1. The document discusses protists, the most diverse eukaryotic kingdom. It describes how endosymbiosis led to the evolution of multicellular organisms from prokaryotic ancestors through the incorporation of membrane-bound organelles. 2. Protists are classified based on evolutionary lineages revealed by DNA analysis, though classification remains a work in progress. They exhibit a wide range of motility and fulfill important ecological roles as phytoplankton and zooplankton. 3. Examples like choanoflagellates, Chlamydomonas, and Dictyostelium are used to study the origins of multicellularity and cellular processes like sex determination, communication,

1. Eukaryotes - Protists
BIOL 1307
Ebeling

2. Learning Objectives
1. Describe the characteristics common to all protists
2. Explain how endosymbiosis is involved with the evolution of
multicellular eukaryotic organisms from prokaryotic
ancestors
3. Understand why the protists are the most diverse eukaryotic
kingdom
4. Describe the criteria used to classify protists

3. What is a “protist”
1.
2.
3.

4. Origins of eukaryotes:
division of labor
Eukaryotic cells
contain membrane
bound organelles.
What is the origin of
these organelles?
Golgi apparatus
cell membrane
cytoplasm
endoplasmic
recticulum
(ER)
nucleus
cell wall
chloroplast

5. Membrane infolding hypothesis
Section 15.2 Fig. 15.7

6. Endosymbiosis
Section 15.2 Fig. 15.8

7. Endosymbiont Theory
Lynn Margulis 1970

9. How are protists classified?
Protist classification is a work in
progress!
DNA analysis is leading to changes in
how biologists classify protists.
Classification is changing so that it is
based on common evolutionary
lineage.

12. Motility

13. Why are protists important?
● Phytoplankton
● Zooplankton
Fig. 38.4

14. Ecological roles of protists

15. https://news.berkeley.edu/2012/10/24/did-
bacteria-spark-evolution-of-multicellular-life/
Choanoflagellate

19. http://www.youtube.com/watch?v=
GY_uMH8Xpy0

26. Some protists are helpful in studying origins of multicellularity
Chlamydomonas--unicellular green algae that can reproduce
sexually.
Used to study:
● the evolution of sex
● how individual sex is determined
● how cells of opposite sex recognize each other
Choanoflagellates--single cell or
colonies. These are a sister group
to animals.
Used to study:
● how cells
interact with
each other
● how cells
communicate
with each other
Dictostelium--”Dicty” cellular
slime mold.
Used to study:
● cell movement
● chemotaxis (moving
toward a stimulus)
● cell differentiation