1. The Protists
Chapter 20

2. What is a protist? A mixed bag of organisms Anything that is not a
plant
animal
fungi
prokaryote

3. General characteristics
Eukaryotic
Can be single-celled, colonial, or multicellular
Some are microscopic but not all
Can reproduce sexually and asexually

6. When did they evolve?
Fossils of eukaryote protists date back to about 1.5 billion years ago.

7. How did they get their organelles?
1)By endosymbiosis (Margulis’s hypothesis)
- a prokaryotic cell engulfed another cell that could carry on photosynthesis or aerobic respiration and those became chloroplasts and mitochondria.
2) Infolding of cell membrane (endocytosis) to enclose DNA (nucleus) and make ER and Golgi complexes

8. endocytosis
endosymbiosis

9. Protists are difficult to classify.
Protista is one kingdom in the domain Eukarya.

10. Protist classification will likely change.
Some protists are not closely related.
Molecular evidence supports reclassification.

11. How are they generally classified?
By their mode of nutrition
This is NOT an evolutionary classification
1) plant-like - autotrophic
2) animal-like - heterotrophic
3) fungi-like - those that live on dead and decaying matter (saprophytic)

12. Protist Category
How they get
their food
Body Form
Animal-like
Single-celled, colonial, or multicellular
decomposer
multicellular

13. Protist Category
How they get
their food
Body Form
Animal-like
heterotrophic
Single-celled
Plant-like
Autotrophic
photosynthetic
Single-celled, colonial, or multicellular
Fungi-like
Decomposer
saprophytic
multicellular

14. Are protists more closely related to animals or to bacteria?

15. What type of protist is moe closely related to animals?

16. Animal-like Protists – classified by how they move
Generally called Protozoa
(proto – first; zoa – animal)
Most reproduce asexually by binary fission

17. Protozoa with Flagella ex Peranema

18. Some are important disease-causers.
Importances:
Some live inside of other animals such as in termites to help them digest wood.
Some are important disease-causers.

19. This flagellate Trichonympha – lives in termite guts
This flagellate Trichonympha – lives in termite guts. The protist gets food and shelter. The termite has something to digest the wood!

20. Protozoa with Pseudopodia
Pseudopodia (false foot) result from streaming of cytoplasm (amoeboid movement), used for movement and food gathering
Ex – amoeba, forams

21. Amoeba
Exhibition of Movies on Protists

22. Amoeba capture their food by surrounding it with their pseudopodia.

23. Forams
Foraminiferans (forams) are “shelled” amoebas. They have pores in their shells in which the pseudopodia could stream out for movement.

25. Forams shells make up beach sand in the Caribbean.

26. The White Cliffs of Dover
Impressive and dramatic, the White Cliffs of Dover keep watch as a citadel over the southern entrance into the Strait of Dover, which separates England from France. They are made of forams in addition to limestone deposits.

27. Protozoa with Cilia Cilia are short, hair-like structures Unicellular
Most are free-living
Ex - Paramecium

29. Paramecium diagram. The parts are as follows: 1) food vacuoles 2) micronucleus 3) oral groove 4) gullet 5) anal pore 6) contractile vacuole 7

30. Structural Features
They have contractile vacuoles to pump out excess water.
They have two nuclei: micronucleus and macronucleus. Micronuclei are exchanged in conjugation

31. Conjugation in Paramecium
They exchange micronuclei –
adds genetic diversity

33. Animal-like Protists that Cause Disease
Trypanosoma – African Sleeping sickness, transmitted by tsetse fly
Plasmodium – causes malaria, transmitted by mosquitoes
Giardia – causes intestinal problems, found in contaminated water

34. Trypanosoma
Causes African sleeping sickness

35. Life cycle of a plasmodium
in malaria. It moves through a mosquito and then to humans.

36. Giardia – bad boy in bad water

37. Plant-like Protists
Not like plants – no roots, stems, leaves, or same reproductive structures
Make up large part of phytoplankton
Photosynthetic, unicellular protists are called algae
Larger forms are called seaweeds

38. In this group are unicellular, colonial, and multicellular organisms

39. Euglenoids Ex- Euglena Single-celled, have flagella
No cell wall, pellicle covering instead
Have red eyespot for detecting light
Are myxotrophic (can be autotrophic and heterotrophic)

41. Dinoflagellates Called “fire plants” because some are bioluminescent
Unicellular
Some are auto, some are heterotrophic
Have armor-like cell walls, 2 flagella
Cause red tides (algae blooms) that are toxic to fish
Some help build coral reefs

44. Diatoms
Unicellular
Cell walls made of silicon glass that fit into each other like a petri dish
Major part of plankton, produce about ½ of oxygen we breathe
Make diatomaceous earth for abrasives cleaners, pesticides, and filters
Found in fresh and salt water

46. Multicellular algae are classified by their pigments.
Green algae
Brown algae
Red algae

47. Green Algae Found in fresh and salt water and on land
Contain pigments chlorophyll a and b and carotenoids
Can be unicellular, colonial, or multicellular
Share similarities with plants (ancestors)
- cellulose cell walls
- same chlorophyll pigments
- store food as starch
Can cause algae blooms

48. Unicellular
Multicellular
Colonial

49. Volvox
A colonial
algae
Daughter cells

51. Brown Algae Marine, multicellular Contains chlorophyll c
Largest seaweeds (contains the Kelp)
Used as food

52. Red Algae Marine, multicellular Contain red pigments in
addition to chlorophyll
Seaweeds that live
at great depths
Have mutualistic
symbiotic relationships
with coral animals and forams
Used commercially in milk products, cosmetics, sushi, ice cream

54. Reproduction
The plant-like protists can reproduce both sexually and asexually with some alternating stages.

55. Fungi-like Protists
Like fungi in that they are decomposers and have similar structures (hairy and produce spores on stalks)
Different from fungi since some have cells (spores) that can move
Main groups:
slime molds
water molds

56. Slime Molds Important decomposers Two types:
Plasmodial (large multinucleate mass)
Cellular (individual cells congregate
to form a mass called a
pseudoplasmodium.

57. A plasmodial slime mold

58. Forming a pseudoplasmodium from individual cells

59. Under stressful conditions, they will form stalks with spores
Stalk with spores
Plasmodium

60. Water Molds May appear as white fuzz on dead things
Fungi-like due to hairy (hyphae) structures
Important disease causers
Great Potato Famine in Ireland in caused mass migration of people to the US

61. Hyphae

62. Importances of the Protists
Recyclers and decomposers
Carry on ½ of world’s photosynthesis
Important in symbiotic associations
ex – trichonympha in termite guts to help
digest cellulose
Food supply
Homes for organisms (seaweeds)
Commercial products
Disease causers – infect water supply, also many parasitic diseases such as malaria