1. Ch. 20 Sec. 1
Protists

2. I. What Is a Protist?
Protists are eukaryotes that are not members of the Plant, Animal, or Fungi kingdoms.

3. A. May include more than 200,000 species
B. Most are unicellular

4. II. Evolution of Protists
The first eukaryotic organisms on Earth
Mitochondria and chloroplasts in eukaryotic cells may have descended from prokaryotes that lived inside larger cells
Chloroplast
Plants and plantlike protists

5. III. Classification of Protists
A. Classified by how they obtain nutrition
Heterotrophs - animal-like protists
Photosynthesizers – plantlike protists
Decomposers and parasites funguslike protists

6. Animallike Protists: Protozoans
Ch. 20 Sec. 2
Animallike Protists: Protozoans

7. Animal-like protists are classified by their means of movement
There are four phyla of animal-like protists:
zooflagellates
sarcodines
ciliates
Sporozoans
Animal-like protists are classified by their means of movement 7

8. I. Zooflagellates Animal-like protists (heterotrophs)
Swim using flagella
Long, whiplike projections
Allow a cell to move
Most have one or two flagella
Some species have many
Fluorescence photomicrographs of chonaoflagellates 8

9. C. Most reproduce asexually 1. Mitosis 2. Cytokinesis
D. Some may reproduce sexually
1. Gametes form through meiosis
2. Gametes fuse 9

10. II. Sarcodines
Pseudopods - temporary cytoplasmic projections used for feeding or movement 10

11. A. Amoebas Flexible, active cells Thick pseudopods
a. Extend out of the central mass of the cell
Amoeboid movement
a. Cytoplasm streams into the pseudopod
b. The rest of the cell follows 11

12. Structures of an Amoeba
Sarcodines use pseudopods for feeding and movement. The amoeba, a common sarcodine, moves by first extending a pseudopod away from its body. The organism’s cytoplasm then streams into the pseudopod. Amoebas also use pseudopods to surround and ingest prey.
Fig Page Sarcodines use pseudopods for feeding and movement. The amoeba, a common sarcodine, moves by first extending a pseudopod away from its body. The organism’s cytoplasm then streams into the pseudopod. Amoebas also use pseudopods to surround and ingest prey. 12

13. 4. Amoebas surround food and engulf it
a. Food vacuole - small cavity in the cytoplasm that temporarily stores food
b. Food digested
c. Nutrients passed to cell
d. Waste stays in vacuole until released outside the cell
5. Amoebas reproduce by mitosis and cytokinesis 13

14. B . Other sarcodines
Foraminiferans
Heliozoans (“sun animals”) 14

15. III. Ciliates Ciliates use cilia for feeding and movement
1. Short hairlike projections
2. Propel a cell
B. Paramecia
1. Cilia
a. Grouped into rows and bundles
b. Beat in a regular pattern 15

16. Structures of a Paramecium
Ciliates use hairlike projections called cilia for feeding and movement. Ciliates, including this paramecium, are covered with short, hairlike cilia that propel them through the water. Cilia also line the organism’s gullet and move its food—usually bacteria—to the organism’s interior. There, the food particles are engulfed, forming food vacuoles. The contractile vacuoles collect and remove excess water, thereby helping to achieve homeostasis, a stable internal environment.
Fig Page Ciliates use hairlike projections called cilia for feeding and movement. Ciliates, including this paramecium, are covered with short, hairlike cilia that propel them through the water. Cilia also line the organism’s gullet and move its food—usually bacteria—to the organism’s interior. There, the food particles are engulfed, forming food vacuoles. The contractile vacuoles collect and remove excess water, thereby helping to achieve homeostasis, a stable internal environment. 16

17. C. Internal Anatomy Trichocysts Bottle-shaped structures
Below the surface of the cell membrane
Used for defense 17

18. 2. Paramecia possess two types of nuclei:
Macronucleus keeps multiple copies of most genes for its day-to-day existence
Micronucleus contains a “reserve copy” 18

19. b. Traps the particles and forces them into food vacuoles
3. Gullet
a. Cilia sweep food in
b. Traps the particles and forces them into food vacuoles
c. The food vacuoles fuse with lysosomes
i. contain digestive enzymes
4. Anal pore
a. After digestion, the waste material empties through the anal pore 19

20. 5. Contractile vacuoles - cavities in the cytoplasm
a. Specialized to collect water
b. In fresh water: osmosis
c. Excess collected in vacuoles
d. Contract, pumping water out
e. Maintain homeostasis 20

21. D. Conjugation
Reproduction is usually asexual by mitosis and cytokinesis
Conjugation - When placed under stress 21

22. Two paramecia attach themselves to each other.
Meiosis produces four haploid micronuclei, three of which disintegrate.
The remaining micronucleus in each cell divides again.
Macronucleus
Micronucleus
MEIOSIS
During conjugation, two paramecia attach themselves to each other and exchange genetic information. The process is not reproduction because no new individuals are formed. Conjugation is a sexual process, however, and it results in an increase in genetic diversity.
See Fig Page During conjugation, two paramecia attach themselves to each other and exchange genetic information. The process is not reproduction because no new individuals are formed. Conjugation is a sexual process, however, and it results in an increase in genetic diversity. 22

23. The two cells exchange one micronucleus from each pair.
The macronuclei disintegrate, and each cell forms a new macronucleus from its micronucleus.
During conjugation, two paramecia attach themselves to each other and exchange genetic information. The process is not reproduction because no new individuals are formed. Conjugation is a sexual process, however, and it results in an increase in genetic diversity. 23

24. Conjugation is not a form of reproduction
Conjugation is not a form of reproduction. In large populations, conjugation helps produce and maintain genetic diversity.
Genetically identical paramecia form
During conjugation, two paramecia attach themselves to each other and exchange genetic information. The process is not reproduction because no new individuals are formed. Conjugation is a sexual process, however, and it results in an increase in genetic diversity. 24

25. IV. Sporozoans Immobile Parasitic 1. Worms 2. Fish 3. Birds 4. Humans25

26. Sporozoans reproduce by sporozoites.
Many sporozoans have complex life cycles that involve more than one host.
Sporozoans reproduce by sporozoites.
A sporozoite can attach itself to a host cell, penetrate it, and then live within it as a parasite. 26

27. V. Animal-like Protists and Disease
Some animal-like protists cause serious diseases, including malaria and African sleeping sickness. 27

28. A. Malaria
Malaria is one of the world’s most serious infectious diseases, killing as many as 2 million people each year.
The sporozoan Plasmodium, which causes malaria, is carried by the female Anopheles mosquito. 28

29. Malarial Infection
Animal-like protists can cause serious diseases, including malaria. The bite of an Anopheles mosquito can transmit Plasmodium sporozoites. Once in the human body, Plasmodium infects liver cells and red blood cells and multiplies.
Fig Animal-like protists can cause serious diseases, including malaria. The bite of an Anopheles mosquito can transmit Plasmodium sporozoites. Once in the human body, Plasmodium infects liver cells and red blood cells and multiplies. 29

30. A female Anopheles mosquito bites a human infected with malaria and picks up Plasmodium gamete cells.
Animal-like protists can cause serious diseases, including malaria. The bite of an Anopheles mosquito can transmit Plasmodium sporozoites. Once in the human body, Plasmodium infects liver cells and red blood cells and multiplies. 30

31. The sexual phase of the Plasmodium life cycle takes place inside the mosquito.
Gametes fuse to form zygotes, meioses occurs, and sporozoites are produced and migrate to salivary gland.
Animal-like protists can cause serious diseases, including malaria. The bite of an Anopheles mosquito can transmit Plasmodium sporozoites. 31

32. Infected mosquito bites another human, injecting saliva that contains Plasmodium sporozoites.
Animal-like protists can cause serious diseases, including malaria. The bite of an Anopheles mosquito can transmit Plasmodium sporozoites.
Plasmodium sporozoites 32

33. Sporozoites infect liver cells and multiply asexually.
Plasmodium sporozoites
Liver
Animal-like protists can cause serious diseases, including malaria. The bite of an Anopheles mosquito can transmit Plasmodium sporozoites. Once in the human body, Plasmodium infects liver cells and red blood cells and multiplies. 33

34. Infected liver cells burst, releasing Plasmodium cells called merozoites that infect red blood cells.
Plasmodium sporozoites
Liver
Animal-like protists can cause serious diseases, including malaria. The bite of an Anopheles mosquito can transmit Plasmodium sporozoites. Once in the human body, Plasmodium infects liver cells and red blood cells and multiplies.
Merozoites
Liver cells burst 34

35. Merozoites reproduce asexually inside red blood cells.
Once in the human body, Plasmodium infects liver cells and red blood cells and multiplies.
Red blood cells 35

36. Infected red blood cells burst, releasing merozoites that infect other red blood cells. Some cells release gametes that can infect mosquitoes.
Merozoites
Animal-like protists can cause serious diseases, including malaria. The bite of an Anopheles mosquito can transmit Plasmodium sporozoites. Once in the human body, Plasmodium infects liver cells and red blood cells and multiplies.
Red blood cells 36

37. B. Other Diseases Caused by Protists
African sleeping sickness
Amebic dysentery
Giardia 37

38. VI. Ecology of Animal-like Protists
A. Many animal-like protists are essential to the living world
Some live symbiotically within other organisms
Some recycle nutrients from dead organic matter
Some live in water, where they are eaten by tiny animals, which in turn serve as food for larger animals 38

39. B. ex: Trichonympha 1. Lives in the digestive systems of termites
2. Breaks down cellulose
3. Allows termites to digest wood 39

40. 20–1 The Kingdom Protista
The kingdom Protista is a diverse group. Protists are eukaryotes that are not members of the kingdoms Plantae, Animalia, or Fungi. Most protists are unicellular. Earth’s first eukaryotes were protists.
One way protists are classified is according to how they obtain nutrition.
Thus, many protists that are heterotrophic are called animallike protists.
Protists that produce their own food by photosynthesis are called plantlike protists.
Protists that obtain their food by external digestion are called funguslike protists.

41. 20–2 Animallike Protists: Protozoans
Animallike protists are called protozoans. Protozoans are heterotrophs.
There are four phyla of animallike protists. They are
classified according to how they move.
• Protists that swim using flagella are classified in the phylum Zoomastigina. They are called zooflagellates. Flagella are long, whiplike projections that allow a cell to move.
• Members of the phylum Sarcodina move by using pseudopods. Sarcodines also use pseudopods for feeding.
Pseudopods are temporary projections of cytoplasm.
Sarcodines called amoebas have thick pseudopods. An
ameoba moves by first extending its psuedopod. The cell’s
cytoplasm flows into the pseudopod. The rest of the cell
then follows. This type of movement is called amoeboid
movement.

42. • Members of the phylum Ciliophora, known as ciliates, use cilia for feeding and movement. Cilia are short, hairlike projections similar to flagella. Some of the best-known ciliates belong to the genus Paramecium. The cilia of a paramecium are organized into evenly spaced rows and bundles. Just under the cell membrane, a paramecium has small defense structures called trichocysts. When a paramecium is in danger, the trichocysts release stiff projections that protect the cell.

43. • Members of the phylum Sporozoa do not move on their own
• Members of the phylum Sporozoa do not move on their own. They are parasites that reproduce by means of sporozoites. Some animallike protists cause serious diseases. For example, Plasmodium is a sporozoan that causes malaria. Trypanosoma is a zooflagellate. It causes African sleeping sickness. Some animallike protists are helpful. Trichonympha lives in the digestive system of termites. This protist helps termites digest wood.