Protistans (English Version)

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Honors Organismal Biology Laboratory113

EXERCISE 8

Protista & Fungi

The protists and fungi are extremely diverse groups of organisms that we present together in order to introduce a variety

of life cycles in addition to biodiversity. For each specimen we examine, pay close attention to the nucleus condition,

haploid (n) vs. diploid (2n); where in its life cycle does gamete production, fertilization, meiosis, and spore production

occur; and any specialized stuctures assiciated with the processes.

Kingdom Protista

The diversity of protists is so great that they posses few characteristics in common. They are eukaryotic and represent

the Þrst group to evolve intracellular structures such as the true nucleus, golgi apparatus, endoplasmic reticulum, chlo-

roplast, and mitochondrion. Moreover, ancient members of this group gave rise to the plants, animals, and fungi. Other

characteristics common to the protists are: almost all are found aquatic or semi-aquatic environments, most require aer-

obic conditions, most possess ßagella or cilia at some point in their life history, many are unicellular, and most are capa-

ble of producing cysts at some point in their life cycle that are resistant to drought of freezing.

Phyllogenetic relationships among many members of this Kingdom are uncertain and the subject of much debate. At

present, inclusion in the Kingdom Protista is a matter of convenience rather than representing distinct evolutionary

lines. However, protists can be grouped into three basic catagories based on morphological and life cycle traits: the pro-

tozoans, algae, and fungus-like protists. It is important to note, however, there is no clear distinction among these

groups. As an example, many ßagellated protozoans are closely related to the algae and even members of the samegenus have both colorless and chloroplast-containing members.

Protozoa

The name ÒprotozoaÓ means ÒÞrst animalsÓ, attributed because most orgamisms of this group engulf their food.

TABLE 52. Summary of characteristics and examples of protozoan phyla.

Phylum Characteristcs Examples

Rhizopoda possess pseudopods (false feet); lack

meisois and sexual reproduction; naked

or have shells; unicellular

Ameoba

, Entamoeba histolytica

(causes

amoebic dysentery) Entamoeba coli

( a

common gut commensal); Difßugia

Actinopoda possess axopodia; usually have silica

skeletons and spines; unicellular

heliozoans (mostly freshwater) and

radiolarians (mostly marine)

Foraminifera possess a calcareous shell; many with

commensal algae; unicellular

Apicomplexa (= Sporozoa) mostly parasitic; complex life cycle;

unicellular

Plasmodium

(causes malaria)



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Algal Protists

These are the eukaryotic algae, which form the base of the food chain for most aquatic habitats.

Zoomastigina possess ßagella; unicellular or colonial

Trypanosoma

(causes African Sleeping

Sickness, ChagasÕ disease), Trichomo-

nas vaginalis

; Giardia

; ßagellates of termite guts

Ciliophora possess cilia for locomotion and feed-

ing; unicellular or colonial

Stentor, Paramecium

, Vorticella

;

rumen ciliates

TABLE 53. Character summary and examples of the major algal divisions.

Division (=Phylum) Pigments Cell Wall

FoodStore Flagella Body form Other Examples

Chrysophyta

(Golden

Algae)

chl a, chl c ,

b

carotene

lorica of sil-

ica & cellu-

lose

lipids &

lami-

narin

2; unequal

length

unicellular,

colonial

Fall dom-

inant

Dinobryon

,

Mallomonas

Bacillario-

phyta (Dia-

toms)

chl a, chl c ,

b

carotene

silica oils &

leucosin

none;

gametes Ð 2

unequal

unicellular,

Þlamen-

tous, colo-

nial

high

diversity

centrics &

pennates

Euglenophyta chl a, chl c ,

b

carotene

reinforced

pellicle

paramy-

lon

2(1,3) unicellular stigma;

some col-

orless

Euglena

,

Phacus

Pyrrophyta

(dinoßagel-

lates)

chl a, chl c ,

b

carotene

internal cel-

lulose plates

starch 2 unequal,

in grooves

unicellular red tides

Ceratium

,

Gymnodiniun

Rhodophyta

(Red Algae)

chl a, bilip-

roteins, a

&

b

carotene

ÔagarÕ a glycan none unicellular,

Þlamen-

tous, thal-

lus

deep

tropical

marine

Batrachosper-

mum

, Rhody-

menia

.,

Polysiphonia

Phaeophyta

(Brown Algae)

chl a, chl c,

b

carotene

cellulose,

other

polysaccha-

rides

lami-

narin

none;

gametes Ð 2

unequal

thallus cold

marine

Laminaria

,

Fucus

, Sargas-

sum

Chlorophyta

(Green Algae)

chl a, chl b,

b

carotene

cellulose starch 0,2,4,many;

equal

unicellular,

Þlamen-

tous, colo-

nial

mostly

freshwa-

ter

Chlamydomo-

nas

, Volvox

,

desmids, Spir-

ogyra

TABLE 52. Summary of characteristics and examples of protozoan phyla.

Phylum Characteristcs Examples



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Kingdom Fungi

Fungus-like Protists

The slime molds and water molds resemble true fungi but they are not closely related to them. Slime molds are decom-

posers of rotten logs and leaf litter in forested ecosystems, while water molds decompose algae, leaves, and dead animals

in aquatic ecosystems. Some water molds are parasitic and grow on the skin of Þsh and amphibians or on plants.

Kingdom Fungi

The fungi are important decomposers of terrestrial environments as well as parasites of plants and animals. The basic

structure of multicellular fungi includes a thread-like net of hyphae

(each thread), which collectively is called mycelium

.

Hyphae of most fungi have cross walls, called septae

, that divide the thread into cells. Other fungal hyphae are coeno-

cytic

, i.e., they lack cross walls.

Lichens

Lichens are an integrated symbiotic relationship between a fungus, usually an ascomycete, and a green or blue-green alga.

They can live in some of the most inhospitable habitats because each supplies what the other canÕt obtain on its own. The

fungus-part may supply moisture and nutrients, while the algae-part supplies the food source via photosynthesis.

TABLE 54. Summary of characteristics and examples of fungus-like protists.

Phylum Characteristics Examples

Myxomycota (Plasmodial

Slime Molds)

ceonocytic, plasmodial feeding stage;

reproductive stage forms sporangia

Physarum

, Stemonitus

Acrasiomycota (Cellular

Slime Molds)

solitary cells in feeding stage; repro-

ductive aggregate forms sporangia

Dictyostelium

Oomycota (Water Molds) hyphae have cellulose cell walls; dip-

loid condition dominates

Phytophthora

(causes potato blight),

ÔIckÕ infection on Þsh

TABLE 55. Summary of characteristics and examples of true fungi.

Division Characteritics Examples

Zygomycota asexual spores on sporangia; sexual spores:zygospores

Rhizopus

Ascomycota asexual spores: conidia; sexual spores Ð 8 ascospores

in ascus; fruiting body: ascocarp

Morchella, yeast

Basidiomycota sexual spores: basidiospores on basidium; friuting

body: basidiocarp

Agaricus

, toadstools, shelf

mushrooms

Deuteromycota no sexual reproduction

Penicillium



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Exercises

1.

Examine the Mixed Protozoa culture under a compound microscope. Search for rhizopds such as Amoeba

; ciliates

such as Paramecium

, Vorticella

, or Stentor

; and ßagellates. Sketch and label your observations below:

2.

Examine the prepared slide of Actinosphaerium

, an actinopod. Sketch the organism and label the axopodia.

3.

Examine the prepared slide of Trypanosoma lewisi

, a parasitic ßagellate of rats. Sketch the ßagellate and a few blood

cells. How big are red blood cells and the trypanosome?




117

Exercises

4.

View the demonstration of of termite gut ßagellates and rumen ciliates. Sketch two kinds of ßagellates and ciliate

from each sample.

5.

Examine the living culture of Mixed Diatoms and Desmids. Diatoms are bacillariophytes and can be recognized by

their golden chloroplasts and glass cell walls; whereas desmids are chlorophytes and have bright green chloroplasts.

Each desmid is composed of two semi-cells conjoined at the center. Can you differentiate the two types of algae?

Sketch and label one or two individuals of each type.

6.

Ask the TA to demonstrate a prepared slide of diatoms. Sketch several pennate and centric diatoms.

7.

View the specimen of Ceratium

, a dinoßagellate, on demonstration. Sketch and label the cell wall, grooves, and ßagel-

lae.



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8.

Observe cultures of Chlamydomonas

and Volvox

. Also obtain a prepared slide of Volvox

sexual stages and note the

zygotes. Sketch your observations and label the chloroplast, mother and daughter colonies,

9.

Ask the TA to demonstrate various algae and protozoans in a pond water sample. (You may wish to observe the pond

water sample on your own too.) Be able to identfy the specimens to division and phylum levels. Sketch a few of the

organisms you Þnd.

10.

View the live specimens of Rhodophyta: Batrachospermum

, cold-water stream, Þlamentous algae, and Rhodymenia

, a

tropical marine thallus. Sketch your observations.

11.

View the specimens of marine Phaeophyta on demonstration: Laminaria

(a kelp), Fucus

(rockweed), and Sargassum

(gulfweed). Identify holdfasts, ßoats, blades, and reproductive structures.

12.

View cultures of Physarium

, a myxomycete, under a stereo microscope. Note plasmic streaming of the plasmodium

and the fruiting structures.




119

Exercises

13.

Observe the moldy bread (

Rhizopus

) on display under the stereo microscope. Note the mycelium, sporangia, and spo-

rangiophores. Place a small amount of the Rhizopus

culture on a slide and sketch and label your observations. See also

prepared slides of Rhizopus

conjugation and note the zygospore.

14.

Observe the Morchella

, an ascomycete, on demonstration. Obtain a prepared slide of a Morchella

cross-section and

sketch and label the mycelium, asci, and ascospores of the ascocarp.

15.

Observe various specimens of basidiomycetes on demonstration. Obtain a prepared slide of a Coprinus

section and

sketch and label the mycelium, basidia and basidiospores of the basidiocarp.

16.

Observe the various lichen specimens on display. Obtain a prepared slide of a lichen section. Note the algal layer.



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Protistans (English Version)