1. Please highlight all the terms in blue.
Make sure to study these notes…there will be a quiz over these notes on Monday/Tuesday, January 21st & 22nd.
When you are done with the notes:
Read and study the chapter in the textbook.
Read and review your notes.
Come prepared for discussion and activities in class.

2. Chapter 30: Protists

3. Introduction Domain Eukarya is the third domain on the tree of life.
Eukaryotes range from single-celled organisms the size of bacteria to sequoia trees and blue whales.
Eukaryotes are diverse, yet share fundamental features that distinguish them from bacteria and archaea:
Most are large, have more organelles and a more extensive cytoskeleton
A nuclear envelope
Multicellularity evolved multiple times
Asexual and sexual reproduction

4. Protists Introduction
All eukaryotes except land plants, fungi, and animals.
Tend to live in environments where they are surrounded by water most of the time.

5. Open ocean: Surface waters teem with microscopic protists,
Figure 27.1
Open ocean: Surface waters
teem with microscopic protists,
such as these diatoms.
Shallow coastal waters:
Gigantic protists, such as
these kelp, form underwater
forests.
Intertidal habitats: Protists
such as these brown algae are
particularly abundant in tidal
habitats.
Figure 27.1 Protists Are Particularly Abundant in Aquatic Environments.
1 mm
© 2017 Pearson Education, Inc.

6. Why Do Biologists Study Protists?
Biologists study protists because they have:
Impacts on human health and welfare
Ecological importance
Critical to understanding evolution of plants, fungi, and animals

7. Impacts on Human Health and Welfare
Several types of protists can cause human disease, and some also cause disease in our crops.
Irish potato famine of 1845: caused by the protist Phytophthora infestans
Type of water mold
Led to emigration, and mass starvation caused deaths

8. Malaria is one of the world’s most chronic public health problems
Caused by five species of the parasitic protist Plasmodium and is transferred to humans from mosquitoes.
The cell types that make up each stage of the Plasmodium’s life cycle are each specialized for infecting a specific host cell.

9. Figure 27.2
Haploid (n)
Plasmodium
cell type
present in
mosquito
saliva that
infects
humans
MITOSIS
MITOSIS
Diploid (2n)
Mosquito
bite
(n)
(n)
Infection of liver
cells in human
Human host
Mosquito host
Infec
tion o
f gut w
all in m o
Male
gametes (n)
Figure 27.2 Plasmodium Lives in Mosquitoes and in Humans, Where It Causes Malaria.
squito
Plasmodium
cell types
present in
human blood
that infect
mosquitoes
MEIOSIS
followed by
MITOSIS
Mosquito
bite
Zygote
FERTILIZATION
(2n)
Female
gamete (n)
© 2017 Pearson Education, Inc.

10. Table 27.1 Some Human Health Problems Caused by Protists.
© 2017 Pearson Education, Inc.

11. Protists Play a Key Role in Aquatic Food Chains
Protists represent just 10% of the named eukaryotic species, but they are extraordinarily abundant.
Primary producers—species that produce chemical energy by photosynthesis
Production by marine protists represents almost half of the total carbon dioxide that is fixed on Earth.
Plankton—diatoms and other small organisms that drift in the open oceans or lakes

12. Protists Play a Key Role in Aquatic Food Chains
A food chain describes nutritional relationships among organisms.
Many of the species at the base of food chains in aquatic environments are protists.

13. How Do Protists Obtain Food?
Bacteria and archaea obtain their food in a wide variety of ways.
One of the most important stories in the diversification of protists was the evolution of novel methods for finding food.
Many protists ingest their food—they eat bacteria, archaea, or other protists whole, this process is called phagocytosis.

14. How Do Protists Obtain Food?
Protists feed in various ways:
Ingesting packets of food
Absorbing organic molecules directly from the environment
Performing photosynthesis

15. Ingestive Feeding
Ingestive lifestyles are based on eating live or dead organisms or on scavenging loose bits of organic debris.
Some protists are large enough to surround and ingest bacteria and archaea.
Some protists are large enough to ingest other protists or microscopic animals.

16. Ingestive Feeding
Feeding by phagocytosis is possible in protists that lack a cell wall
A flexible membrane and dynamic cytoskeleton allow them to surround and “swallow” prey with pseudopodia (long, fingerlike projections)
Many ingestive feeders actively hunt prey and other ingestive feeders attach themselves to a surface.
These protists feed by sweeping food particles into their mouth with cilia.

17. (a) Pseudopodia engulf food.
Figure 27.13
(a) Pseudopodia engulf food.
Protist
Prey
1 µm
Pseudopodium
(b) Ciliary currents sweep food into gullet.
Cilia
Figure Ingestive Feeding.
Food
items
Gullet
50 µm
© 2017 Pearson Education, Inc.

18. Absorptive Feeding
Absorptive feeding—nutrients taken up across plasma membrane, directly from the environment.
Some absorptive feeders are decomposers, feeding on dead organic matter, or detritus.
Many absorptive feeders live inside other organisms
If an absorptive species damages its host, it is called a parasite.

19. Photosynthesis Autotrophic protists:
Produce organic compounds via photosynthesis
Range in size from single-cell organisms to giant seaweeds
Use carbon dioxide as primary source of carbon

20. How Do Protists Move?
Many protists actively move to find food or light
Amoeboid motion is a sliding movement observed in some protists that is accomplished by streaming of pseudopodia
Requires ATP
Related to muscle movement in animals
Key immune system cells in humans use amoeboid motion

21. Amoeboid motion via pseudopodia Chaos carolinensis
Figure 27.14
Amoeboid motion via pseudopodia
Chaos carolinensis
Figure Amoeboid Motion Is Possible in Species That Lack Cell Walls.
0.2 mm
© 2017 Pearson Education, Inc.

22. How Do Protists Move?
The other major mode of locomotion involves swimming via flagella or cilia.
Flagella and cilia have identical structures, however:
Flagella are long and are usually found alone or in pairs
Cilia are short and numerous
Even closely related protists can use radically different forms of locomotion.

23. (a) Swimming via flagella (b) Swimming via cilia
Figure 27.15
(a) Swimming via flagella
(b) Swimming via cilia
Figure Many Protists Swim Using Flagella or Cilia.
© 2017 Pearson Education, Inc.

24. How Do Protists Reproduce?
Asexual reproduction
Is based on mitosis and cell division in eukaryotic organisms.
Fission in bacteria and archaea
Results in daughter cells that are genetically identical to the parent.

25. How Do Protists Reproduce?
Sexual reproduction
Is based on meiosis and fusion of gametes
Results in daughter cells that are genetically different from their parents and from each other

26. Life Cycles—Alternation of Generations
Alternation of generations— one phase of life cycle based on a haploid form and another based on a diploid form
Gametophyte—multicellular haploid form
Specialized cells produce gametes (single haploid cells) by mitosis and cell division
Two gametes fuse to produce a diploid zygote

27. Life Cycles—Alternation of Generations
Sporophyte—multicellular diploid form
Specialized cells that produce haploid cells (spores) via meiosis
Spores: are single haploid cells that divide mitotically to form haploid gametophyte

28. Please highlight all the terms in blue.
Make sure to study these notes…there will be a quiz over these notes on Monday/Tuesday, January 21st & 22nd.
When you are done with the notes:
Read and study the chapter in the textbook.
Read and review your notes.
Come prepared for discussion and activities in class.