1. Evolution of Protists
Chapter 19
Section 1 p. 540

2. Between 2 and 1.8 billion years ago……
One type of prokaryotic cell grew large and evolved membranes around its organelles
Some membrane formed nuclear envelope
Result =eukaryotes
Even more remarkable…some prokaryotic organisms entered this ancestral eukaryotic cell
Symbiotic relationshipmutualism

3. The prokaryotes were special
They had the ability to use oxygen to generate energy (ATP). Over time they evolved together
Small cells became mitochondria and chloroplasts

8. What is a Protist? Protists are Eukaryotes!
They have a membrane bound nucleus with membrane bound organelles
This kingdom does not share any unique characteristics…
Most protists are unicellular but some are multicellular!
Many are microscopic but some can grow up to 70 meters long!

9. Protists continued
Most protists need oxygen to survive but some are poisoned by it.
Some protists are autotrophic and others are heterotrophic
Three types of protists
Plant like
Animal like
Fungus like
Some reproduce asexually and other sexually
Some can alternate between!

10. Classification
Many protists have more in common with multicellular kingdoms such as fungi, animalia, and plant than they do with each other!
They do not develop the multicellular structures found in those kingdoms so they must be classified on their own
They are classified as what they are not
An eukaryote that is not classified as a fungus, plant or animal is classified as a protist.
Video

11. Evolution of Sexual Reproduction
300 million years after single-celled eukaryotes first appeared they started evolving quickly
Sexually reproducing
Lots of genetic variation
After the evolution of sexual reproduction, adaptive radiation occurreddiverse

12. Living Protists – Autotrophic or Heterotrophic
Algae – photosynthetic autotrophs that look and act like plants
30 to 40% of all photosynthesis performed by these protists !
Some are very small – some are as long as 70 meters (Giant kelp)

13. Here are two examples of a protist that can grow up to 70 meters in length and sometimes longer. What do you think it is? Where would you find it?

14. Algae Groups Euglenophyta Pyrrophyta Chrysophyta Chlorophyta
Rhodophyta
Phaeophyta
UNICELLULAR
MULTICELLULAR

15. Heterotrophic Protists (protozoans)
All heterotrophic protists spend most of their lives as unicellular – some gather into groups
Slime molds
Heterotrophs live as predators, decomposers or parasites
Sporazoa
Complex parasites – can cause disease
Plasmodium - malaria

16. Autotroph
Heterotroph

17. How do Protists Reproduce?
Euglenophyta reproduce only asexually
All other phyla can reproduce sexually at least occasionally
Slime molds can spend most of their lives like ameba-like cells but under certain conditions can gather into a slug-like mass

18. Fruiting body

19. Repro Continued
Forms a fruiting body that releases spores that then develop into a slug-like mass
Alternation of generations – sporophytes produce haploid spores
Spores grow into male and female cells called gametophytes
Gametophytes produce egg and sperm
Fusion of these gametes produces a zygote which grows into a sporophyte again

20. Keys points to remember
All protists are eukaryotic
Algae are photosynthetic autotrophs
Protozoans are heterotrophs
Asexual repro occurs by mitosis
Sexual repro occurs by fruiting bodies
Alternation of generations between sexual and asexual stages

21. Slime mold travel
Ant head
NPR Encyclopedia of Life