1. 28
Protists

2. Living Small
Even a low-power microscope can reveal a great variety of organisms in a drop of pond water
Protist is the informal name of the group of mostly unicellular eukaryotes
Advances in eukaryotic systematics have caused the classification of protists to change significantly

3. Concept 28.1: Most eukaryotes are single-celled organisms
Protists are eukaryotes
Eukaryotic cells have organelles and are more complex than prokaryotic cells
It is important to bear in mind that
The organisms in most eukaryotic lineages are protists, and
Most protists are unicellular

4. Protists, the most nutritionally diverse of all eukaryotes, include
Photoautotrophs, which contain chloroplasts
Heterotrophs, which absorb organic molecules or ingest larger food particles
Mixotrophs, which combine photosynthesis and heterotrophic nutrition

5. Mitochondria and plastids are derived from prokaryotes that were engulfed by the ancestors of early eukaryotic cells
Mitochondria evolved once by endosymbiosis of an alpha proteobacterium
Plastids evolved later by endosymbiosis of a photosynthetic cyanobacterium
The plastid-bearing lineage of protists evolved into photosynthetic protists, red and green algae

6. Membranes are represented as dark lines in the cell.
Figure 28.3
Dinoflagellates
Membranes are represented as dark lines in the cell.
Secondary endosymbiosis
Red alga
Cyanobacterium
Plastid 1 2 3
Primary endosymbiosis
Stramenopiles
Nucleus
Secondary endosymbiosis
Plastid
Heterotrophic eukaryote
One of these membranes was lost in red and green algal descendants.
Figure 28.3 Diversity of plastids produced by endosymbiosis
Euglenids
Secondary endosymbiosis
Green alga
Chlorarachniophytes

7. Red Algae
Red algae are reddish in color due to an accessory pigment called phycoerythrin, which masks the green of chlorophyll
Red algae are usually multicellular; the largest are seaweeds
Red algae are the most abundant large algae in coastal waters of the tropics
Plants are descended from the green algae

8. ► Bonnemaisonia hamifera
Figure 28.21
► Bonnemaisonia hamifera
20 cm
8 mm
◀ Dulse (Palmaria palmata)
▼ Nori
Figure Red algae

9. Similarities and Differences in the Protist Kingdom
All are eukaryotes (cells with nuclei).
Live in moist surroundings.
Unicellular or multicellular.
Autotrophs, heterotrophs, or both.
Some can move - others cannot.

10. Three categories of Protists:
Animal- Like
Plant – Like
Fungus -like

11. Animal-like Protists (Protozoans)
Unicellular Heterotrophs
Four groups based on movement:
Pseudopods: False feet
zooflagelletes: Have flagella
Ciliates: Have cilia
Sporozoans: Mostly parasitic

12. Pseudopods Reproduce by mitosis
Contractile vacuole - collects extra H2O & expels it from cell
Thin cell membrane and no definite shape. E.g Amoeba
Form pseudopods to surround & trap food. Then form a food vacuole to break down food in the cytoplasm.

13. Pseudopods also called ‘false feet’
Cell membrane pushes in one direction & the cytoplasm flows into the bulge.
This allows the protozoan to move, dragging the rest of the cell behind it.
Pseudopod Movement
PUSH
FLOW
DRAG

14. Ciliates
Cilia - hairlike structures - help organisms move, get food and sense environment.
Multicellular with 2 nuclei.
1 nuclei controls everyday functions and 1 nuclei is for reproduction.
Reproduce by mitosis or conjugation.
Oral groove lined with cilia - moves H20 containing food into food vacuole at end of oral groove.
Food vacuole breaks down food and sends through cell.
Anal pore sends out waste.
Example of protozoan w/ cilia: paramecium.

15. (a) Feeding, waste removal, and water balance.
Figure 28.17a
Contractile vacuole
Oral groove
Cell mouth
Cilia
50 μm
Micronucleus
Food vacuoles
Macronucleus
Figure 28.17a Structure and function in the ciliate Paramecium caudatum (part 1)
(a) Feeding, waste removal, and water balance.

16. The original macro- nucleus disintegrates. Diploid micronucleus
Figure 28.17b-2
Compatible mates
Conjugation
Asexual reproduction
MEIOSIS
Haploid micronucleus
Diploid micronucleus
The original macro- nucleus disintegrates.
Diploid micronucleus
MICRO- NUCLEAR FUSION
Figure 28.17b-2 Structure and function in the ciliate Paramecium caudatum (part 2, step 2)
(b) Conjugation and reproduction.

17. zooflagellates Use long whiplike part called flagella to move.
These usually live inside other organisms.

18. Sporozoans Mostly parasites Feed on cells & body fluids of hosts
Sporozoans like Plasmodium (causes malaria) have more than 1 host: mosquitoes and then humans

19. Funguslike Protists Like animals, they are heterotrophs
Like plants, they have cell walls
Reproduce by spores (tiny cells that can grow into a new organism)
Not in fungi kingdom because they can move at one point in their lives.
Example are water or slime molds.

20. Plantlike Protists Better known as algae Autotrophs
Size: unicellular to very large
Contain different pigments so they come in different colors.
Euglena: special type of algae -when there is no sunlight they become heterotrophic.

21. Concept 28.6: Protists play key roles in ecological communities
Protists are found in diverse aquatic and moist terrestrial environments
Protists play two key roles in their habitats: that of symbiont and that of producer
Some protist symbionts benefit their hosts
Dinoflagellates nourish coral polyps that build reefs
Wood-digesting protists inhabit the gut of termites

22. Some protists are parasitic
Plasmodium causes malaria
Pfiesteria shumwayae is a dinoflagellate that causes fish kills
Phytophthora ramorum causes sudden oak death
P. infestans causes potato late blight, which contributed to the Irish famine of the 19th century

23. Photosynthetic Protists
Many protists are important producers that obtain energy from the sun
In aquatic environments, photosynthetic protists and prokaryotes are the main producers
In aquatic environments, photosynthetic protists are limited by nutrients
These populations can explode when limiting nutrients are added

24. Prokaryotic producers
Figure 28.29
Other consumers
Herbivorous plankton
Carnivorous plankton
Figure Protists: key producers in aquatic communities
Prokaryotic producers
Protistan producers

25. Biomass of photosynthetic protists has declined as sea surface temperature has increased
Growth of phytoplankton communities relies on nutrients delivered from the ocean bottom through the process of upwelling
Warm surface water acts as a barrier to upwelling

26. If sea surface temperature continues to warm due to global warming, this could have large effects on
Marine ecosystems
Fishery yields
The global carbon cycle

27. Fungi Kingdom

28. Nutrition and Ecology
Fungi are heterotrophs and absorb nutrients from outside of their bodies
Fungi use enzymes to break down a large variety of complex molecules into smaller organic compounds
The versatility of these enzymes contributes to fungi’s ecological success

29. Fungi exhibit diverse lifestyles
Decomposers: Fungi are efficient decomposers of organic material including cellulose and lignin. They perform essential recycling of chemical elements between the living and nonliving world.
Mutualists: Fungi form mutualistic relationships with plants, algae, cyanobacteria, and animals. They help break down plant material in the guts of cows and other grazing mammals. Many species of ants use the digestive power of fungi by raising them in “farms”
Parasites: Each year, 10% to 50% of the world’s fruit harvest is lost due to fungi. Some fungi that attack food crops are toxic to humans

30. (b) Tar spot fungus on maple leaves
Figure 31.24
(b) Tar spot fungus on maple leaves
Figure Examples of fungal diseases of plants
(a) Corn smut on corn
(c) Ergots on rye

31. Eukaryotes
Use spores to reproduce
Heterotrophs that feed on other organic matter like plants
Need warm, moist places to grow
Examples: yeast, molds, mildew, and mushrooms

32. Fungi –Method of Nutrition
Use a structure called hyphae to get their food, except yeast
Hyphae: threadlike, cytoplasm-filled tubes with nuclei
Shape of fungi depends on how hyphae is used.
The fungal hyphae grows into food then secrete digestive chemicals into food & absorb it
Stolons – horizontal hyphae
Rhizoids- hyphae forming rootlike structures

33. Reproduction in Fungi
Produce thousands of spores with a protective covering: carried by water and air.
spores land in a warm, moist place they form more fungi
When there is plenty of moisture, fungi reproduce asexually by releasing spores.
When conditions are not good, they reproduce sexually.

34. YEAST:
Yeast are unicellular, they reproduce by budding. A well fed cell grows from the body of the mother cell and breaks off from the mother.

35. Practical Uses of Fungi
Humans eat many fungi and use others to make cheeses, alcoholic beverages, and bread
Some fungi are used to produce antibiotics for the treatment of bacterial infections
For example, the ascomycete Penicillium

36. Genetic research on fungi is leading to applications in biotechnology
For example, scientists are using Saccharomyces to study homologs of the genes involved in Parkinson’s and Huntington’s diseases
Insulin-like growth factor can be produced in the fungus Saccharomyces cerevisiae
Gliocladium roseum, a fungus that produces hydrocarbons similar to diesel fuel, could be used to produce biofuels