Name: ____________________________________________________________
Any organism that belongs to Kingdom Protista belongs to an immensely diverse group of organisms that do not really fall into any category and are constantly being reclassified into groups. Recent studies of protist DNA and structure has shown that the protists are far more diverse than had been previously expected. In fact, since this lab was originally conceived, there has been major reorganization and reclassification of this kingdom. In the future, kingdom protista will likely be classified in several kingdoms, and this work is currently ongoing. We use the word “protist” as a convenient term to mean “eukaryote that isn’t a plant, animal, or fungus.”
Many protists are unicellular, but live in colonies. Those that are photosynthetic usually float near the surface of lakes and the oceans and are responsible for half of all of the world’s photosynthesis.
Procedure:
For each of the protists that it asks you to find images (NOT DRAWINGS) of the protists. (You are not finding images of all of them, read carefully.) You will be finding these on the internet.
Take a picture/screenshot of each protist you have “examined”. (Look for the 👀 icon )
Insert your image into the lab with proper Figure captions. Also don’t forget to include where you got your image from. (If I can’t find it, it doesn’t count…) For this lab, just a web address is acceptable. (The google search address is not acceptable, go to the actual site.)
Answer the embedded questions.
Submit your lab on Moodle
Hints: Make sure to use reliable sources, webpages that end in .edu or .gov are usually reliable)
You are not looking at every protist, read carefully. (Examine, looking at are key words…)
Make sure these are actual slides or images, not drawings. You will get NO CREDIT if it is a drawing.
Green Algae
The green algae (Phylum Chlorophyta) may be ancestral to the first plants because both of these groups possess chlorophylls a and b, both store reserve food as starch, and both have cell walls that contain cellulose.
👀You will examine a filamentous form (Spirogyra) and a colonial form (Volvox) of Green Algae.
👀a. Spirogyra
Spirogyra is a filamentous alga that lives in fresh water and is often seen as a green scum on the surface of ponds and lakes. The most prominent feature of the cells is the spiral, ribbon like chloroplast.
What is the purpose of the chloroplast? __________________________
👀b. Volvox
Volvox is a green algal colony. It is motile (capable of locomotion) because each of the cells that make up the colony have two flagella. These cells are connected by delicate cytoplasmic extensions. Volvox is capable of both asexual and sexual reproduction. Certain cells of the adult colony can divide to produce daughter colonies that reside for some time in the parental colony. A daughter colony escapes the parental colony by releasing an enzyme that dissolves away a portion of the matrix of the parental colony. During sexual reproduction, some colonies of Volvox have cells that produce sperm, and others have cells that produce eggs. This is important in the evolutionary development of algae to plants.
What is the purpose of the flagella? __________________________
Can you see the flagella? ________________________________ Describe it.
Brown Algae
Most brown algae (Phylum Phaeophyta) are found in cold, marine environments. Their color is due to the accessory pigment fucoxanthin, which is so abundant that it masks the green chlorophylls. The most important substance extracted from brown algae is, algin, a cell wall component of brown algae that makes ice cream smooth, cosmetics soft, and paint uniform in consistency, among other uses.
Fucus is a common brown alga of the coast, found attached to rocks where it is frequently hit by the waves.
👀Examine Fucus, noting the branching nature of the body.
Is this unicellular or multicellular? _________________________________
Justify your answer, based solely on your picture. __________________________
Red Algae
Like most brown algae, the red algae (Phylum Rhodophyta) are multicellular, but they are found chiefly in warmer seawater, both in shallow and deep waters as red light can penetrate the deepest. Some forms of red algae are filamentous, but more often, they are complexly branched with a feathery, flat, and expanded or ribbon like appearance. Red algae supplies agar, a substance extracted from their cell walls.
What is the importance of agar in microbiology? _____________________________
Diatoms
The cell wall of the diatom is in two sections, and it contains silica which makes it look like glass. Another interesting feature of diatoms is that their cell wall is in two pieces, almost box-like with the top portion sitting on the lower portion. Because of the silica in their cell walls, the diatoms’ cell walls do not decompose when they die, and they form a thick layer on the pond’s floor. This layer is then collected as diatomaceous earth and used in filters and as a natural insecticide. Most diatoms are photosynthetic and extremely abundant, account for 25% of the photosynthesis on Earth.
👀View some diatoms. Find and include at least 4 different shaped diatoms. (They may all be in the same picture.)
PROTOZOANS – “animal-like” protists
The term protozoan refers to unicellular heterotrophs that ingest food. These protists are classified by how they move and how they eat. Some are parasitic but many are not.
Amoeboid protozoans
The best-known amoeboid protozoans are the amoebas, organisms that continually change shape by forming projections called pseudopodia (singular, pseudopodium, “false foot”). Food capture is by way of phagocytosis – the organism surrounds and engulfs a food organism with its pseudopodia, forming a food vacuole. One notorious human pathogen is Entamoeba histolytica, the cause of amoebic dysentery. Another is Naegleria fowleri which causes primary amebic meningoenchephalitis, this is a relatively rare disease but has been found in North Carolina.
👀Examine Amoeba proteus and Entamoeba histolytica. (2 different protists)
Do all amoeboid protozoans cause disease? _________________________
Ciliated protozoans
Most members of the Phylum Ciliophora are covered with numerous short
locomotory structures called cilia. The cilia beat, or move like oars to move the organism. One of the largest ciliates is the predatory Paramecium caudatum. Beating cilia drive food particles into the oral groove of the Paramecium. The particles become enclosed by a food vacuole, where digestion will take place.
👀 Examine didinium, stentor and paramecium caudatum. (There are 3 protists listed here.)
Can you see the cilia on any of these organisms? If so, which ones? _______________
Flagellated protozoans
These protists belong to many phyla and can have one or more flagella to provide motility. The group includes some fairly notorious human parasites that cause disease, including giardiasis (from drinking contaminated water), some sexually transmitted diseases (via Trichomonas vaginalis), and African sleeping sickness, caused by Trypanosoma brucei.
👀 Look at the parasitic flagellates Trypanosoma brucei and trichomonas vaginalis. These will most likely be human blood smears as these parasites travel through the blood.
Euglenoids
The euglenoids are more commonly called euglenas, there are approximately 800 species and are mostly found in freshwater. Most of these species are photosynthetic. These are flagellated protozoans but are not parasitic.
👀Examine an euglena
Sporozoans
All members of the Phylum Apicomplexa are parasites. Plasmodium falciparum causes one type of malaria in humans. (There is more than one type of malaria.) P. falciparum is transmitted to humans through the bite of an infected female Anopheles mosquito. The mosquito serves as a vector, a means of transmitting the organism from one host to another. Male mosquitoes cannot serve as vectors, because they lack the mouthparts for piercing skin and sucking blood.
👀 Examine a blood smear that has a Plasmodium vivax infection.
Plasmodium causes what disease that is the leading killer of pregnant women and children under the age of 5?
What may be a way to stop the spread of Plasmodium? (Hint: think back to your biotechnology lecture?)