Name: ____________________

ProtistsRevised: Spring 2012

Contents:

Introduction................................................................................................................146Ecological Importance of Protists..............................................................................147Exercise 1: Protozoa.................................................................................................148

Ciliated Protozoa............................................................................................148Paramecium.......................................................................................148Stentor................................................................................................150

Amoeboid Protozoa.......................................................................................151Exercise 2: Algae......................................................................................................152

Green Algae...................................................................................................153Chlamydomonas.................................................................................153Volvox................................................................................................154Spirogyra............................................................................................154Ulva....................................................................................................155

Diatoms..........................................................................................................155Dinoflagellates...............................................................................................156Brown Algae..................................................................................................157Red Algae.......................................................................................................157Euglenoid Algae.............................................................................................158

Exercise 3: End of Lab Questions.............................................................................159Exercise 4: Protist Review Worksheet......................................................................160

ProtistINTRODUCTION

Protists are eukaryotes, but beyond that, they are difficult to classify. The group of organisms that fit into the “protist” category has more than 7 kingdoms and 10,000 species. About the only thing they all have truly in common is that they are all eukaryotes. They also are all similar in having a less complex organismal organization than the fungus, plants, or animals. To make more sense of this catch-all group, it is divided into three major groups. These groups are:

1. The protozoa - single celled animal-like protists.2. The algae - plant-like protists.3. Slime molds - fungus-like protists.

Note that these are also informal group names, like “protist,” and not official classification taxa. You already studied protists a bit during the Diversity Lab at the start of this semester. You will continue to study protists here and learn about some of the formal Kingdom and Phylum names that may (or may not) remain in place. However, in this lab, we will restrict our further study to the protozoa and algae, and we will not be viewing examples of slime molds.

Why is it that we have so much trouble classifying these organisms? You tried to classify many of them during the Diversity Lab, but may remember that it wasn’t easy. The quick answer as to why it is so difficult is because we have only recently developed the appropriate methods to classify them properly! You see, years ago, people came up with a classification scheme based on readily observable organizational features. Before the 1900s, we classified all living things as either plant or animal. Then we observed fungus more closely and realized that they were too different from plants to be grouped with them. As our microscopes improved, we learned about microscopically-small organisms, and tackled grouping them as well; this was when the name “protists” arose. By the mid-1900s, we had learned that there were different types of cells, and by the later 1900s we determined that there were different kinds of prokaryotic organisms (thus, Domain Archaea and Domain Bacteria were named). However, observable organismal characteristics are not the only ones we can now use. We can now directly compare the DNA from different organisms to decipher their relatedness. The more similar the genetic code between two species, the more closely related they are.

It turns out that not all organisms that look similar are closely related! You can probably relate to this notion if you think about the fact that while some human siblings look similar, others don’t look at all alike—and yet they are still siblings and very closely related. It is the genetic code of the organisms that provides the key to understanding how related different organisms truly are. We have only learned how to obtain the genetic code of organisms quickly and easily in the last 15 years with the international effort made on the Human Genome Project. Therefore, now we have a lot of new data to look at and re-evaluate organismal relatedness. This new information is going to help us shape our taxonomic classification, and make it more accurate. Until that time when we know exactly how many kingdoms lie within the informal grouping called the protists, we will have to just do our best to try to understand these organisms.

Ecological Importance of Protists

While responsible for causing many dreaded human diseases (malaria, sleeping sickness, and giardiasis to list a few), protozoa also benefit humans tremendously. Protozoa are important nutrient recyclers in natural ecosystems. Without organisms like bacteria, fungi and protozoa, soils would quickly become depleted of nutrients making plant growth impossible. All organisms on earth depend on healthy plant populations for survival. Protozoa also play a key role in wastewater treatment plants by consuming enormous quantities of bacteria, and are important components of food chains.

Algae is much more than simply "seaweed" or "pond scum"--it is a vital component of our biosphere, and the survival of humans would be jeopardized without it. We often hear of the rain forests as being important in making oxygen, and they are important in many ways, but most of the oxygen we actually breathe is made by algae in the ocean. Indeed, algae produced more than 50% of the oxygen molecules that your cells consumed during this laboratory! Algae also form the base of aquatic food chains. This algae is primarily microscopic, and is called phytoplankton. Without algae in lakes, rivers, and oceans, there could be no life in these environments since all aquatic life either directly feeds on algae, or feeds on organisms that feed on algae. Humans usually eat from the top of the food pyramid. Without phytoplankton in the oceans, salmon, tuna, cod, shrimp, lobsters and a myriad of other seafood products would not be available to us.

An Aquatic Food Chain

Exercise 1: The Protozoa

Protozoa are single-celled, heterotrophic organisms. Although most are single celled, that one cell is still able to carry out all the functions necessary for life: ingesting and digesting food, expelling waste, and obtaining oxygen.

Protozoa live just about anywhere that is moist, on both land and sea, but in this lab we will primarily be looking at protozoa that live in fresh water environments.

Protozoa that live in fresh water face a problem; compared to the surrounding water the high concentration of solute in their cells creates an osmotic gradient. Which way do you think the water moves in this gradient? Protozoa respond to this problem with a contractile vacuole. The contractile vacuole is a cellular structure that constantly pumps water out of the cell.

There are so many different protozoa, it’s not easy to divide them up into species. The current approach is for taxonomists to classify protozoa according to their method of movement, and it is the mode of locomotion on which we will base our study of the protists today.

Ciliated Protozoa

Ciliates are protozoa that move and obtain food by means of short, hair-like structures called cilia. It is thought that they fit into Kingdom Alveolata. A cilium (singular) extends from the cell membrane and is composed of bundles of microtubules. In most ciliates, cilia cover the entire cell surface. Protozoa use their cilia for two purposes:

1. Locomotion2. Feeding. The cilia sweep smaller protists, bacteria, and non-living organic matter into an oral

groove on the cell surface. At the far end of the oral groove, a food vacuole forms. Ciliates occupy a variety of habitats including freshwater, soil and as symbiotes in the guts of invertebrates.

Study of Paramecium – Watch the video of the paramecium.

Questions about Paramecium.

Do the cilia beat in a synchronized pattern, or does each just beat on its own? ________________

Explain why Paramecium’s body spirals as it moves through the water?

Contractile vacuole in a paramecium. Note the array of channels that carry water

to the central vacuole.

0

1

2

3

4

5

6

1 2 3 4

Saltiness of pond water.

Contractions per minute.

0

1

2

3

4

5

6

1 2 3 4

Contractions per minute.

Saltiness of pond water.

Graph A Graph B

Less saltyLess salty

More saltyMore salty

Circle the correct graph.

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Look for contractile vacuoles within each cell. What collects within the contractile vacuoles of the cell?

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Why are contractile vacuoles are needed by these organisms (hint: think in terms of osmotic gradients)?

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Please explain what might happen to Paramecium if the contractile vacuoles stopped functioning?

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The following two graphs show how many times Paramecium’s vacuole might contract in pond waters of varying saltiness. One graph is correct and the other is not. Circle the correct graph. Explain your choice on the next page.

Did you circle Graph A or Graph B on the previous page? ______________________________

Please explain your choice. _____________________________________________________________

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Stentor

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Sketch a Paramecium in the space below the way it looks to you using the prepared slide. Label your sketch.

Study of Stentor: Watch the video of the stentor Answer the questions below. Food vacuoles should be

apparent in these organisms.

Are the cilia the same all over the cell, or are they more

dense in some areas. Explain.

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Sketch a Stentor in the space below the way it looks to you. Label your sketch.

Amoeboid Protozoa

Amoeboid protozoa are a large group that includes the amoebas. Amoebas move using pseudopodia. Pseudopodia are protoplasmic extensions that pull the organism in a particular direction. Amoebas also use these "false feet" to capture food through a type of endocytosis known as phagocytosis. Most freshwater environments include harmless species of amoeba, and it is one of these we will be observing today. In

addition to slow moving streams and ponds, Amoeba species also inhabit soil and saltwater and a few even live as parasites in the digestive systems of humans and other animals.

Study of Amoeba – Watch the video of the amoeba.

Note the irregular shape, the slow movement (streaming) of the protoplasm, and the formation of pseudopodia.

List 2 functions of pseudopodia __________________________________________________________

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Do you see any food vacuoles? If so, describe their appearance. ______________________

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Do you think it is likely that amoeba require contractile vacuoles? Please explain your answer.

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Sketch an Amoeba in the space below the way it looks to you from the prepared slide. Label your sketch.

Exercise 2: The Algae

Algae are autotrophic (photosynthetic) organisms. Like the protozoa, some algae are single-celled. Unlike the protozoa however, many algae are multicellular and may be quite large. Most algae live in water, but

they may also be found in any place that is moist at least part of the time. Algae are around us all the time and can be found on shady brick walls, the fur of some mammals, in swimming pools, birdbaths, flowerpots, and gutters on the roof.

Over 30,000 species of algae have been described by Phycologists (Phycology is the study of algae). Like the protozoa, taxonomists need a way to divide up all these species. The way they do it is by color and by how complicated the algae is.

Divisions of algae by color.Different species of algae use different types and mixes of chlorophyll and this leads to their being different colors. Based on color, there are four main groups of algae. They are:

A. Green algaeB. Brown algaeC. Golden-brown algaeD. Red algae

Look at the seaweed the next time you’re at the beach. The four colors are usually pretty easy to find.

Divisions of algae by complexity.In addition to being different colors, some algae are more complex than others. Algae can be divided into the following four categories based on the complexity of the organism:

A. Unicellular algae Consist of only one cell living on its own.B. Colonial algae Consists of a colony or

cluster of more or less identical cells. Each cell could live on its own, but they choose to live together.

C. Filamentous algae Consists of a long chain of more or less identical cells. Again, each cell could live on its own, but they choose to live together.

D. Multicellular algae These are diverse, since they may be very simple (where all the cells look similar) or they may be more complex (and have specialized cells). Large seaweed, for example, has special cells that form root-like holdfasts to hold on to rocks.

Question: Which of these products contains algae?

Answer: They all do!

Groupings of algae by genetic comparisons into KingdomsA. Kingdom Euglenozoa These algae are motile (using flagella) and can either eat like a

protozoan or carry out photosynthesis.B. Kingdom Stramenopila This group contains the brown algae, the diatoms and other

groups.C. Kingdom Rhodophyta This group contains the red algae.D. Kingdom Alveolata Although we saw this kingdom back in the protozoa section as the

group that contains ciliates, it also contains the dinoflagellates.E. No Green Algae! The green algae have been temporarily re-assigned into the

Kingdom Plantae as Division Chlorophyta. These organisms may stay in with the plants, or may return to the group of protists as their own kingdom.

Green Algae

Chlamydomonas

Chlamydomonas is algae, but it has an eyespot to detect light and flagella to swim toward the light. It’s a good example of how it is hard to fit protists into categories. Each cell also has a granule of stored starch and two flagella.

Watch the video of the Chlamydomonas. . Note their small size. Identify flagella and the starch granule if possible.

To which of the 4 color categories does Chlamydomonas belong? __________________________

To which of the 4 complexity categories does Chlamydomonas belong? __________________________

Volvox

Each of the cells in Volvox also has a flagella. Flagella are beat by individual cells in synchrony with other cells. This allows the whole Volvox to move through the water in an orderly manner.

Observe the Volvox using the prepared slide. Note the daughter (reproductive) colonies that may be seen inside some Volvox.

To which of the 4 color categories does Volvox belong? __________________________

To which of the 4 complexity categories does Volvox belong? __________________________

Sketch a Volvox in the space below the way it looks to you. Label your sketch.

Spirogyra

Spirogyra is what we may think of as "pond scum", since it forms thick mats on the surface of ponds when conditions are right. Spirogyra takes the form of thread-like strands called filaments. Each filament is composed of many cells linked end to end. Spirogyra gets its name from the fact that the chloroplasts inside the cells are arranged in distinctive spirals.

Using the prepared slide. Note the characteristic spiral-shaped chloroplasts. Look for a nucleus within each cell of the filament. The nucleus is suspended in strands of cytoplasm, much like a spider might be found sitting in the center of a web.

Note the filamentous shape of the algae. Are the filaments branched? _________________

Can you see cell walls separating the individual cells of the filament? _________________

To which of the 4 color categories does Spirogyra belong? __________________________

To which of the 4 complexity categories does Spirogyra belong? __________________________

Sketch Spirogyra below and label any visible feature, vegetative filaments and lateral conjugation (2 slides).

Volvox

Spirogyra

Ulva

An abundant marine species of algae is "sea lettuce" or Ulva. The body or thallus of Ulva includes a tiny root-like holdfast that anchors the algae onto rocks or other substrate on which it is growing. The thallus of Ulva is only several cell layers thick.

Go to the Ulva website.

To which of the 4 color categories does Ulva belong? __________________________

To which of the 4 complexity categories does Ulva belong? __________________________

Diatoms

Diatoms usually have very small cells and are found in abundance in both terrestrial, marine, and freshwater environments. The defining characteristic of diatoms is the presence of their glass-like cell walls or frustules composed of silica. The walls are arranged in overlapping halves, much like a candy box or petri dish fits together.

Once the organism dies, the cell inside decomposes but the glass-like frustule remains intact for hundreds or thousands of years. Over thousands of years significant deposits of frustules may accumulate on the ocean floor. These deposits may then be mined to provide diatomaceous earth. Humans use this material in a wide array of products, including paints, cement, fertilizers, toothpaste, polishes, and cleaners. Diatomaceous earth also kills snails and slugs. Examine the diatomaceous earth on display in lab.

Watch the diatoms video.

Note the many shapes. To which of the 4 complexity categories do Diatoms belong? ________________

Sketch a few diatoms below, in the area between the photos of diatoms:

Electron microscope picture of a diatom's frustule. An incredibly complex shell for a creature that is only one cell!

To which of the 4 color categories do Diatoms belong?

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To which of the 4 complexity categories do Diatoms belong? ________________

Dinoflagellates

Dinoflagellates are unicellular algae that move with two flagella. Because of the positioning of their flagella, they tend to whirl about in the water. The prefix “dino-” means whirling, so they are named according to the way they move. Although dinoflagellates move, they are also autotrophic. They are also algae because they have very interesting cell walls made up of many plates like armor. Their two flagella have to stick out through grooves in their cell plates.

Observe the living specimens of Peridinium through video

To which of the 4 complexity categories does Peridinium

belong? __________________________

Brown Algae

Laminaria and Fucus are types of kelp. Kelps are typically dark brown in color and are only found in marine environments. They generally prefer cooler oceans over warm. Each individual kelp is composed of a basal holdfast, which anchors the organism, blades which look and act like leaves, and a stalk-like stipe. Keep in mind though, that kelp are not plants because they lack true stems, leaves and roots. Distributed along the blade may be several or many air bladders that help to keep the blade buoyant.

A thick growth of kelp can create an underwater forest along many temperate shores. Kelp forest are extremely important ecologically because they create an environment where marine mammals, fish, and invertebrates can hide, raise their young, and seek protection from storms.

Use the website to learn more . Make a sketch in the space below. Include and label on your sketch: Holdfast, blade, and stipe. If time

allows, make a wet mount of a small section of the blade, and draw the cells you see below as well.

To which of the 4 color categories does kelp belong? __________________________

To which of the 4 complexity categories does kelp belong? __________________________

Red Algae

Batrachospermum, genus of freshwater red algae ranging in colour from violet to blue-green. The long, branched, threadlike filaments bear dense whorls of branchlets, resembling beads on a string. Spores are formed in clusters around the base of the carpogonium (female sex organ) after fertilization. The genus is found in streams and in pools in sphagnum bogs.

Observe Batrachospermum using the prepared slide.

Note the filamentous shape of the algae. Are the filaments branched? _________________

Can you see cell walls separating the individual cells of the filament? _________________

To which of the 4 color categories does Batrachospermum belong? __________________________

To which of the 4 complexity categories does Batrachospermum belong?__________________________

Sketch Batrachospermum in the space below the way it looks to you. Label your sketch.

Euglenoid Algae

Study of Euglena - Euglena are freshwater protists that exhibit characteristics of both protozoa and algae. Algal characteristics include the ability to photosynthesize and store starch. Protozoan characteristics include the lack of a cell wall, and the ability to ingest food. Some species of Euglena are very tolerant of polluted waters, and act as water quality indicators for humans when expensive pollution monitoring equipment is not available.

Watch the video of the Euglena. Look for the red stigma or “eyespot” near the flagellum. This structure allows the organism to sense

different light intensities. Note the very flexible external membrane or pellicle, as well as green coloration of the organism that indicates the presence of chloroplasts.

Why is a structure such as the stigma important for photosynthetic organisms like the Euglena?

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Do you think Euglena require contractile vacuoles? Explain. _______________________

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Chlamydomonas is a lot like Euglena in many ways. There is another organism we have seen today that also shares some similarity to Euglena. What other organism has traits in common with Euglena and what are the traits?

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To which of the 4 complexity categories does Euglena belong? __________________________

Note that you were not asked to put Euglena into a color category… that is because this organism is NOT

a green algae, but is in a different phylum, the Euglenoids.

Sketch a Euglena from the prepared slide in the space below the way it looks to you. Label your sketch.

Mixed Protozoa – View the slide mixed protozoa. Sketch at least 5 protozoa. Identify each sketch using resources provided by teacher.

Exercise 3: End of Lab Questions

You may have to consult other sources of information to correctly answer some questions.

1. Approximately 100,000 species of protists have been identified and classified. Most taxonomists, however, believe that this number is low and that many thousands more await discovery by humans. Explain why you think it is so hard to find new species of protists.

2. List functions of the following: Pseudopodia, flagella, chloroplast, stigma, holdfast, cilia, food vacuole, contractile vacuole.

3. Suppose that as the result of extensive pollution to the ocean, kelp forests are killed. Explain how this would affect not only kelp populations, but also many other forms of marine life.

4. Why are protozoa not classified into the animal kingdom? List 2 reasons.

5. Why are algae not classified into the plant kingdom? List 2 reasons.

6. What is agar? Carrageenan? Algin?

7. List 3 ways an amoeba is similar to a human.

8. List 3 ways humans and Paramecium differ.

9. Protozoa are: Heterotrophic or Autotrophic? Define your answer.

10. On your first day on the job as Naturalist at Cape Cod National Seashore, an angry visitor approaches you complaining about all the "good fer nuthin seaweed" littering the beach. In a paragraph, explain to the visitor 5 ways humans benefit from algae.

11. If both protozoa and most bacteria are single-celled and heterotrophic, why are they classified into separate kingdoms? Explain.

12. Paramecium possesses unique organelles called trichocysts. See if you can find out what these are and their function.

13. Suppose that as a result of a genetic mutation a particular freshwater protozoan loses the use of its contractile vacuole. Is this organism likely to survive, reproduce, and pass this characteristic on to its offspring? Explain.

Exercise 4: Protist Review Worksheet

protistsProtozoa Algae

Ciliates

Flagellates

Green A

lgae

Red A

lgae

Diatom

s

Euglenoids

Dinoflagellate

Brow

n Algae

Uni-cellula

r

Uni-cellular

Uni-cellula

rno

example given

Uni-cellula

r

Colonial Fila-mentous

Multi-cellular

Multi-cellular

Multi-cellula

r

Uni-cellular

Uni-cellula

r

Uni-cellular

Multi-cellular

Organisms you may have seen today: Put each organism you saw into an organism box above to organize all that you viewed!

Spirogyra Chlamydomonas Euglena Stentor Chondus Crispus

Amoeba Fucus or Laminaria Paramecium Batrachospermum Volvox

Ulva Diatoms Peridinium

Grouping

Am

oebas

Organi

sm

protists: 161

protists: 162