1. Biology

2. Chapter 15 Protists I. Characteristics of Protists
A. Live wherever there is water
1. Oceans, ponds, mud puddles, snow, inside organisms
B. All are eukaryotic
C. Can be either unicellular or multicellular
D. Broken into groups based on how they obtain nutrition
1. Animal-like, Plant-like, & Fungus-like

3. II. Protozoans – animal-like protists
A. All are unicellular heterotrophs
B. Classified into four groups(phyla) based on how they move.
1. Sarcodina – move by extending lobes of cytoplasm
a. Some have shells and extend lobes through the holes of shells
ex – foramniferans
b. Amoeba – move by means of cytoplasmic projections called
pseudopods (false feet)
1) Is constantly extending and retracting pseudopods and has
no definite shape.
2) Uses pseudopods to surround and capture food.
(phagocytosis)
3) Can become a hard cyst in unfavorable conditions

4. a) People may ingest these in food or water and become
infected with parasitic amebas.
ex – amebic dysentery
4) Reproduce asexually by binary fission
2. Zooflagellates – have one or more flagella for movement.
a. Some live in organisms in symbiotic relationships.
1) Trichonympha – live in the gut of termites and help digest the
wood.
2) Trypanosoma – live in the blood of host as a parasite

5. 3. Ciliates(Ciliophora) – move by tiny hair-like structures called cilia.
a. Most numerous and diverse group.
b. Paramecium – use cilia like boat oars to move thru the water.
c. Most live in freshwater.
d. Can also form cysts and a majority are harmless.
4. Sporozoans – are parasitic and lack structures for movement.
a. Do not form true spores.
b. Life cycles are complex and include sexual and asexual phases.
c. Plasmodium – infects both mosquitoes and humans.
1) Causes malaria

6. The sporozoites pass quickly into the human liver.
Malaria infection begins when an infected female Anopheles mosquito bites a person, injecting Plasmodium parasites, in the form of sporozoites, into the bloodstream.  
The sporozoites pass quickly into the human liver.  
The sporozoites multiply asexually in the liver cells over the next 7 to 10 days, causing no symptoms.  
In an animal model, the parasites, in the form of merozoites, are released from the liver cells in vesicles, journey through the heart, and arrive in the lungs, where they settle within lung capillaries. The vesicles eventually disintegrate, freeing the merozoites to enter the blood phase of their development.*  
In the bloodstream, the merozoites invade red blood cells (erythrocytes) and multiply again until the cells burst. Then they invade more erythrocytes. This cycle is repeated, causing fever each time parasites break free and invade blood cells.   .

7. Some of the infected blood cells leave the cycle of asexual multiplication. Instead of replicating, the merozoites in these cells develop into sexual forms of the parasite, called gametocytes, that circulate in the blood stream.  
When a mosquito bites an infected human, it ingests the gametocytes, which develop further into mature sex cells called gametes.  
The fertilized female gametes develop into actively moving ookinetes that burrow through the mosquito's midgut wall and form oocysts on the exterior surface.  
Inside the oocyst, thousands of active sporozoites develop. The oocyst eventually bursts, releasing sporozoites into the body cavity that travel to the mosquito's salivary glands.  
The cycle of human infection begins again when the mosquito bites another person.

8. III. Algae – Plant-like Protists
A. Can perform photosynthesis
B. Unicellular Algae
1. Dinoflagellates – have thick cell walls made up of cellulose plates.
a. Have two flagella and are marine
b. Red Tides – population explosion of red pigmented dinoflagellates.
1) Produces poisonous toxins that kills tons of fish.
2. Diatoms – have glass-like cell walls containing silica.
a. Have thousands of different shapes and patterns.
b. Have pores in the cell walls to allow things in and out.
3. Euglenoids – resemble both algae and protozoans.
a. Most contain chlorophyll and make their own food.
b. Lack rigid cell walls and move using flagella

9. C Multicellular Algae – are classified by color
1. Red Algae
a. Live in deep water and have lots of red and blue pigments.
1) Help to carry on photosynthesis where light is limited.
b. Most live in warm tropical saltwater habitats
2. Brown Algae
a. Grow mostly in cooler saltwater along rocky coasts
b. Kelp – largest of all algae – up to 100 m long
1) Have air bladders that cause leaf portion to float
2) Holdfasts – structure that “anchors” them to the bottom

10. 3. Green Algae
a. Major pigment is chlorophyll
b. Most live in freshwater, but some are found in moist soil, tree trunks,
and snow.
c. Colony – group of cells that live together in close association.
ex - Volvox

11. IV. Fungus-like Protists – molds
A. Most live in damp or watery places and breakdown dead organic matter.
B. Broken into 3 Groups
1. Plasmodial Slime Molds
a. Plasmodium – single cell with many nuclei
1) The feeding stage of the slime mold
b. Produce a fruiting body when conditions are unfavorable
1) Produces spores that can remain dormant for years.
2. Cellular Slime Molds – alternate between spore producing form and
ameba-like eating form.
a psuedoplasmodium – clumps of cells that produce fruiting bodies
3. Water Molds – decomposers in freshwater systems
a. Some attack inured skin or gill tissue of fish
b. Some are parasites of land plants.

12. V. Protists in the Biosphere
A. Ecological Roles
1. Are the essential food base in aquatic food chains (Plankton)
2. Help to maintain Earth’s oxygen and carbon dioxide levels
a. Perform 70% of all photosynthesis
3. Keep the number of bacteria in check by killing and eating them.
B. Diseases
1. Trypanosoma – African Sleeping Sickness.
2. Giardia – cysts will cause intestinal problems.
3. Plasmodium - malaria

13. C. Human Uses
1. Food – some are eaten directly in “seaweed” form.
a. Carrageenan – thickener and flavor enhancer added to dairy products
1) Chocolate milk and milk shakes(carageenan – red algae)
b. Agar – thicken soups, pudding, and frosting
2. Bioindicators – presence or absence gives indication of the health of a
biosystem.