellow dwarf
Cotton little leaf or cotton stenosis
Sesamum phyllody and several others like
Bunchy top of papaya
Fig. Mycoplasma. Binary tission in
Mycoplasma gallisepticum
Elementary bodies reproduce by a process like
budding. These grow in size and then again give rise
to elementary bodies. In some cases binary fission
also occurs.
Points to Remember
Mycoplasma are also known as Joker of plant
kingdom, mollicutes or PPLOs.
Archebacteria are the simplest and ancient.
Halophiles live in strong brine or salt solution. In
strong light, they develop purple pigments in their cell
membrane which can absorb solar radiations to carry
out their metabolic activities by producing ATP.
Nature of Mycoplasmas :
Mycoplasma can pass through bacteriological filters
and do not possess a typical bacterial cell wall. These
two characters confirm that mycoplasmas are not
bacteria. As these micro-organisms can multiply in
medium which does not contain living tissue, hence,
they are not viruses either (viruses show characters of
life only inside the living host). These characters,
therefore, show that mycoplasmas are intermediate
between bacteria and viruses.

Aster yellows
Potato witche's broom
11. Animal diseases: Diseases like rheumatism,
arthritis, several respiratory disorders and primary
atypical pneumonia (PAP) are caused by mycoplasma.
Mycoplasma hominis and M. fermentans etc. are
supposed to cause infertility in human males.
The Rickettsiales
The Rickettsiales or the Rickettsia type organism or
rickettsial organisms are the organisms which bear a
morphologic affinities are highly disputable. They are
so named in honour of Howard Taylor Ricketts who
first described these organisms in course of h is studies
on Rocky mountain spotted fever and subsequently on
typhus fever. Ricketts observations were later confirmed
by da Rocha-Lima in 1916. After Ricketts, these
organisms were reported by Hegler, Prowa Zek and
others in the blood of patient sufferin g from typhus
fever.
Size:
The individual organisms are about at the lower size
limit for bacteria and about at the upper limit for
viruses, commonly measures about 0-3 n in diameter
and 2 or less in length.
Shape:
They are rod shaped, coccoid or irregularly shaped
non-motile micro-organisms.

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Structure :
Observations with the electron microscope show that
they have a definite cell wall surrounded by capsular
material, just as in bacteria. They contain both RNA
and DNA. They are stained readily by giemsa's
stain. The wall material is composed of muco
complex substance.
The rickettsial organisms reproduce by binary fission
similar to bacteria and may be seen in light
microscope.
Rickettsia and Disease:
Some human pathogenic effect of Rickettsia has been
tabulated in following table
S.N.

Name of Disease

Causative agent

1.

Rocky mountain
spotted fever (Tick)

Rickettsia-rickettsiae

2.

Typhus fever (Lice)

Rickettsia
prowazekii

3.
4.
5.
6.

Murine typhus (Flea)

Scrub typus (Mite)

R. typhi

These micro-organisms link bacteria with the fungi.

Like the fungi their somatic structure consists of
multicellular threads (hyphae) which collectively form
the mycelium. They produce asexual spore also known
as conidia on aerial hyphae which act as asexual spores
of fungi and unlike endospores of bacteria. They are
heat killed and hot heat resistant. Their spores and cells
never cover more than 2 or 3 microns () in diameter.
The actinomycetes are saprophytes or parasites. Some
of them successfully live in soil (e.g., streptomyces
spp.). On the other hand some are found only in semi aquatic habitats (e.g., micromonospora spp.) provided
by Lacatrine muds. Some members (e.g., Nocardia spp.)
are known to decompose substrate like paraffin, phenol,
petroleum derived materials which are so resistant that
they are untouched by the majority of bacteria. Forms
like (Actinomycetes spp.) are specialized parasites and
found in the mouth of mammals.

R. tsugamuschi

Rickettsial pox (Mite)

Tick
borne
(Tick)

R. akari
fevers R. conorii

The above mentioned rickettsial organism are found

typically in arthropod. They may cause diseases in
man and other animals. In the arthropod host most
rickettsias do not produce symptoms of disease but
they are transmitted by arthopod bite other animal host
such as man.
Classification :
The Rickettsiales are sub divided into following three
families
Family Rickettsiaceae: These are rod shaped to
coccoid bacterium like organisms that are intimately
associated with arthopod tissues. They may be
parasitic to man and other animals causing typhus and
Q fever.

Fig. Life cycle of an actinomycete

In Actinomycetes the reproduction takes place by
means of fragmentation of the hyphae, by conidia
produced singly or in chains. In certain actinomycetes
the reproduction takes place by minute sporangia
producing motile or non-motile spores.

Family Bartonellaceae: These are rod shaped,

coccoid, ring shaped, filamentous to beaded organism
and are parasites of the erythrocytes in man, cause
haemobartonellosis,
grahamellosis
and
erythrozoonosis in lower animals.

Economic Importance:
The genus streptomyces of this group is most
important, some species of which produce antibiotic
substance of great medicinal value like streptomycin,
chlorotetracycline, oxytetracycline, tetracycline,
chlo-ramphenicol and erythromycin.

Family Chlamydozoaceae: These are coccoid

organisms which behave as obligate intracytoplasmic
parasites.
Actinomycetes (RayFungi)

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Archaebacteria

Page 15

Introduction:
Archaea are tiny, usually less than one micron long
(one one-thousandth of a millimeter). Even under a
high-power light microscope, the largest archaeans
look like tiny dots. You might think that organisms so
small would not have much variety of shape or form,
but in fact archaeal shapes are quite diverse. Some are
spherical, a form known as coccus, and these may be
perfectly round or lobed and lumpy. Some are rod shaped, a form known as bacillus, and range from
short bar-shaped rods to long slender hair-like forms.
These are ancient and primitive bacteria. Commonly
called as extremophiles.
Basic Archaeal Shapes : Methanococcus janaschii,
a coccus form with numerous flagella attached to one
side. Methanosarcina barkeri, a lobed coccus form
lacking flagella. Methanothermus fervidus, a short
bacillus form without flagella. Methanobacterium
thermoautotrophicum, an elongate bacillus form.
Structural diversity among archaeans is not limited to
the overall shape of the cell. Archaea may have one or
more flagella attached to them, or may lack flagella
altogether. The flagella are hair-like appendages used
for moving around, and are attached directly into the
outer membrane of the cell. When multiple flagella are
present, they are usually attached all on one side of the
cell. Other appendages include protein networks to
which the cells may anchor themselves in large groups.
Like bacteria, archaeans have no internal membranes
and their DNA exists as a single loop called a plasmid.
However, their tRNAs have a number of features that
differ from all other living things. The tRNA
molecules (short for "transfer RNA") are important in
decoding the message of DNA and in building
proteins. Certain features of tRNA structure are the
same in bacteria, plants, animals, fungi, and all known
living things -- except the Archaea. There are even
features of archaeal tRNA that are more like
eukaryotic than bacteria, meaning that Archaea share
certain features in common with you and not with
bacteria. The same is true of their ribosomes, the giant
processing molecules that assemble proteins for the
cell. While bacterial ribosomes are sensitive to certain
chemical inhibiting agents, archaeal and eukaryotic
ribosomes are not sensitive to those agents. This may
suggest a close relationship between Archaea and
eukaryotes. As with other living things, archaeal cells
have an outer cell membrane that serves as a barrier
between the cell and its environment. Within the
membrane is the cytoplasm, where the living functions
of the archeon take place and where the DNA is
located. Around the outside of nearly all archaeal cells
is a cell wall, a semi-rigid layer that helps the cell
maintain its shape and chemical equilibrium. All three

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of these regions may be distinguished in the cells of

bacteria and most other living things, but when you take
a closer look at each region, you find that the
similarities are merely structural, not chemical. In other
words, Archaea build the same structures as other
organisms, but they build them from different chemical
components. For instance, the cell walls of all bacteria
contain the chemical peptidoglycan. Archaeal cell walls
do not contain this compound, though some species
contain a similar one. Likewise, archaea do not produce
walls of cellulose (as do plants) or chitin (as do fungi).
The cell wall of archaeans is chemically distinct.
Types of Archaebacteria:
Archaeans include
inhabitants of some of the most extreme environments
on the planet. Some live near rift vents in the deep sea
at temperatures well over 100 degrees Centigrade.
Others live in hot springs, in extremely alkaline or acid
waters, or in extremely saline water.
Three types
(1) Halophiles: Example: Halobacterium, lives in
enormous numbers in salt ponds. An interesting fact
about Halobacterium is that the red light-sensitive
pigment that gives Halobacterium its color, which is a
simple photosynthetic system that provides the archaean
with chemical energy, is known as bacteriorhodopsin - and is chemically very similar to the light -detecting
pigment rhodopsin, found in the vertebrate retina.
(2) Methanogens: Methane producing bacteria, found
in marshy and muddy areas. These are anaerobic.
(3) Thermoacidophiles: Grow at high temperature
and acidic pH.
Chlamydia
Introduction:
Chlamydia is caused by the bacterium Chlamydia
trachomatis. The word chlamys is Greek for "cloak
draped around the shoulder." This describes how the
intracytoplasmic inclusions caused by the bacterium are
"draped" around the infected cell's nucleus. Because the
symptoms of the disease resemble other pathologies,
chlamydia was not recognized as a sexually transmitted
disease until recently. Isolation from embryonated eggs
in 1957 and from cell culture in 1963 confirmed its
existence as a bacterium. However, since the organism
is an obligate intracellular parasite that exclusively
infects humans (it cannot synthesize its own ATP or
grow on artificial medium), it was once thought to be a
virus. Because of Chlamydia's unique developmental
cycle, it was taxonomically classified in a separate
order. It can thus be found with the other wel l-known
intracellular parasites, rickettsiae, in diagnostic
manuals. Chlamydia has a genome size of approximately

Page 16

500-1000 kilobases and contains both RNA and DNA.

The organism is also extremely temperature sensitive
and must be refrigerated at 4 C as soon as a sample is
obtained.

4. Bacteria lack alternation of generations because

there is

Objective Problems :

a) Neither syngamy nor reduction division

1. Maximum number of antibiotic got from any group is

a) Actinomycetes

b) Fungi

c) Eubacteria

d) Viruses

b) Distinct chromosomes are absent

c) No conjugation
d) No exchange of genetic material

(ZIPMER 87, AIIMS 97)

(CBSE 91, 92)

2. Streptomycin is produced by

5. In bacteria, sexuality/conjugation was d iscovered by

a) Streptomyces

a) Lederberg and Tatum b) Zinder and Laderberg

b) Strptomyces fradiae

c) Watson and Crick

c) Streptomyces venezuellae
d) Streptomyces griseus

d) Hershey and Chase

(AMU 89, DPMT 97)

(BHU 83, MPPMT 91)

6. Nitrosomonas changes

3. The term antibiotic was first used by

a) Fleming

b) Pasteur

c) Waksman

d) Lister

b) Nitrogen to Ammonia

c) Ammonia to nitrogen

d) Ammonia to nitrite

(BHU 88, CPMT 93, MPPMT95)

(BHU 85, CBSE 94, DPMT 97)

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a) Nitrite to nitrate

Page 17

(AFMC84,CPMT86,BHU85,MPPMT91)

7. Vinegar is produced by

15. Germ theory of disease was put forth by

a) Two step process first fermentation of sugar by

yeast, second fermentation of ethyl alcohol by acetic
acid bacteria

a) De Bary

b) Lister

c) Pasteur

d) Koch

b) Fermentation of sugar by Lactobacillus

(AFMC 90, MPPMT 95)

c) Fermentation of sugar by Aspergillus

d) Fermentation of sugar by saccharomyces cereviviae

16. Bacterial cell wall is composed of

(DPMT 82, MPPMT 92)

a) Lipid
c) Chitin

8. Bacteria that convert nitrates into free nitrogen are

a) Ammonifying

b) Nitrifying

c) Denitrifying

d) Nitrogen fixing bacteria

17. Escherichia coli is used extensively in biological

research as it is

9. A free living anaerobic nitrogen fixing bacterium is

b) Streptococcus

c) Azotobacter

d) Clostridium

d) Mucopeptide/Peptidoglycan
(AMU 92, MPPMT 97, ZIPMER 97)

(ZIPMER83, MPPMT89,92,96,CPMT94)

a) Rhizobium

b) Cellulose

a) Easily cultured

b) Easily available

c) Easy to handle

d) Easily multiplied in host

(MPPMT 93, CBSE 93)

18. Genophore /bacteria genome or nucleoid is made of

(DPMT84, CPMT 84, 85,MPPMT 92, 96)

a) Histones and nonhistones

b) RNA and histones

10. A bacterial disease is

a) Measles

b) Tuberculosis

c) A single double stranded DNA

c) Rabies

d) Small pox

d) A single stranded DNA

(CBSE 93, MPPMT 96)

(MPPMT 89,90, 91, Bih. PMT 90)

19. Plasmid is

11. Botulism is
a) Human disease due to parasitic bacteria

a) Small extrachromosomal circular self replicating

DNA that can carry genes into host organism

b) Disease of various organisms

b) Bacteriophage

c) A type of food poisoning

c) DNA found in mitochondria

d) A viral disease (RPMT 85, MPPMT 91, 92)

d) DNA incorporated in bacteria chromosome

(DPMT87,MPPMT 88,91,92, BHU 83,92, AIIMS
90, CPMT 93, 94,APMEE 96)

12. The main difference in gram(+ve) and Gram

(-ve) bacteria resides in their
a) Cell wall

b) Cell membrane

c) Cytoplasm

d) Flagella

20. Nitrogen fixer soil organisms belongs to

(CBSE 90, Manipal 97)

13. A bacterium with flagella all around is
a) Amphitrichous

b) Lophotrichous

c) Cephalotrichous

d) Peritrichous

a) Mosses

b) Bacteria

c) Green Algae

d) Soil Fungi
(CBSE 94, Pb. PMT 97)

21. Cell wall of bacteria/cyanobacteia possesses

(AFMC 81, AMU 83, MPPMT 90, RPMT 91,

CPMT 92, Har. PMT 93)

a) Chitin

14. Nitrosomonas and nitrobacter convert

b) Cellulose

a) Carbon dioxide to carbohydrates

c) Murein / Mucopeptide

b) Ammonium ion into nitrate

d) Peptidoglycan and amino sugars

c) Nitrate ion into nitrogen molecule

(Har/ PMT 94, AMU 94)

d) Nitrogen into nitrate

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Page 18

22. Cyanobacteria belongs to

30. Rhodospirillum, a photoautotrophic bacteraium is

a) Plantae

b) Protista

a) Facultative aerobe

b) Free living anaerobe

c) Monera

d) Metaphyta

c) Free living aerobe

d) Obligate parasite

(Har. PMT 94, CBSE 96)

(BHU 87, 88)

23. In Whittakers classification, non-nucleated

unicellular organisms/ procaryotes are included under

31. The main function of elementary bodies in

Mycoplasma is

a) Plantae

b) Monera

c) Protista

d) Animalia

a) Reproduction

b) Respiration

c) Secretion

d) Food storage
(MPPMT 95, 98, RPMT 95)

(MPPMT 94, BHU 97)

32. In prokaryotes the ribosomes are

24. Salmonella typophosa (= S. typhi) is the pathogen

of

a) 50S

b) 80S

c) 70S

d) 30S

(DPMT83, BHU85, MPPMT 95, BHU96)

a) Pneumonia

b) Typhoid

c) Influenza

d) Whooping cough

33. Which one is found in alimentary canal of humans?

(BHU 85, 88)

25. Chloramphenicol/chloromycetin is produced by

a) Pseudomonas

b) Rhizobium

c) Bacillus

d) Escherichia coli
(RPMT 95, APMEE 95)

a) Streptomyces rimosus
b) Streptomyces venezuelae

34. The condition of having a single flagellum at one

end of a bacterium is

c) Stretomyces griseus
(BHU 83, 89)

d) Streptomyces scoleus

26. Bacteria lacking flagella and moving by gliding are

a) Pertrichous

b) Amphitrichous

c) Lophotriichous

d) Monotrichous
(AMU 97, Pb. PMT 97)

a) Rickettsiae

b) Eubacteria

c) Spirochaetes

d) Myxobacteria

35. Food poisoning is due to

(MPPMT 92, BHU 92)

a) Clostridium botulinum b) Salmonella typhi

27. A free living as well as symbiotic nitrogen fixing

prokaryote is

c) Escherichia coli

d) Bacillius megatherium

a) Spirogyra

b) Anabaena

36. Which is not correct about antibiotics?

c) Oedogonium

d) Cladophora

a) Fleming discovered the first commercial antibiotic

(AIIMS 96,CET Chd. 97)

(BHU 90, 91)

b) Waksman coined the term antibiotic in 1942.

28. Nuclear material without nuclear envelope occurs in

c) Allergy may develop against an antibiotic

a) Mycoplasma and green algae

d) An antibiotic is effective against one specific

pathogens

b) Bacgtera and green algae

(CBSE 96, CET Chd. 97)

c) Bacteria and cynanobacteria

37. Blue-green alga that causes red blooms is

d) Cyanobacteria and red Algae

(MPPMT94, AMU 98 )
29. Land becomes slippery during rains due to growth of
a) Moss

b) Brown Algae

c) Green Algar

d) Blue-Green Algae

a) Anabaena

b) Gleocapsa

c) Trichodesmium

d) Nostoc
(BHU 96, CET Chd. 97)

38. Which is a procaryote?

(CPMT 94, ZIPMER97)

a) Rhizopus

b) Spirogyra

c) Nostoc

d) Saccharomyces
(AMU 97, Pb. PMT 98)

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Page 19

39. Citrus canker is due to

a) Bacterium

b) Virus

c) Fungus

d) Alga

c) Transduction

d) Transformation

c) Chlamydomonas

d) none of the above

49. Bacteria lack

40. Transfer of DNA fragments from a donar to

receptor bacterial cell through the medium is
b) Transcription

b) mitochondria

(BHU, 75)

(CPMT 96, MPPMT 97)

a) Translation

48. Bacteria resemble

a) Nostoc species

a) endoplasmic reticulum

b) DNA

c) cell wall

d) cytoplasm
(DPMI, 84)

50. What is the general shape of bacteria?

(AIIMS 94, DPMT 94)

41. Unicellular cyanobacteria reproduce asexually by
a) Binary fission

b) Fragmentation

c) Hormogones

d) Conjugation

a) Rod

b) Spheres

c) Spirals

d) Cubes
(CPMT, 75)

51. Bacteria which are smallest in size are

(MPPMT 97, AIIMS 97)

42. Which one is included under prokaryotes?

a) vibrio

b) cocci

c) spirilla

d) bacilli
(AFMC, 74)

a) Mycoplasma
52. Diaminopimelic acid
constituents of cell wall of

b) Alage
c) Ulothrix
d) Mycoplasma and Blue green Algae

and

muramic acid are

a) higher plants

b) fungi

c) bacteria

d) bacteriophage

(RPMT 95, 96)

(MPPMT, 87)

43. Antony von Leeuwenhoek, the first to discover

bacteria is from

53. Bacteria have the following organelle

a) mesosomes

b) Golgi bodies

a) U. K.

b) Sweden

c) mitochondria

d) chloroplasts

c) France

d) Holland

(CPMT, 84; DPMT, 85)

(CPMT, 84)

44. Germ Theory of Disease' was given by

54. An organism which is generally without plastids

and can synthesize its organic food is

a) Robert Koch

b) Louis Pasteur

a) bacteria

b) viruses

c) A. V. Leeuwenhoek

d) None

c) fungi

d) bacteriophage
(CPMT, 84)

(BHU, 82)
45. Pure cultures of bacteria were first obtained by

55. Nucleoids are found in all

a) R. Koch

b) L. Pasteur

a) plant cells

c) A. Leeuwenhoek

d) J. Lister

b) bacterial cells
(BHU, 84)

c) bacterial cells blue green algae

46. Bacteria are considered to be plants because they

a) have rigid cell wall

d) plant cells, bacterial cells, blue green algae

b) can not move

(MP PMT, 86)

c) are present everywhere d) can multiply by fission

56. The structure formed by bacterial genome is

generally called

(CPMT, 84)
47. The cells of cyanobacteria and bacteria exhibit
similarity in having similar
a) plastids

b) nuclei

c) centrosome

d) DNA

b) nucleoside

c) nucleolus

d) nucleoid
(BHU, 84, R PMT, 85)

57. Plasmids are

(BHU, 82)

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a) nucleus

a) viruses

Page 20

b) new types of micro-organisms

65. A free living anaerobic bacterium capable of fixing

nitrogen is

c) extra chromosomal genetic elements of b acteria

d) essential bacterial genetic elements
(BHU, 84)

a) Azotobacter

b) Rhizobium

c) Clostridium

d) Streptococcus
(D PMT, 83; CPMT, 84, 85)

58. Circular DNA is seen in

a) blue green algae
c) fungus

66. Milk spoilage is due to

b) bacteria
d) viruses

a) Aspergillus

b) Pseudomonas

59. The hydrogen donor in bacterial photosynthesis is

usually
a) water
b) hydrogen sulphide

c) LactobaciUus

d) Staphylococcus

c) sulphuric acid

67. Wine turns sour because of

a) heat
b) aerobic bacteria

(CPMT, 77)

d) NH 4
(BHU, 82)

60. Which one of the

carbohydrates ?

following

fixes

CO 2

c) anaerobic bacteria

into

d) exposure to heat
(CPMT, 74)

a) Rhizobium

b) Nitrobacter

c) Bacillus

d) Rhodospirillum

68.Vinegar is produced
a) by fermentation of sugar by Lactobacillus
(BHU, 79)

b) by fermentation of sugar by Aspergillus

61. Chemosynthetic bacteria are those bacteria which

c) by fermentation
cerevisiae

a) do not carry out photosynthesis

b) synthesize food without light

of

sugar

by

Saccharomyces

d) is a two step process, first involving fermentation of

sugar by yeast and second involving fermentation of
ethyl alcohol by acetic acid bacteria.

c) are unable to carry out chemical reactions

d) carry out synthesis in light

(D PMT, 82)

(D PMT, 81)

69. A bacterium whicn is commonly present in the

intestine of man and animals is
a) Bacillus brevis
b) Escherichia coli

62. Some bacteria are not easily killed because of

a) their tolerant power

b) chitinous wall

c) capsule

d) endospore formation

c) Streptococcus lacti

d) Pseudomonas citri

(MP PMT, 86)

(CPMT, 86)

63. The process in which viruses are involved (genetic

material is carried by some external agency) in sexual
reproduction of bacteria is called

70.A compound which is produced by an organism and

inhibits the growth of another organism is called

a) transduction

b) conjugation

a) antiseptic

b) anticoagulant

d) translation

c) antibiotic

d) antiallergic

c) transformation

(BHU, 81; AFMC, 82)

(BHU, 80)

64. Which of the following is not true for Escherichia

coli ?
a)
Gene
recombination
can
occur
transformation, transduction and conjugation.

71.Antibiotics are mostly obtained from

through

a) bacteria

b) viruses

c) angiosperms

d) fungi

b) It occurs in human intestine

(CPMT, 79)

c) It has no true nucleus

72. Broad spectrum antibiotic is one which

d) It is diploid

a) acts on all bacteria and viruses

(DPMT, 82)

b) acts on variety of pathogenic micro -organisms

c) is effective in very small amounts
d) acts on both pathogens and host

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Page 21

(D PMT, 86)

d) low temperature causes plasmolysis

73. Chloromycetin (or chloramphenicol) is derived
from

(CPMT, 71,84)
81. Clear areas of agar plates containing phage
particles as well as bacteria are called
a) bacteriophage
b) transparencies

a) Streptomyces venezuelae b) Streptomyces griesus

c) Streptomyces scoleus

d) Streptomyces ramosus

c) plaques

(BHU, 85)

82. The visible appearance of growths of bacteria seen

on laboratory culture media are called

74. Wakesman was awarded Nobel prize for the

discovery of
a) penicillin
b) Chloromycetin
c) streptomycin

d) neomycin

d) holes

(BHU, 71)

a) a thallus

b) spores

c) colonies

d) tissues

75. Botulism is a

(CPMT, 75)

a) type of food poisoning caused by saprophytic

Clostridium

83.The main difference between gram positive and

gram negative bacteria resides in the composition o f

b) disease caused by Staphylococcus in man

a) cilia

b) cell wall

c) disease of Citrus

c) nucleolus

d) cytoplasm

d) water borne disease of animals

(R PMT,85)

(CBSE, 90)

76. Some diseases caused by bacteria are

84. Bacterium whose cells has only a single curve is

known as

a) measles, mumps, malaria

a) vibrio

b) tetanus, typhoid, tuberculosis

c) sprillum

b) cocci
d) bacillus

c) small pox, sleeping sickness, syphilis

(CPMT, 90)

d) pneumonia, poliomyelitis, psitacosis

85. Bacteria do not have

(CPMT, 87)

77. Bacterial leaf blight is a serious disease of

a) paddy

b) wheat

c) potato

d) tomato

b) cell wall

c) plasma membrane

d) ribosomes
(CPMT, 92)

86. Bacteria do not have a major role in the production

of following

(BHU,87)
78. Equipment
for
sterilizing
other laboratory equipments is

a) mitochondria

glassware

a) incubator

b) autoclave

c) oven

d) dehumidifier

and

a) coffee

b)B-complex

c) cheese

d) bread

87. Episome or F factor is extra chromosomal genetic

material of bacteria, useful in

(BHU, 82; D PMT 84)

a) control of essential characters

79. When milk is heated at 62C for 30 minutes and

then cooled, the process is called

b) genetic recombination.

a) sterilization

b) pasteurization

c) formation of endospores

c) nitrification

d) freezing

d) nitrogen fixation
(PMT, 85)

88. Many bacteria bear minute hariy structures on their

cell wall, these are called

80. We can keep food for longer duration in cold

storage than in ordinary cupboard because

a) hairs
c) piti

a) insects can not cause infection

(AFMC. 96)

b) bacterial multiplication is completely prevented

c) bacterial mulitplication is greatly reduced

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b) flagella
d) cilia

Page 22

89. Azotobacter and Bacillus palymyxa are examples of

c) double - stranded and linear

a) symbiotic N 2 fixer

b) non-symbiotic N 2 fixer

d) double - stranded and circular

d) pathogenic bacteria

c) decomposers

(CBSE, 98)
99. The main role of bacteria in the carbon cycle
involves

(CBSE, 96)
90. Which type of DNA is found in bacteria?
a) Straight DNA

a) assimilation of nitrogenous compound

b) Helical DNA

b) photosynthesis

c) Membrane bound DNA d) Circular DNA

c) chemosynthesis

(CBSE, 96)

d) digestion or breakdown of organic compounds

91. Bacteria resemble

a) Nostoc

b) mitochondria

c) Chlamydomonas

d) none

(CBSE, 98)
100. Transfer of genetic information from one
bacterium to another in the transduction process is
through

92. Hydrogen donor in bacterial photosynthesis is

usually
a) water
b) hydrogen sulphide
c) sulphurous acid

a) physical
strains

d) ammonia

d) less carbohydrates

b) Clostridium

c) Mycobacterium

c) Vibrio choleras

d) another bacterium

95. All living organisms are killed by heat treatment,

known as
a) pasteurization
b) immunity

a) Cell wall

b) Cell membrane

c) Slime layer

d) Capsule

2. Mycoplasma is the causative agent for one of the

following diseases

d) dehydration
(AFMC, 96)

96. Food poisoning is caused by

a) Vein yellowing

b) Leaf curl

c) Aster yellow

d) Tobacco mosaic

3. Nocard and Roux are known for the discovery of

a) Clostridium botulinum b) Micrococcus

d) Lactobacillus
(CPMT, 98)

a) PPLO

b) Cyanophage

c) TMV

d) Bacteriophage

4. Pleura-pneumonia
under

97. Botulism caused by Clostridium botulinum affects

the
b) intestine

c) neuromuscular junction d) spleen

like

organisms

a) Prokaryotes

b) Eukaryotes

c) Fungi

d) Viruses

are

grouped

5. Mycoplasma are not viruses in nature because

(CBSE, 98)

a) These contain both DNA and RNA in the same cell

98. The DNA of E. coli is

b) These can be grow artificially in cultures also

a) single - stranded and circular

c) The outermost layer is not made of proteins only

b) single - stranded and linear

d) All of the above

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(CBSE, 98)

1. The outermost limiting layer of typical cell of

mycoplasma is a

(AFMC, 96)

a) lymph glands

recipient

Toward Perfection:

a) Pasteurella pestis

c) Mycobacterium

donor and

c) bacteriophages released from the doner bacterial

strains

94. Plague is a bacterial disease caused by

c) sterilization

between

b) conjugation

93. The cell wall of gram negative bacteria has

a) more lipids
b) less lipids
c) more carbohydrates

contact

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6.

Cyanobacteria are

a) Photoautotrophs

b) Photoheterotrophs

c) Chemoautotrophs

d) Chemoheterotrophs

15. The type of DNA and RNA found in the cell of

mycoplasma are respectively
a) 2 stranded and 1 stranded
b) 1 stranded and 2 stranded

7.Cells in some filamentous cyano- bacteria that are

specialized for nitrogen fixation are called

c) Both one stranded

a) Phycobilisomes

b) Chromatophores

d) Both two stranded

c) Grana

d) Heterocysts

16. Water bloom is generally caused by-

8. The bacteria (Treponema palli-dium) that cause the

veneral disease syphilis are
a) Pseudomonas

b) Purple non-sulphur

b) Rickettsias

d) Spirochetes

a) Green algae

b) Blue greenalgae.

c) Bacteria

d) Hydrilla

17. Nostoc occurs as endophyte in

a) Anthoceros

b) Azolla

9. The bacteria that cause Leprosy and Tuberculosis

both are the

c) Cycas

a) Archebacteria

b) Actinomycetes

18. Indian authority

cyanophycean members

on

c) Eubacteria

d) Mycoplasma

a) M.O.P. lyenger

b) R.N.Singh

c) H.D. Kumar

d) D.C. Pandey

10. Little leaf of brinjal is caused by

d) All of the above

nitrogen

fixation

by

a) Fungi

b) Virus

19. Cyanophycean forms which live endophytically in

protozoans are called ?

c) Bacteria

d) Mycoplasma

a) Cyanophages

b) Bacteriophages

c) Cyanelle

d) Plasmids

11. Cyanobacteria are called 'myxo-phyceae' because

they are

20. The bioferilizers are

a) Encapsulated by a gelatinous sheath

a) Cow dung, manure and farmyard waste

b) All nitrogen fixers

b) Quick growing crop ploughed under soil

c) Mesokaryotic in nature

c) Anabaena and Azolla

d) Filamentous bearing heterocysts

d) None of these

12. Nitrogen fixing organism in the nodules of

Trifoliom alexandrium is a) Aulosira
c) Oscillatoria

21. In Cyanobacteria the nucleus is surrounded by

a) Single layered membrane

b) Lyngbya

b) Double layered membrane

d) Nostoc

c) No membrane

13. Cyanobacteria which can tolerate the freezing

temperature is
a) Phormidium

b) Oscillatoria

c) Trichodesmium

d) Gleocapsa

d) None of these
22. The storage products
(Cyanobacteria) are-

blue

green

algae

a) Manitol

14. Marbind cells are (Nekridia) are

b) Cyanophycean starch and proteins

a) Dead cells

c) Algin

b) Helpful in breaking of filament into segments called

hormogonia

d) Agar- gar

23. Which of the following groups of Cyanobacteria

has mostly immotile members ?

c) Found in filaments of cyanobacteria

a) Pseudocapsalean

d) All of the above

c) Chroococcacean

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in

Page 24

b) Heterocystous
d) Oscillatorian

24. Typhus disease in human being is caused by

c) adeno virus

d) none of the above

a) Mycoplasma

b) Rickettsiales

35. In Influenza virus the nucleic acid core consists of a

c) Actinomycetes

d) All of the above

a) single stranded RNA

b) single stranded DNA

25. Antibiotic chloramphenicol can be obtained by

c) double stranded RNA

d) double stranded DNA

a) Fungi

b) Bacteria

36. A virus having a tadpole like structure is

c) Mycoplasma

d) Actinomycetes

a) TMV

b) T 4 bacteriophage

26. Q. fever is caused by

c) adeno virus

d) all of the above

a) Actinomycetes spp

b) Mycoplasma gallisepticum

37. virion refres to-

c) Coxiella burnetti

d) None of these

a) entire virus unit

b) capsid

c) bacteriophage

d) helical virus

27. Function of elementary bodies in mycoplasma is

38. Capsid is made up of-

a) Respiration

b) Assimilation

a) lipoproteins

b) proteins

c) Excretion

d) Reproduction

c) proteins and sugars

d) proteins and RNA

28. Rickettsiae is a group of

39. An example of DNA RNA viruses is-

a) Viruses

b) Bacteria

a) leukoviruses

b) pox viruses

c) Microorganisms

d) PPLO

c) linfluenza virus

d) all of the above

29. A mixture of bacteria, viruses and mycoplasma is

strained through a filter with 450 nm pore size.
Which of these would not pass through ?
a) Bacteria

b) Mycoplasma

c) Virus

d) All of these

40. Viruses cousing poliomyelitis and rabies area) neurotropic

b) dermotropic

c) pneumotropic

d) visocerotropic

41. Viruses cousing measles are-

30. Product of Photosynthesis in blue green algae

generally is

a) Neurotropic

b) dermotropic

c) pneumotropic

d) pneumotropic

a) Glucoside

b) Glycogen like

42. Which is not a viral disease?

c) Glycerophosphate

d) Globulin

a) typhoid

b) measles

31. All viruses are-

c) poliomyelitis

d) rabies

a) Obligatory intercellular parasites

43. When juice from tobacco plants infected with

mosaic disease was injected into healthy plants, it
reproduced the disease. This was first demonstrated by:

b) Obligatory intracellular parasites

c) Facultative intercellular parasites
d) Facultative intracellular parasites
32. Poliovirus is a . Virus.

a) Ivanovski

b) Mayer

c) Stanley

d) d, Herelle

a) naked capsid

b) enveloped capsid

44. A bacteriophage consists of only protein and DNA.

This was first shown by-

c) helical symmetry (TMV)

d) tadpole like

a) Koch

b) Chase

33. Bacteriophages were discovered by-

c) Mayer

d) Schelsinger

a) Stanley

b) Ivanovski

45. Infection of T 4 bacterioophage is-

c) Heshey

d) d Herelle & Twort

a) virulent

b) temperate

c) may be a or b

d) neither a nor b

34. A virus found in the colon of man isa) Escherochia coli

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b) TMV

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46. Hershey and Chase showed that-

a) Infection

a) penetration of viral DNA into host cells causes

infection

b) Lysis

b) virus can be crystallized

d) Positive Negative interaction

c) Adsorption

c) viruses cause several disease

56. Viruses were discovered by

d) viruses consist of nucleoproteins

47. In Iysogenic, the mode of infection isa) Virulent

b) temperate

c) intermediate

d) all of the above

a) Stanley

b) Ivanowsky

c) Conrat

d) Sinsheimer

57. Bacteriophages were discovered and named by

48. Viruses are supposed to be a link between

a) Conrat

b) Ivanowsky

c) Sinsheimer

d) d Herelle

58. T.M.V. was frist isolated and crystallized by

a) bacteria and blue green algae

b) bacteria and protozoa
c) inanimate and animate objects

a) Stanley

b) Ivanowsky

c) d Herelle

d) Conrat

59. The fact that during virus infection only nucleic

acid takes part was established by

d) plants and animals

49. When the viral chromosomes becomes a part of host
chromosome, it is called as :

a) Stanley

b) Conrat

c) Watson

d) Vilkins

a) virion

b) provirus

60. Single stranded DNA is present in

c) lytic virus

d) none

a) Polimeelitis virus

b) Bacteriophage

c) phi X 174

d) TMV

50. When the viral chromosome becomes a part of a

bacterial chromosome, it is called
a) prochromosome

b) pro-DNA

c) provirus

d) prophage

61. The classification of virus was proposed by

51. The plasmid of maleness is called

a) Stanley and Miller

b) Jacob and Monad

c) Zinder and Lederberg

d) Lwoff and Tourner

a) R-Factor

b) R.T.F.

62. Because viruses multiply only in the living cells,

they are called as

c) K-12

d) F-Factor

a) obligate inter cellular parasites

b) obligate aerobes

52. Such cells which are able to transfer chromosomal

genes to recipient cells with high frequency are called

c) obligate intra cellular parasites

a) K-12 cells

b) HF cells

d) obligate anaerobes

c) HR cells

d) HFR cells

63. The living properties of viruses are that, they can

53. Transfer of host genes though F Factor during

conjugation is called

a) be crystallized

b) respire

c) mutate and adapt

d) manufacture food

a) Trasduction

b)Transformation

64. Viruses are

c) Sexduction

d) Cojugation

a) cellular organisms

b) Acellular organisms

c) unicellular organisms

d) cellular without wall

54. R Factor refers to

a) RTF

b) r-determinants

65. A technical term used for virus is

c) RTF + r determinants

d) none of these

a) capsid

b) nucleiod

c) virion

d) nucleoprotein

55. For attachment of phage with bacterial cell the first

step is

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66. The sub-units of protein coat of viruses are called

as
c) chromomeres

b) capsomeres

c) capsid

d) lipoproteins

a) Prophage

b) Vegephage

c) Cyanophage

d) Phycophage

77. One of the interesting features of viruses is that

they

67. The viruses which are bacteria eaters are called as

a) multiply only in the host cytoplasm

a) cyanophages

b) Algophages

a) are made of proteins only

c) phycophages

d) phages

c) behave as if they were plants

68. The smallest virus is

d) occur only inside bacteria

a) Foot and mouth virus of cattle

b) Tobacco Mosiac virus

78. Viruses with types of symmetry viz. icosahedral

head and helical tail are known as

c) Coliphage lambda virus

a) Picorna viruses

b) Binal viuses

d) Wound tumour virus

c) Ribo viruses

d) none of these

69. The smallest virus is of

79. Wound tumour virus contains

a) 20 nm.

b) 10 nm.

a) Double stranded DNA

c) 1 nm.

d) 2 nm,

b) Single stranded DNA

c) Double stranded RNA

70. Largest virus is

a) 100 nm.

b) 200 nm.

d) Single stranded RNA

c) 300 nm.

d) 400 nm.

80. Cyanophages were discovered by

71. Largest virus is

a) Safferman and Morris

b) Jacob and Monad

a) Penicillium virus

c) Lerderberg and Tatum

b) Wound and tumour virus

d) Lederberg and Zinder

c) Pox virus

81. A phage that invades but does not destroy the host
is known as

d) none of these
a) Sexduction

b) Phycophage

c) Virulent phage

d) Temperate phage

72. Algal viruses are known as

a) Binal viruses

b) Cynophages

c) Mycophages

d) Phycophages

82. Viruses differ from living organisms because

a) They can grow inside a living host.
73. Arthropod borne viruses are known as
b) They can multiply inside a living host.
a) Riboviruses

b) Reoviruses

c) Arboviruses

d) none of these

c) They can undergo mutation inside a living host.

d) They are non cellular.
74. In which of the following RNA acts as the genetic
material ?

83. Roux sarcoma virus contains

a) Coliphages

b) T.M.V.

a) RNA

b) DNA

c) Dahlia mosaic viruses

d) Rhizobium

c) DNA or RNA

d) none of these

75. Naked DNA viruses are known as

84. Viruses causing poliomyelitis and Rabies are

a) Deoxy vira

b) Herpes viruses

a) Neurotropic

d) Dermotropic

c) Ribo vira

d) Adenoviruses

c) Viscerotropic

d) Pneumotropic

76. Viral DNA if incorporated inside the host DNA is

known as

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85. In lysogenic viruses, the mode of infection is

a) Virulent

b) Temperate

c) Intermediate

d) all the above

94. When the viral genome gets integrated with the

bacteria genome, the state is called as

86. Harshey and Chase showed that

a) Prophage

b) Adsorption

c) Genome synthesis

d) Lysogeny

a) Penetration of viral DNA into host cells causes

infection

95. LPP-1 is the name given to

b) Viruses can be crystallized

a) Animal virus

b) Bacterio phage

c) Viruses cause several diseases

c) Rickettsia

d) Cyanophage

d) viruses consist of nucleo proteins

96. The nucleic acid of viruses is called as

87. Lysogenic bacteria are

a) Prophage

b) Virion

a) bacteria which infect other hosts in a viral manner

c) Nucleoid

d) Capsid

b) bacteria containing prophage

97. The preparation of an effective common cold

vaccine has not yet been possible because

c) bacteria which cause diseases in plants only

it is caused by

d) bacteria which parasitize other bacteria

88. What is absent in viruses
a) cytoplasm

b) mitochondria

c) golgi bodies

d) all the above

a) Rickettsia

b) Live virus

c) Numerous

d) Spiroplasma

98. Mycoplasma was discovered by

a) Zinder and Lederberg

89. In which virus there is a membranous covering of

proteins, lipids and carbohydrates.

b) Nocard and Roax

c) Jacob and Wollman

a) bacteriophage

b) Influenza virus

d) Lederberg and Tatum

c) TMV

d) Myxovirus

99. Penicilin has no effect on

90. A lysogenic type of virus is

a) pus forming bacteria

a) lambda phage of E.Coli

b) albugo

b) Various pathogenic bacteria

c) Rhizophora

d) Noctiluca

c) Mycoplasma

91. Death of bacterium accompanied by liberation of

large number of virus particles takes place during
a) lytic cycle

b) Lysogenic cycle

c) Viral cycle

d) Phage cycle

d) chlamydieae
100. A chilkless parent went to the hospital for
consultation. The doctor doubted the presence of
infertility in him due to the disease caused by
a) Spirochaetes

92. The life cycle in which viruses do not multiply and

no death of host cell occurs is called as

b) Mycoplasma hominis

a) Lytic cylce

b) Viral cylce

c) Pseudomonas xanthi

c) Phage cycle

d) Lysogenic cycle

d) Closteridium botylicum

93. In viral life cycle a kind of symbiotic association

develops during
a) Adsorption

b) Injection

c) Lysogeny

d) Maturation

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IMPORTANT QUESTIONS
1. Describe the structure of a bacterial cell.
2. Explain various modes of nutrition in bacteria.
3. Describe various processes of genetic recombination in bacteria.
4. Comment on the statement that 'Bacteria are our friends and foes'.
5. Give a brief description of food preservation methods.

Answer Objective Problems :

Answers Towards Perfection:

1a

2d

3c

4a

5a

6d

1b

2c

3a

4a

5d

6a

7a

8c

9d

10b

11c

12a

7d

8d

9c

10d

11a

12d

13d

14b

15d

16d

17a

18c

13a

14d

15a

16b

17a

18c

19a

20b

21d

22c

23b

24b

19c

20c

21c

22b

23c

24b

25b

26d

27b

28c

29d

30b

25b

26c

27d

28b

29c

30b

31a

32c

33d

34d

35a

36d

31b

32a

33d

34d

35a

36b

37c

38c

39a

40d

41a

42d

37a

38b

39a

40a

41b

42a

43d

44b

45b

46a

47d

48a

43b

44d

45a

46a

47b

48c

49a

50a

51b

52c

53a

54a

49b

50d

51d

52d

53c

54a

55c

56d

57c

58b

59b

60d

55a

56b

57d

58a

59b

60c

61b

62d

63a

64d

65c

66c

61a

62c

63c

64b

65c

66b

67b

68d

69b

70c

71a

72b

67d

68a

69a

70c

71c

72d

73a

74c

75a

76b

77a

78b

73c

74b

75d

76a

77a

78d

79b

80b

81c

82c

83b

84a

79c

80a

81d

82d

83a

84a

85a

86d

87b

88c

89b

90d

85b

86a

87b

88d

89b

90a

91a

92b

93a

94a

95c

96a

91a

92d

93c

94a

95d

96c

97b

98d

99d

100d

97b

98b

99c

100b

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