1.

0 INTRODUCTION

Archaebacteria is the first kingdom in the six kingdom classification of living things. The word

Archae simply means ancient. This kingdom contains organisms at the simplest level of

organization. They are prokaryotes, who were previously in the kingdom Monera but now

recognized as being genetically and structurally distinct, forming their own domain, Archaea.

Unlike bacteria, archaea lack peptidoglycan in their cell walls and have unusual (ether-linked) lipids

in their cell membranes which are not found in any other group of organisms. .This group ofsingle

celled organisms live under extreme conditions like no oxygen and very high temperatures. The

structure and function of the genes in archaea are similar to the structure and function of the genes

in eukaryotes, while those of eubacteria are not.

2.0 Objectives

At the end of this chapter you should be able to

1. State the diagnostic features of the kingdom

2. Identify the major phyla of Archaebacteria

3. Differentiate the three groups of Archaebacteria

4. Know the observable adaptive features of the archaebacteria.

3.0 Main Body

3.1. Diagnostic Features of Archaebacteria

Archaebacteria have no peptidoglycan in their cell walls

The cell wall is made up of glycoproteins and polysaccarides.

The cell wall envelopes have a high resistance to antibiotics and lytic agents due to difference

in cell wall composition.

They have a very different lipid bilayer making up the cell membranes

The RNA polymerase of archae is very similar to that of eukaryotes

The eukaryotes and archea ribosomal proteins are similar to each other

Archaebacteria are about 1/10th of a micrometer to about 15 micrometer in size. A few are

flagellated and the flagella structure is different from the flagella of other bacteria.

The archaebacteria are non-pathogenic bacteria that live in and around other organisms.
Archaebacteria are autotrophs and use CO2 in atmosphere as a source of carbon for a process

called carbon fixation.

3.2 Classification of Archaebacteria.

The archae are currently placed in four phyla, they are

Eurychaeota e.g Pyrococcus abysi

Crenarchaeota e.g sulfolobus acidocaldarius

Nanoarchaeota e.g Nanoarchaeum equitans

Korarchaeota

3.3 MORPHOLOGY

Figure 1.1 An Archae Retrieved from "http://en.wikipedia.org/wiki/File:RT8-4.jpg

Fig 1.2 Halobacteria Retrieved from "http://en.wikipedia.org/wiki/File:Halobacteria.jpg"

Archaebacteria cells have diameters which range from about 0.0002–0.0004 in (0.5–1.0

micrometer). The volume of their cells is only around one-thousandth that of a typical eukaryotic

cell. They have three main forms or shapes

1) Spherical cells called cocci,

2) Rod shaped cells called bacilli,

3) spiral shaped cells which can either be vibrio, spirillum , or spirochete

4) Some other shapes may occur such as irregularly shaped lobed cells , needle-like filaments ,

almost perfectly rectangular rods , flat, square archaea , and filaments form aggregates or filaments

and multicell colony

3.4. STRUCTURE

Archaebacteria, like all prokaryotes, have no membrane bound organelles. This means that the

archaebacteria are without nuclei, mitochondria, endoplasmic reticula, lysosomes, Golgi complexes,

or chloroplasts. The cells contain a thick cytoplasm that contains all of the molecules and

compounds of metabolism and nutrition . Archaebacteria have a cell wall that contains no

peptidoglycan. This rigid cell wall supports the cell, allowing an archaebacterium to maintain its

shape, and protecting the cell from bursting when in a hypotonic environment. Because these

organisms have no nucleus, the genetic material floats freely in the cytoplasm. The DNA is a single

circular molecule. This molecule is tightly wound and compact, and if stretched out would be more

than 1,000 times longer than the actual cell. Little or no protein is associated with the
DNA. Plasmids may be present in the archaebacterial cell. These are small, circular pieces of DNA

that can duplicate independent of the larger, genomic DNA circle. Plasmids often code for particular

enzymes or for antibiotic resistance.

3.5 HABITAT

These organisms live in extreme environmental conditions, such as very high temperatures, (above

100 °C) and in the absence of oxygen and light （ therefore are also known as extremophiles）

Specific examples includes

1) Near volcanic activity2) Geysers, black smokers and oil wells 3) Deep oceans4) Very cold

habitats 5) highly saline ,acidic, or alkaline water.6) Marshland 7)Sewage 8)Soils

9) Gut of humans and ruminants.

3.6 ARCHAEBACTERIA GROUPS

Archaebacteria are autotrophs and use CO2 in atmosphere as a source of carbon for a process called

carbon fixation. They employ different chemical reactions to be able to survive in these harsh

conditions. Based on the nature of their habitats the archae are grouped into three , these are

1. Methanogens

2. Halophiles

3. Thermoacidophiles.

Methanogens:- they can reduce carbon dioxide into methane. They can only survive in the absence

of oxygen. They produce marsh gas that one can observe as bubbles in stagnant waters. They are

also present in the gut of cattle and termites. These bacteria are rod shaped or spherical and can be

gram positive as well as negative.eg Methanobacterium, Methanococcus, Methanomicrobium

Halophiles :- they are found in areas with very high salt concentrations sea. They contain

bacteriorhodopsin, a red or orange pigment.eg Halobacterium,Halococcus, Natronabacterium

Thermoacidiophiles :- Organisms that can survive in extremely high temperatures and low pH.
They can survive at 100° Celsius with a pH of 2. Most of these organisms are anaerobic nature e.g

Pyyrodictium, Pyrococcus, Sulfolobus, thermococcus, thermoproteus.

3.7 ADAPTIVE FEATURES

Archaebacteria do not form spores and a few species of haloarchae undergoes phenotypic switching.

This means it can grow several different cell types that are resistant to osmotic shock. Thus, the

organisms can survive in low salt concentration aquatic environments.

3. 8 ACTIVITY

A) 0bserve Fig2.1 and 2 .2.What diagnostic feature of the Archae can you see?

B) Observe prepared slides of the archae bacteria make labeled diagrams of your

observations

C) Visit a stagnant water site especially in a swamp. Can you observe any bubbles?
D) What group of organisms are responsible for the bubbles in B above

In Text Question
What are Halophiles?
Answer: Halophiles are archaebacteria found in areas with very high salt concentrations sea
4.0 Conclusion
The Archaebacteria simply means ancient bacteria. They are believed to be one of the first
group of living things to occupy the earth. They are prokaryotes and have been found in
habitats otherwise thought of as inhabitable

5.0 Summary
In this unit you have studied the habitat , diagnostic features , structure, morphology

,classification, groups and adaptive features of the phylum Archaebacteria.. they are prokaryotic

organisms. They have the special ability to stay in areas with extremes of temperature and pH

conditions as well as in the absence of oxygen. They do not have peptidoglycan in theircell walls.

They have unusual (ether-linked) lipids in their cell membranes which are not foundin any other

group of organisms. Based on the nature of their habitat archae are grouped into three viz

Methanogens

. Halophiles Thermoacidophiles. examples of organisms in this group are Pyrococcus abysi

6.0 Tutor-Marked Assignment
a ) List the types of habitat in which Archaebacteria are found?

b) Which features of the Archae help them adapt to harsh condition

c) Make labeled drawing of the Haloarchae

7.0 REFERENCES/FURTHER READING

Batul N. B. (2010). Archaebacteria kingdom Information.

http://www.buzzle.com/authors.asp?

http://science.jrank.org/pages/476/Archaebacteria-html

http://en.wikipedia.org/wiki/Archaea"

http://www.daviddarling.info/index.html

7Raven, P.H and Johnson,B.G.(1995) “The Invisible World Bacteria and Viruses’.Undrestanding

Biology 3rd Edition McGraw Hill Publ U.S.A .Pg 491-504

UNIT 2 THE KINGDOM EUBACTERIA

CONTENTS

1.0 Introduction

2.0 Objectives

3 .0 Main Body

3.1 Habitat

3.2 Classification

3.3 Morphology

3.4 Structure

3.5 Adaptive features

3.6 Activity
4.0 Conclusion
5.0 Summary
6.0 Tutor-Marked Assignment
7.0.References/ Further readings
1.0 INTRODUCTION

In the last unit, you learnt about archaebacteria. In this unit we shall consider the Kingdom Eubacteria
This is the second kingdom in the six kingdom classification of living things. They are also known

as the true bacteria. They are prokaryotes and a lot of them live as single cells, but they are able to

produce colonies or link up in chains to form filaments.

2.0 OBJECTIVES

At the end of this unit the students should

A) Know the methods of classification of the Eubacteria

B) Know the diagnostic features of the Eubacteria,

C) Know the differences between the gram positive and gram negative bacteria.

D) Know the adaptive features of the Eubacteria

3.0 MAIN BODY

3.1 Habitat

The Eubacteria are cosmopolitan, they live everywhere, soils, water, faeces, decaying substances,

bodies of plants and animals.

3.2 Classification

There are three main criteria used to classify the Eubacteria, they are

Shape

It is easy to distinguish the Eubacteria based on their shape. Bacterial cells have three main

shapes:

1) Cocci: round with bumps

2) Bacilli: rod-shaped with lacerations

3) Spirilli: spiral-shaped with grooves

Furthermore, bacteria can be classified by their growth characteristic patterns (Groupings). The

prefix diplo- means that the cells are arranged in pairs. The prefix staphylo- means that the
bacterial cells are arranged in clusters like grapes. The prefix strepto- means that the bacteria are

arranged in a chain.

Figure 2.1 :Common shapes of eubacteria Retrieved at http://www.sparknotes

2. Type of cell wall structure

1) Gram-positive: Gram-positive bacteria have simple cell walls, that are made up of only one layer

of peptidoglycan before the plasma membrane. When stained with violet and red dye, gram-positive

bacteria appear purple. Sometimes blue, depending on the temperature.

2) Gram-negative: Gram-negative bacteria have more complex cell walls, consisting of one layer of

a lipopolysaccharide membrane and a peptidoglycan layer. Gram-negative bacteria appear red when

stained with violet and red dye.

3 Carbon and Energy Sources

a) Photoautotrophs b) Photoheterotrophic c)Autotrophic d) Heterotrophic

3.3 Structure
Figure 2.2 Retrieved at http://www.sparknotes

Eubacteria have prokaryotic chromosomes, which have circular DNA molecules called plasmids.

They do not have a nuclear membrane, instead they have plasmids, that can be seen in

relativelyclear areas in the cytoplasm called nucleoids. The rest of the cytoplasm is filled with

ribosomes.

Many eubacteria have specialized internal membranes. For example, cyanobacteria have

membranes that contain chlorophyll and other chemicals used to carry out photosynthesis.

Many eubacteria have cell walls that lie outside of their plasma membranes. These are similar to the

cell walls found in plants and fungi, but are made of peptidoglycan rather than cellulose or chitin.

In some eubacteria, this cell wall is covered by another layer called the outer membrane. Many

eubacteria have yet another coating layer called a capsule. It is made up of complex sugars and

serves to protect the cell against environmental dangers, such as attack by host immune defenses or

dehydration.
Comparison of the Archaebacteria and the Eubacteria

Archaebacteria Eubacteria
Single celled organisms All true bacteria or group of
Definition: without any cell organelles or unicellular prokaryotic
nucleus. microorganisms.
Various shaped bacteria have
Occur in various shapes like
been identified like rods,
Morphology: spheres, rods, plates and
cocci, spirals, comma
spirals.
shaped, tightly coiled etc.
Cell Wall: Lack of peptidoglycan . Peptidoglycan is present.
Branched chain ether linked Straight chain ester linked
Cell Membrane:
lipids. lipids.
tRNA: Lacks thymine in tRNA. Thymine present in tRNA.
Ten subunit RNA polymerase Ten subunit RNA
RNA polymerase:
core. polymerase core.
Role in bio-geochemical
Role in ecology: Vital in nutrient recycling.
cycles is unexplored.
Interactions with other Predators, mutualists,
Mutualism, commensal
organisms: pathogens.
Pathogenicity: None are pathogenic. Some are pathogenic.
Fermented foods,
Thermostable enzymes, bioremediation, waste
Significance in technology sewage treatment, antibiotics, processing, agrichemicals,
and industry: organic solvents, production of biological pest control,
biogas. scientific research.

Source : http://www.diffen.com/difference/special:ArticleList

3.5 Adaptive Features

1. Shape Spiral shaped bacteria can move through fluids more easily than can cocci or bacilli

bacteria.

2. Plasmids Bacteria contain plasmids, that can be transmitted from one cell to another. 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.

3. Capsule protects the cell against environmental dangers, such as attack by host immune

defenses or dehydration.

4. Endospore – These are formed when surrounding conditions are unfavorable and are for

protection .thick walled endospores

5. Outer membrane- Increases the potential surface area for photosynthesis

3.6 ACTIVITY

A) To stain bacteria for examination with a light microscope. (Gram’s method).

This staining procedure is very important because it helps in the recognition and identification of

bacteria. It separates nearly all bacteria into two groups either as Gram’s positive or Gram negative

. This is based on whether or not they resist decolourization of methyl violet and subsequent

treatment with iodine.

Procedure

Make a smear of the bacteria culture given to you(or which you have prepared) on a clean grease

–free slide.

Air-dry the film by waving it around for a while.

Heat fix the smear by waving it over a bunsen flame.

Then place the slide on a rack over a sink.

Cover the smear with crystal violet reagent for one minute.

Rinse the slide in a slowly running tap for 5 seconds.

Then rinse the slide with Gram’s Iodine and flood it with the same reagent for1 minute.

Rinse again in a slowly running tap.

Apply alcohol reagent slowly until no more dye runs off from the smear

Cover smear with Safranin(or Carbol Fuchsin) reagent for 30 seconds

Rinse slide under slowly running water

Blot dry using paper towel

NB Blot, don’t rub

Observe the slide using the oil immersion lens of the Microscope.

Record your observations

What are the differences between the gram positive and gram negative bacteria?

B) Shapes of bacteria
Procedure

i) With the sterile loop, take a small portion from bacterial colonies you have

grown or provided for you and smear this evenly on a microscope slide. Fix over a flame by

passing the under surface of the slide swiftly through the top of a flame.

ii) Flood the dried smear with either methylene blue or crystal violet and leave for

3 minutes.

iii) Drain dry.

iv) Lower a cover slip over the preparation and observe under the microscope.
You will see the cultured bacteria .

In Text Question
Give the shape of cocci, bacilli and spirilli bacteria respectively
Answer: Their shapes are, round, rod-shaped and spiral respectively.
4.0 Conclusion
The Eubacteria also known as the true bacteria are prokaryotes. They are cosmopolitan being found
everywhere and in the bodies of plants and animals. They cannot be seen with the naked eye being
microscopic.
5.0 Summary
In this unit you have studied the habitat , diagnostic features , structure, morphology, classification

and adaptive features of the Kingdom Eubacteria. They are known as the true bacteria and are also

prokaryotes and microscopic. They are found everywhere. Major criteria used in their classification

is the reaction to Gram’s staining .All bacteria are either Gram positive or negative. common

examples Also very important to their taxonomy and nomenclature is their shapes. , Cocci or

round , Bacilli: rod-shaped, Spirilli: spiral-shaped .Common examples of

of Bacteria include Anabaena, Rhizobium,Neisseiria gonorrhoeae, Treponema palladium.

6.0 Tutor-Marked Assignment
How many shapes can you identify?

Make labeled drawings of your observations.

Submit your books for assessment and evaluation.

7.0 REFERENCES/FURTHER READINGS

http://www.biology-online.org/dictionary/Eubacteria

http://en.wikipedia.org/w/index.php?title=Bacteria&oldid=339872217

http://en.wikipedia.org/w/index.php?title=Archaea&oldid=340346738

http://www.foamtecintlwcc.com/google/decontamination.html Retrieved from

"http://en.wikibooks.org/wiki/General_Biology/Classification_of_Living_Things/Eubacteria"

Category:

General Biology Retrieved from

"http://en.wikibooks.org/wiki/General_Biology/Classification_of_Living_Things/Eubacteria

http://www.sparknotes.com/biology/microorganism/monera/citing.

Iloeje,S.O.(1991). “Cells and Some microscopic organisms”Senior Secondary Certificate

Practical Biology Longman Nigeria Publ pg9-11

Isu N.R and Onyeagba,R.A (1998) . “ Staining of Microbial cells “ Basic practicals in

Microbiology Fasmen Communications, Owerri pg 45

Raven, P.H and Johnson,B.G.(1995) “The Invisible World Bacteria and Viruses’.Undrestanding

Biology McGraw Hill Publ Pg 491-504

Taylor,D.J.,Green,N.P.O.,Stout,G.W.(1998). “Staining Bacteria ”Biological Science Cambridge

University Press U.K pg 388

UNIT 3 THE KINGDOM PROTISTA

CONTENTS

1.0 Introduction

2.0 Objectives

3.0 Main Body

3.1 Habitat

3.2 Classification

3.3.1 The protozoan Protists

3.3.2 The algal Protists

3.3.3 The fungal Protists

3.4 Adaptive features

3.5 Activity
4.0 Conclusion
5.0 Summary
6.0 Tutor-Marked Assignment
7.0.References/ Further readings