Characterization

and Classification of
Eukaryotes
PROTOZOA
Characteristics shared by all protozoa:
•eukaryotic
•unicellular
•lack cell walls
•free-living; parasitic;
•2-20,000 micrometer

Distribution of Protozoa:
•moist environment

Morphology of Protozoa:

pleomorphic
trophozoite - motile; feeding stage;
diagnostic stage

cysts - dormant; resting stage;

infective stage; with
low metabolic rate

Nutrition of Protozoa:
chemoheterotrophic- obtain nutrients by phagocytizing
bacteria, decaying organic matter, other protozoa, or the
tissues of the host; a few absorb nutrients from the
surrounding water.
photoautotrophic
Reproduction of Protozoa:

* asexually - Binary Fission

(longitudinal BF-flagellated)

(transverse BF- ciliated)

*sexually - Conjugation
(paramecium)
 Classification of Protozoa:

* based on their locomotory structures (before) and based on nucleotide

sequencing

1. Sarcodina (pseudopodia)

2. Mastigophora (flagella)
- THE LARGEST GROUP

3. Ciliophora (cilia)

4. Sporozoa (nonmotile)
-ALL pathogenic to humans
Classification of Protozoa

I. Alveolates
- with small membrane-bound cavities called alvioli.
- share at least one characteristic-tubular mitochondrial cristae

A. Ciliates (Balantidium , Paramecium, Stentor, Vorticella, Didinium)

- have cilia by which they either move themselves or move water past
their cell surfaces
Classification of Protozoa

B. Apicomplexans (Babesia, Plasmodium Toxoplasma, Cryptosporidium)

- are all pathogens of animals; the name of this group
refers to the complex of special intracellular organelles,
located at the apices of the infective stages of these
microbes, that enable them to penetrate the host cells.
Plasmodium spp.
Classification of Protozoa

B. Apicomplexans (Toxoplasma)
Classification of Protozoa

C. Dinoflagellates (Gymnodinium, Gonyaulax, Pfiesteria)

- like many plants and algae their food reserves are starch and oil, and
their cells are often strengthened by internal plates of cellulose.

- historically classified as algae because of their plant-like features,

taxonomist today note their 18S rRNA sequence and the presence of
alvioli indicate that they are more closely related to ciliates and
apicomplexans than they are to either plants or algae.

Many dinoflagellates are BIOLUMINESCENT; photoautotrophic

Peridinium (dinoflagellate)
Red Tide (red pigment)
- 50,000 cells/ml
- a neurotoxin (0.5mg)

e.g. Gymnodinium and Gonyaulax

- Ingestion of shell fish (have planktonic

dinoflagellates)

PEAS (Possible Estuary-Associated Syndrome)

- Pfiesteria, another toxin (Lois Pfiester)
- Handling infected fish; breath air laden
with the microbes
- May cause memory loss, confusion,
headache, respiratory difficulties, skin rash,
muscle cramps, diarrhea, nausea and
vomiting.
Classification of Protozoa

II. Amoebae (Foraminifera, Radiolarians, Free-living types, Parasitic types)

A. (Cercozoa) Foraminifera
- has a porous shell composed of calcium carbonate arranged on an
organic matrix in a snail-like manner.
- pseudopodia extend through the holes in the shell
- lived attached to sand grains on the ocean floor.
- mostly microscopic, though scientist have discovered species several
cm in diameter.
Classification of Protozoa

II. Amoebae (Radiolarians)

B. Radiolaria

- thread-like pseudopodia , have ornate shells of silica; live in marine

water as part of the plankton

- the dead bodies of radiolarians settle at the bottom of the ocean

where they form ooze that is hundreds of meters thick in some
locations.
Classification of Protozoa

II. Amoebae

C. Amoebozoa (Free-living types, Parasitic types)

- have a lobed –shaped pseudopodia and no shells

Free-living types Parasitic Types

 Slime Molds

- Was formerly considered another group of amoebozoa-to be fungi, but the lobe-
shaped pseudopodia by which they feed and move as well as their nucleotide
sequences show that they are amoebozoa.
- There are two types of slime molds: plasmodial molds and cellular molds.

Slime molds differ from true fungi in two main ways:

(1) They lack cell walls, more closely resembling amoebae in this regard.

(2) They are phagocytic rather than absorptive in their nutrition.

- Species in the two groups of slime molds differ based on their morphology,
reproduction, and 18SrRNA sequences.

- Slime molds are important to humans primarily

as excellent laboratory systems for the study of
developmental and molecular biology.
 Plasmodial (Acellular) Slime Molds (e.g. Physarum)

- Exist as streaming, coenocytic, colorful filaments of cytoplasm that creep as amoebae

through forest litter, feeding by phagocytizing debris and bacteria.
 Cellular Slime Molds (Dictyostelium)

- Exist as individual haploid myxamoebae that phagocytize bacteria, yeast, dung, and
decaying vegetation.
Classification of Protozoa

III. Euglenozoa

- Part of the reason that taxonomist established the Kingdom Protista in the
1960’s was to create a “dumping ground” for euglenids; eukaryotic microbes that
share certain characteristics of both plants and animals.

- Most recently, based on similar 18S rRNA sequences, the presence of

mitochondria with disc-shaped cristae, some taxonomist have created a new
taxon: Kingdom Euglenozoa which include euglenids and some flagellated
protozoa called kinetoplastids.
Classification of Protozoa

III. Euglenozoa
A. Euglenids
- photoautotrophic, unicellular microbes with chloroplasts containing
light absorbing pigments-chlorophyll a and b and carotene. It is for this
reason that botanist historically classified euglenids in the Kingdom
Plantae.

- One reason for not including euglenids with plants is that euglenids
store food as a unique polysaccharide called paramylon instead of
starch.

- Similar to animals in that they lack cell walls, have flagella, are
chemoheterotrophic phagocytes (in the dark) and move by using their
flagella as well as by squirming movement which is similar to amoeboid
movement but does not involved pseudopodia (euglenoid movement).

- has flexible, proteinacious, helical pellicle that underlines its cytoplasmic

membrane and helps maintain its shape.

- Typically has a “red eye”, which plays a role in positive phototaxis.

Classification of Protozoa

III. Euglenozoa

B. Kinetoplastids (Trypanosoma and Leishmania)

- have a single large mitochondrion that contains a unique region of

mitochondrial DNA called a kinetoplast,

- they live within animal, and some are pathogenic.

Classification of Protozoa

IV. Diplomonads
- lacks mitochondria, golgi apparatus, and peroxisomes.
- Biologist once thought these organisms were descended from ancient
eukaryotes that had not yet phagocytized the prokaryotic ancestors of
mitochondria.
- Geneticist have recently discovered rudimentary mitosomes in the cytoplasm
and mitochondrial genes in the nuclear chromosomes, a finding that suggests
that diplomonads might be descended from typical eukaryotes that somehow
lost their organelles

A. Giardia
Classification of Protozoa

IV. Diplomonads

B. Microsporidia (Nosema)
Classification of Protozoa

V. Parabasala
- also lack mitochondria, but each has a single nucleus and a parabasal body,
which is a golgi body-like structure.

A. Trychonympha

Inhabits the gut of termites

where it assist in the digestion
of wood.
Classification of Protozoa

V. Parabasala

B. Trichomonas
 FUNGI

The absence of photosynthesis and the lack motility are the characteristics of
fungi. They differ from plants in that they lack chlorophyll and do not perform
photosynthesis; they differ from animals by having cell walls; genetic sequencing
have shown that fungi and animals are related.
Morphology of Fungi
Morphology of Fungi
Fungial mycelium
Reproduction of Fungi
Chlamydospores Conidospores
Sexual Spores
The Process of Sexual Reproduction in Fungi
The Life Cycle of the Zygomycetes, Rhizopus
The Life Cycle of an Ascomycete, Penicillium
The absence of photosynthesis and the lack of motility
are the characteristics of fungi.
 I. Division Zygomycota

- are coenocytic molds called zygomycete; of the approximately 1100 species

known, most are saprobes, the rest are obligate parasites of insects and other
fungi.
- Until 2003, taxonomist have thought microsporidia were protozoa, but
genetic analysis indicates they are more similar to zygomycetes; they are
obligatory intracellular parasites an example is Nosema, which is parasitic on
insects such as silkworms and honeybees.
- EPA has approved one species of Nosema as a biological control agent for
grasshoppers.
- Seven genera of microsporidia, including Nosema and Microsporidium are
known to cause diseases in immunocompromised patients.
I. Division Zygomycota
A. Rhizopus (Black bread mold)
The absence of photosynthesis and the lack motility
are the characteristics of fungi.
 II. Division Ascomycota
The division Ascomycota contains about 32,000 known species of molds and yeast that
are characterized by the formation of haploid ascospores within sacs called asci. Asci occur
in fruiting bodies called ascocarps, which have various shapes. Ascomycetes as they are
called, also reproduce asexually by conidospores (e.g. Penicillium)
 II. Division Ascomycota
Ascomycetes are familiar and economically important fungi. For example, most fungi that
spoil food are ascomycetes.

This group also includes that pathogens such as the causative agents of Dutch elm disease
and chestnut blight, which have almost eliminated their host trees in many parts of the
United States.
 II. Division Ascomycota
A. Claviceps
Claviceps purpurea

- grows as hyphae on kernels of rye, wheat and barley produces a substance called
ERGOT- an alkaloids;

- products such as bread made from rye grain may cause ergot rye disease called
ERGOTISM- manifested with the following symptoms; numbness, hot and cold
sensations, convulsions with epileptic-type seizures and paralysis of the nerve
endings.
 II. Division Ascomycota
B. Saccharomyces, Penicillium, Tuber (Truffles)

Many Ascomycetes are beneficial. For example, Penicilliun mold is the source of
penicillin;

Saccharomyces, which ferments sugar to produce alcohol and carbon dioxide gas, is the
basis of the baking and brewing industries;
 II. Division Ascomycota
C. Tuber

Truffles (varieties of Tuber) grow as mycorrhizae in association with oak and beech trees
to form delectable culinary delights.

Black truffle – “black diamond”

Ascocarps (fruiting bodies) of the common morel, Morchella esculenta, a
delectable edible ascomycete.

The pits visible in this photograph are lined with asci, sacs that contain numerous
ascospores.
II. Division Ascomycota
D. Neurospora
Another ascomycete, the pink bread mold Neurospora, has been an important
tool in genetics and biochemistry.

Many ascomycetes partner with green algae or cyanobacteria to form lichens.

The absence of photosynthesis and the lack motility
are the characteristics of fungi.
 III. Division Basidiomycota
A. Agaricus
B. Cortinellis
C. Cryptococcus

A walk through fields and woods in most parts of the world may reveal
mushrooms, puffballs, stinkhorns, jelly fungi, bird’s nest fungi, or bracket fungi,
all of which are the visible fruiting bodies of the almost 22,000 known species of
fungi in the division Basidiomycota.
 III. Division Basidiomycota
A. Agaricus
B. Cortinellis
C. Cryptococcus

A walk through fields and woods in most parts of the world may reveal
mushrooms, puffballs, stinkhorns, jelly fungi, bird’s nest fungi, or bracket fungi,
all of which are the visible fruiting bodies of the almost 22,000 known species of
fungi in the division Basidiomycota.
Mushrooms and other fruiting bodies of basidiomycetes are called Basidiocarps. The
entire structure of a basidiocarp consist of tightly woven hyphae that extend into
multiple, often club-shaped projections called basidia, the ends of which produce sexual
basidiospores (typically four of each basidium). (Amanita muscaria)

Basidiocarps (fruiting bodies) of the bird’s nest fungus, Crucibulum. The familiar shapes of
mushrooms are also basidiocarps of extensive mycelia.
 III. Division Basidiomycota
A. Agaricus
B. Cortinellis
C. Cryptococcus
A walk through fields and woods in most parts of the world may reveal
mushrooms, puffballs, stinkhorns, jelly fungi, bird’s nest fungi, or bracket fungi,
all of which are the visible fruiting bodies of the almost 22,000 known species of
fungi in the division Basidiomycota.
III. Division Basidiomycota

D. Amanita
 Amanita muscaria – “death-cap mushroom”

Question: How can a novice distinguish between edible and poisonous mushrooms?
Basidiomycetes
 III. Division Basidiomycota
A. Agaricus
B. Cortinellis
C. Cryptococcus
Besides the edible mushrooms-most notable, the cultivated Agaricus and
Cortinellis which affect humans in several ways.

Most Basidiomycetes are important decomposers that digest chemicals such as

cellulose and lignin in dead plants and return nutrients to the soil.

Many mushrooms produce hallucinatory chemicals or toxins. An example of the

latter is the extremely poisonous “Death –cap Mushroom,” Amanita .
 III. Division Basidiomycota
A. Agaricus
B. Cortinellis
C. Cryptococcus

Besides The Basidiomycete yeast Cryptococcus neoformans is the leading cause

of fungal meningitis.

Other basidiomycetes are rusts and smuts, which causes millions of dollars in
crop loss each year.
The absence of photosynthesis and the lack motility
are the characteristics of fungi.
 IV. Division Deuteromycetes
The Fungi Imperfecti or the Imperfect Fungi

Because scientist have not observed sexual reproduction in all fungi, taxonomists
in the middle of the 20th century created the division Deuteromycota to contain
the fungi whose sexual stages are unknown-either because they do not produce
sexual spores or because their sexual spores have not been observed.

More recently, however, the analysis of rRNA sequences has revealed that most
deuteromycetes in fact belong in the division Ascomycota, and thus modern
taxonomists have abandoned Deuteromycota as a formal taxon. Nevertheless,
many medical laboratory technologists, health care practitioners, and scientist
continue to refer to ”deuteromycetes” because it is a traditional name.

Most deuteromycetes are either terrestrial saprobes, pathogens of plants, or

pathogens of other fungi. Several genera are pathogenic to humans.

There are 25,000 species have been identified.

IV. Division Deuteromycetes
IV. Division Deuteromycetes
 IV. Division Deuteromycetes
A. Histoplasma
- Agent of Histoplasmosis (Systemic Disease-pulmonary, cutaneous, ocular, systemic)
- found in moist soil containing high levels of nitrogen (from droppings of bats, and
birds, especially chickens, starlings, and blackbirds) prolonged exposure to these may
be hazardous the disease does not affect birds or bats
IV. Division Deuteromycetes

B. Trychophyton

-agents of ringworm infections

Lichens
 Lichens
Lichens, forms partnerships between fungi and photosynthetic microbes-either green algae
or, commonly, cyanobacteria.

In a lichen, the hyphae of the fungus, which is usually an ascomycete, surround the
photosynthetic cells and provide them nutrients, water and protection from desiccation
and harsh light.

In return, each alga or cyanobacterium provides the fungus with products of

photosynthesis-carbohydrates and oxygen. In some lichens, the phototroph releases 60%
of its carbohydrates to the fungus.
 Lichens
The partnership in a lichen is not always mutually beneficial; in some lichens, the fungus produces
haustoria that penetrate and kill the photosynthetic member. Such lichens are maintained only
because the phototroph’s cells reproduce faster than the fungus can devour them.

The fungus of a lichen reproduces by spores, which must germinate and develop into hyphae that
capture an appropriate alga or cyanobacterium. Alternately, wind, rain, and small animals disperse
bits of lichen called soredia, which contain both phototrophs and fungal hyphae, to new locations
where they can establish a new lichen if there is suitable substrate.
 Lichens
Scientist have identified over 14,000 species of lichens. Lichens are abundant throughout
the world, particularly in pristine unpolluted habitats, growing on soil, rocks, leaves, tree
bark, other lichens, and even backs of tortoises.

Lichens grow in almost every habitat-from high-elevation alpine tundra to submerged

rocks on the ocean’s shores from frozen Antarctic soil to hot desert climes.

The only unpolluted places where lichens do not consistently grow are in the dark depths
of the oceans and the back world of caves-after all, lichens require light.
 Lichens
Lichens grow slowly but they can live for hundreds and possibly thousands of years.

They occur in three basic shapes:

(1) Fruticose - either erect or hanging cylinders.

(2) Crustose - grow appresed to their substrates and may extend into the
substrate for several millimeters.

(3) Foliose - leaf-like with margins that grow free from substrate.
Lichens
Lichens are important agents in :

(1) the creation of soil from weathered rocks

(2)and lichens containing nitrogen-fixing cyanobacteria provide nitrogen

to nutrient-poor environments

(3)many animals eat lichens, for example, reindeer and caribou subsists
primarily on lichens throughout the winter

(4)birds use lichens for nesting materials, and some insects camouflage
themselves with bits of living lichens

(5)humans also used lichens in the production of food, dyes, clothing,

perfumes, medicines, and the litmus indicator paper. Because lichens
will not grow well in polluted environments, ecologists use them as
sensitive living assays for monitoring air pollution
 ALGAE

The Romans used the word alga to refer to any simple aquatic
plant, particularly one found in marine habitats.

Today, the word algae properly refers to simple, eukaryotic,

photosynthetic organisms that, like plants, carry out oxygenic
photosynthesis using chlorophyll a.

Algae differ from plants such as sea grass in having sexual

reproductive structures in which every cell becomes a gamete.

In plants by contrast, portion of the reproductive structure

always remains vegetative.
 DISTRIBUTION OF ALGAE
Even though some algae grow in such diverse habitats as in soil and ice, in
intimate association with fungi as lichens, and on plants; most algae are aquatic,
living in the photic zone (penetrated by sunlight) of fresh, brackish and salt
bodies of water.

Chlorophyll a captures red light; water absorbs longer wavelengths of light

(including red light), so only shorter (blue) wavelengths penetrate more than a
hundred meter below the surface. This is problematic for algae because they
capture red light.

Thus, to grow in deeper waters, algae must have accessory photosynthetic

pigments that trap the energy of penetrating, short-wavelength light and pass
that energy to chlorophyll a.

Members of the group of algae known as red algae, for example, contain
phycoerythrin, a red pigment that absorbs blue light, enabling red algae to
inhabit even the deepest parts of the photic zone.
 MORPHOLOGY OF ALGAE
Algae can be unicellular or colonial, or they can have simple multicellular bodies
called thalli, which are commonly composed of branched filaments or sheets.

The thalli of large marine algae, commonly called seaweeds, can be relatively
complex, with branched holdfast to anchor them to rocks, stem-like stipes, and
leaf-like blades. The thalli of many of the larger marine algae are buoyed in the
water by gas-filled bulbs called pneumocysts.

Though the thalli of some marine algae can surpass land plants in length, the lack
well-developed transport systems common to vascular plants.
 REPRODUCTION OF ALGAE

In unicellular algae asexual reproduction involves mitosis followed

by cytokinesis. In unicellular algae that reproduce sexually, each
algal cell acts as a gamete and fuses with another such gamete to
form a zygote, which then undergoes meiosis to return to haploid
state.

Multicellular algae may reproduce asexually by fragmentation, in

which each piece of a parent alga develops into a new individual,
or by motile or non-motile asexual spores.

As noted previously, in multicellular algae that reproduce sexually,

every cell in the reproductive structures of the alga becomes a
gamete-a feature that distinguishes algae from all other
photosynthetic eukaryotes.
Many multicellular algae reproduce sexually with an alteration of generations of haploid
and diploid individuals. In such life cycles, diploid individuals undergo meiosis to produce
male and female haploid spores that develop into haploid male and female thalli, which
may look identical to the diploid thallus.

In some algae, each of these thalli produces gametes that fuse to form a zygote, which
grows into a new diploid thallus. Both haploid and diploid thalli may reproduce asexually
as well.
 CLASSIFICATION OF ALGAE
The classification of algae is not yet settled. Historically, taxonomists have used
differences in:
(1) Photosynthetic pigments
(2) Storage products
(3) Cell wall composition
The 18S rRNA sequences of green algae and plants are comparable. Because of its
similarities, green algae are often considered to be progenitors of plants, and in some
taxonomic schemes the Chlorophyta are placed in the Kingdom Plantae.

Most green algae are unicellular of filamentous and live in freshwater ponds, lakes, ad
pools, where they form green to yellow scum.

Some multicellular forms grow in the marine intertidal zone-that is, in the region exposed
to air during low tide.
Chlorophyta
(Green Algae)
Prototheca is an unusual green algae in that in lacks pigments making it colorless. This
chemoheterotrophic alga causes a skin rash in sensitive individuals.
Codium is a member of a group of marine green algae that do not form cross walls after
mitosis; thus, the entire thallus is a single, large, multinucleate cell. Some Polynesians dry
and grind Codium for use as seasoning pepper.

The green algae Trebouxia is the most common alga found in association with fungi and
lichens.
Placed historically in Kingdom Plantae and then Protista, are now in their own kingdom-
Rhodophyta. They are characterized by the red accessory pigment phycoerythrin; its cell
wall is sometimes supplemented with calcium carbonate; and non-motile male gametes
called spermatia.

Phycoerythrin allows red algae to absorb short wavelength blue light and photosynthesize
at depths greater than 100 meters.

Because relative proportions of phycoerythrin and chlorophyll a vary, red algae range in
color from green to black in the intertidal zone to red in deeper water. Most red algae
are marine, though a few freshwater genera are known.
Rhodophyta
(Red Algae)
The gel-like polysaccharides agar and carrageenan, once they have been isolated from red
algae such as Gelidium and Chondrous, are used as thickening agents for the production
of solid microbiological media, and numerous consumer products, including ice cream,
toothpaste, syrup, salad dressings, and snack foods.
The brown algae are in kingdom Stramenophila based in large part on their gametes
being motile by means of two flagella-one “hairy” and one whiplike.

They have chlorophyll a and c, carotene, and brown pigments called xanthophylls.
Depending on the relative amount of their pigments, brown algae may appear dark
brown, tan, yellow-brown, greenish brown, or green.

Most brown algae are marine organisms, and some of the giant kelps, such as
Macrocyctis, rival the tallest trees in length, though not in girth.
The two types of flagella of the sperm of the brown alga, Fucus.
 Phaeophyta
(Brown Algae e.g. Macrocystis)
- The giant kelp Macrocytis, a brown alga. A kelp’s blades are kept afloat by
pneumocysts.
Chrysophyta is a group of algae that are diverse with respect to cell wall composition and
pigments. They are unified in using the polysaccharide chrysolaminarin as a storage
product. Some additionally store oils.

Modern taxonomists group these algae with brown algae and water molds in the
kingdom Stramenopila based on similarities in nucleotide sequence and flagellar structure.

Whereas some Chrysophytes lack cell walls, others have ornate external coverings such as
scales or plates.

One taxon of Chrysophytes- Diatoms, are unique in having silica cell walls composed of
two halves called frustules that fit together like a Petri dish.
Most Chrysophytes are unicellular or colonial. All chrysophytes contain more orange-
colored carotene pigment than they do chlorophyll, which accounts for the common
names of two major classes of chrysophytes-golden algae and yellow green algae.

Diatoms are major component of marine phytoplankton; free floating photosynthetic

microorganisms that form the basis of food chains in the oceans. Further, because of their
enormous number, diatoms are the major source of the world’s oxygen.

The silica frustules of diatoms contain minute holes for the exchange of gases; nutrients
and wastes with the environment.
Organic farmers used diatomaceous earth, composed of innumerable frustules of dead
diatoms, as pesticides against harmful insects and worms.

Diatomaceous earth is also used in polishing compounds, detergents, paint removers, and
as a component of firebrick, soundproofing products, swimming pool filters, and
reflective paints.
 Water Molds
Have cellulose in their cells walls while fungi have chitin.
 Water Molds

Once classified as fungi because they resemble filamentous fungi in having finely branched
filaments; however, water molds are not true molds; they are not fungi.

Water molds differ from fungi in the following ways:

(1) They have tubular cristae in their mitochondria.

(2) They have cell walls of cellulose instead of chitin.
(3) Their spores have two flagella-one whip-like and one “hairy”.
(4) They have true diploid bodies rather than haploid bodies.

Because water molds have “hairy” flagella and certain similarities in rRNA sequence to
sequence of diatoms, other chrysophytes, and brown algae, taxonomists classify all these
organisms in kingdom Stramenopila.

Water molds decompose dead animals and return nutrients to the environment. Some
species are detrimental pathogens of crops such as grapes, tobacco, and soy beans.
 Water Molds

In 1845, the water mold Phytophthora infestans was accidentally introduced into Ireland
and devastated the potato crop, causing the great famine that killed over 1 million people
and forced a greater number to immigrate to the United States and Canada.