Lab Practical 4: Survey of Protists

How does the structure of tissue surrounding the reproductive structures compare with that of green algae?

Tissues in brown algae are more complex

filamentous green algae: Spirogyra

grows in running streams of cool fresh water and secretes mucilage that makes it feel slippery -reproduces sexually by conjugation

Are spores of Chlamydomonas haploid or diploid?

haploid

fungi

have cell walls and are heterotrophic -heterotrophic organisms feed on organic matter produced by other organisms

protists

include all eukaryotes that lack the distinguishing characteristics of fungi, animals, or plants -live in moist habitats and include simple eukaryotes such as amoebas as well as multicellular organisms such as brown alga, microscopic

Supergroup Amoebozoans

includes amoeboids, plasmodial and cellular slime molds -pseudopods, unicellular

Supergroup Opisthokonts

includes choanoflagellates, animals, nucleariids, fungi -some with flagella, unicellular and colonial

Supergroup Excavates

includes euglenoids, kinetoplastids, parabasalids, diplomonads -feeding groove, unique flagella, unicellular

Supergroup Rhizarians

includes foraminiferans, radiolarians -thin pseudopods, some with tests, unicellular

Supergroup Archaeplastids

includes green algae, red algae, land plants, charophytes -plastids, unicellular, colonial, and multicellular

euglenoids (Euglenida)

includes mostly freshwater unicellular algae -plastids contain chlorophyll a and b (like green algae) -lack cell wall, have pellicle made of protein to be more flexible -motile and have two flagella -chloroplasts may contain single pyrenoid (appears as clear, circular area within plastid) -can be autotrophic, heterotrophic, or saprophytic (dead or decaying matter)

Supergroup Chromalveolates

includes stramenopiles (brown algae, diatoms, golden algae, water molds) and alveolates (ciliates, apicomplexans, dinoflagellates) -most with plastids, unicellular and multicellular -alveoli support plasma membrane, unicellular

animals

ingestive feeding heterotrophs that are multicellular, lack cell walls, and can respond rapidly to external stimuli

Brown algae contain chlorophyll. Why, then, do they appear brown and not green?

it also has the pigment fucoxanthin responsible for it's brown color

What is the function of the eyespot (stigma) of Euglena?

light reception

unicellular green algae: Chlamydomonas

motile, unicellular alga found in soil, lakes, and ditches -simplest structure and type of reproduction among green algae -egg shaped cells contain a large chloroplast and a pyrenoid involved in the production and storage of starch

plants

multicellular, autotrophic organisms that synthesize all required organic compounds from inorganic substances using external energy usually sunlight

Are filaments of Spirogyra branched?

no

Can you see any pores in the walls of diatoms?

no

red algae (Rhodophyta)

obtain their color from the presence of red phycobilins in their plastids -typically live in warm marine waters -thallus can be attached or free floating, filamentous, or fleshy

domain Eukarya

organisms composed of cells having membrane bound nuclei -kingdoms Fungi, Animalia, Plantae, and protists

Describe three ways that algae affect your life.

oxygen production, food, and pharmaceuticals

How do you suppose they get out?

parent colonies disintegrate

algae

photosynthetic, eukaryotic organisms typically lacking multicellular sex organs -often grouped by colors of pigment (substances that absorb light) or by their cellular organization (unicellular, filamentous, or colonial)

conjugation

-filaments of opposite mating types lie side by side and form projections that grow toward each other -projections touch and separating wall dissolves thus forming a conjugation tube -cellular contents of - strain migrate through tube and fuse with that of nonmotile + strain -cellular contents of these two strains function as non flagellated isogametes -zygote results from fusion of gametes develops into zygospore -zygospore is released when filament disintegrates, undergoes meiosis to form haploid cells that become new filaments

alternation of generations

-haploid gametophyte produces gametes that fuse to form a zygote -zygote germinates to produce diploid sporophyte -meiosis produces spores that germinate into gametophytes

sexual reproduction in Fucus

-immature antheridium and immature oogonium undergo meiosis -mitosis and sperm formation, mitosis and egg formation -gametes fuse (syngamy) to form a zygote -zygote germinates

Chlamydomonas life cycle

-individual cells are haploid and divide asexually via mitosis -haploid cells act as gametes and fuse to produce a diploid zygote (syngamy=pairing and fusion of morphologically similar haploid gametes) -zygote becomes zygospore -meiosis produces four haploid individual spores under favorable conditions -spores develop into adult without fusing

oogamy

-motile sperm swim to and fuse with the large nonmotile eggs to form a diploid zygote -zygote enlarges and develops into zygospore, released when parent colony disintegrates -zygospore undergoes meiosis to produce haploid cells that subsequently undergo mitosis and become a new colony

What is meant by the term "kelp"?

A large brown seaweed algae/laminaria

Which portions of the life cycle of Chlamydomonas are haploid?

All portions from meiosis to syngamy (haploid spores and haploid individual cells)

What are examples of unicellular, filamentous, and colonial green algae?

Chlamydomonas are an example of unicellular green algae. Spirogyra are filamentous and Volvox is colonial

How are green algae different from cyanobacteria?

Cyanobacteria are prokaryotic and algae is considered eukaryotic. Cyanobacteria do not have membrane-surrounded nucleus

Are the swollen structures solid masses or are they hollow?

Essentially empty.

How does the structure of Fucus differ from the green algae that you examined earlier in this exercise?

Fucus is larger, more parenchymatous, and flattened

How do you think the number of cells in a young Volvox colony compares to the number in a mature colony?

Less than or equal to the number in the mature colony

How do you think Spirogyra reproduces asexually?

Mitosis and fragmentation

Are the gametes of Fucus isogamous or oogamous?

Oogamous because it involves male and female parts

Are all portions of the thallus photosynthetic? How can you tell?

Probably not, due to different concentrations of pigments.

Are any of the diatoms moving?

yes

Considering where Fucus lives, what do you think is the function of its gelatinous sheath?

Since Fucus lives in intertidal regions, the gelatinous sheath probably prevents desiccation

Can you see any conjugation tubes?

yes on prepared material

Which are diploid?

zygote and zygospore

What are the main differences and similarities among the major groups of algae? How are these groups related to each other evolutionarily?

The major groups of eukaryotic algae are the green algae, diatoms, red algae, brown algae, and dinoflagellates. They are classified as protista. All are eukaryotic and lack distinguishing characteristics of fungi, plants, and animals. Some are unicellular, colonial, multicellular, autotrophic, or heterotrophic. Most of them are microscopic in size and live in moist habitats. Show evolutionary relatedness with fungi, plants, and animals, but don't form a monophyletic group descended from a single common ancestor.

How is Cladophora morphologically similar to Spirogyra? How is it different?

They are both filaments, but Cladophora is branched and Spirogyra is unbranched.

Why are green algae considered to be ancestral to plants?

They are considered to be ancestral to plants because they both reproduce chlorophyll a/b and both have cell walls made of cellulose

Are the stem, holdfast, and blade of brown algae the same as stems, roots, and leaves of land plants? Why or why not?

Yes, because they serve the same type of functions. The blade of algae like the leaves of plants is where photosynthesis takes place, the holdfast is like the stem of a plant because it holds together the organism.

green algae

ancestral to land plants and share many characteristics such as -chlorophyll a -chlorophyll b -starch as the carbohydrate storage material -cell walls made of cellulose

filamentous green algae: Cladophora

common in streams and much more coarse in appearance and texture -exists in diploid and haploid forms, alternation of generations reproductive cycle

colonial green algae: Volvox

consists of many Chlamydomonas-like cells bound in a common spherical matrix -each cell in the sphere has two flagella extending outward from the surface of the colony -synchronized beating of flagella spins colony through water like a globe on its axis -reproduces by oogamy -in asexual reproduction some cells divide, bulge inward, and produce new daughter colonies that initially are held within parent colony

What are the tiny spheres inside the larger sphere of Volvox?

daughter colonies

How does the stigma (eye spot) help Chlamydomonas survive?

detects light

How would diatomaceous earth compare to sand as a material for swimming pool filters? Which would be better and why?

diatomaceous earth because its finer and smaller

How do the shapes of dinoflagellates compare with other unicellular algae that you have observed in this exercise?

different in shape, cellulose plates

Is the movement of Chlamydomonas smooth or does it appear jerky? Can you see both flagella?

relatively smooth, probably not

brown algae: Fucus (female conceptacle)

rockweed, typically attaches to rocks in the intertidal zone via a holdfast -outer surface covered by a gelatinous sheath -tips of branches called conceptacles, may be swollen and contain multicellular reproductive structures called oogonia (female) and antheridia (male) -mature thallus (plant body without stem, leaves, roots, vascular system) is diploid and cells within reproductive structures undergo meiosis to produces gametes (skips haploid stage)

If diatoms lack flagella, how do you explain their motility?

silicon gel that is used to help them move

How does methyl cellulose affect the movement of Chlamydomonas?

slows it down

What is the arrangements of chloroplasts of Spirogyra?

spiral

Spirogyra conjugation tube

top - strain, bottom + strain, tube connects strains

Under what environmental conditions would a zygote not undergo meiosis immediately?

unfavorable conditions

diatoms (Bacillariophyta)

unicellular algae containing chlorophyll a and c and xanthophyll pigments that give them their golden brown color -tiny, photosynthetic, rapid rates of reproduction -hard cell all made of silicon dioxide (glass) -walls arranged in overlapping halves, persist long after the remainder of the cell disintegrates and may accumulate in layers of diatomaceous earth several hundred meters deep -always symmetrical, always glass shells

dinoflagellates (Dinozoa)

unicellular, characterized by appearance of cellulose plates and presence of two flagella located in perpendicular grooves -important primary producers in oceans (second to diatoms) and include many heterotrophic and autotrophic forms -some are bioluminescent, heterotrophic, or symbionts with corals

economic importance of brown algae (Phaeophyta)

used as food and alginic acid (hydrophilic substance that absorbs large quantities of water) which is used in dripless paint, ice cream, pudding mixes, and cosmetics

brown algae

usually grow in cool water and obtain their name from the presence of a brown pigment called fucoxanthin -range in size from microscopic forms to kelps over 50m long