1. OXYGEN REVOLUTION Eukaryotes Evolved Anaerobic World (4.6 BYA-)
No oxygen in the atmosphere; No ozone layer, UV radiation bombards earth
Organic Soup
Origin of Life
Anaerobic Chemosynthetic and/or Heterotrophic Bacteria
Anaerobic Photosynthetic Bacteria
One Photosystem
Aerobic Photosynthesis (Blue-green bacteria) 3.5 BYA
Two Photosystems & O2 released
Aerobic World (<2.5 BYA)
Krebs Cycle evolved, ozone layer developed, land could be occupied
Eukaryotes Evolved

2. OXYGEN REVOLUTION
Anaerobic

3. There are 6 known phyla of photosynthetic bacteria widely distributed almost certainly due to horizontal gene transfer. Only the Cyanobacteria is capable of oxygenic photosynthesis. The others don’t produce O2
Science 31 March 2017

4. They evolved the Krebs Cycle
The oxygen revolution killed most anaerobic prokaryotes.
But some prokaryotes evolved a way to deal with the O2. =
Oxygen atom + 2 electrons  O = O
+ 2 H+  H20
They evolved the Krebs Cycle

5. Anaerobic Aerobic Heterotrophic Nutrition Glucose (6C) Glycolysis
Many anaerobic bacteria do this.
2 Pyruvic Acid (3C)
Kreb’s Cycle
Aerobic
Some bacteria can do this

6. KREBS CYCLE/ ELECTON TRANSPORT H2 O is formed O2 is final e- receptor
Pyruvic acid (3C)
KREBS CYCLE/
ELECTON TRANSPORT
H2 O is formed
O2 is final e- receptor
Little ATP produced
CO2 released
Lots of ATP formed
36 ATPs

7. KREBS CYCLE/ ELECTON TRANSPORT H2 O is formed O2 is final e- receptor
Pyruvic acid (3C)
KREBS CYCLE/
ELECTON TRANSPORT
H2 O is formed
O2 is final e- receptor
Little ATP produced
CO2 released
Lots of ATP formed
36 ATPs

8. Electron Transport System On walls of inner membraneX Y G E N
Krebs Cycle
In matrix
Electron Transport System
On walls of inner membrane
Pyruvic acid

9. This could only occur
after
the oxygen revolution

10. PROPOSED BACTERIA EVOLUTION
~2.5 BYA
3.5 BYA
Chemosynthesis

11. Where Did Eukaryotes Come From?
Answer:
They evolved from Prokaryotes
Two Hypotheses:
1) Infolding hypothesis
2) Endosymbiotic hypothesis

12. Evolution of the Eukaryotic Cell
IInfolding hypothesis
Origin of chloroplasts
Origin of mitochondria

13. Evolution of the Eukaryotic Cell
IInfolding hypothesis
Notice: the mitochondria and chloroplasts enter the cell after the membrane system of the cell has become established

14. Evidence for Endosymbiotic Hypothesis of the origin of mitochondria & chloroplasts
Similarities between bacteria & mitochondria & chloroplasts:
Binary fission
Size
Single circular naked DNA
Same sized ribosomes (small)
Protein synthesis inhibited by antibiotics
Enzymes for synthesis of DNA, RNA, Protein similar
Electron transport system in the walls of the structure

15. Eukaryotes have both Archaebacteria & Eubacteria genes
Archaeal genes run processes involving DNA & RNA (informational functions): replication, transcription, & translation
Bacterial genes run metabolic & housekeeping chores (operational functions).

17. Three Domain Tree

18. Two Domain Tree

19. Evolutionary Sequence
Prokaryotes

20. Kingdom Protista

21. PROTISTA
The first Eukaryotes

22. Problems for Protista Who are the Protista? Where did they come from?
How did their structures evolve?
How did sex evolve?
How did mitosis evolve?
How did meiosis evolve?

23. Who are the Protista? Eukaryotic (= true nucleus)
Membrane bound organelles
Usually single celled
Mostly asexual reproduction

24. POLYPHYLETIC

25. Who are the Protista? Three major groups
1) Animal-like Protista = Protozoa
(Lack chloroplasts; classified by locomotion; heterotrophic)
2) Fungal-like Protista
(Lack chloroplasts; produce spores; heterotrophic)
3) Plant-like Protista = Unicellular algae
(Have chloroplasts; photosynthetic; classified by pigments)

26. Animal-like Protista Protozoa
Four major groups
1) Flagellates (move with flagella)
2) Ciliates (move with cilia)
3) Amoebae (move with pseudopods)
4) Sporozoa (lack movement, produce spores)

27. Flagellates= move with flagella
Zooflagellates

28. How are the Protozoa related to multicellular animals?
Choanoflagellates

29. How are the Protozoa related to multicellular animals?
Choanoflagellates = collar cells
Sponges

30. How are the Protozoa related to multicellular animals?
Eumetazoa Parazoa
Choanoflagellates
“True Animals”
Sponges

31. Ciliates= move with cilia
Must be closely related to zooflagellates

32. Amoebae= move with pseudopods
Naked species (= without shells)

33. Amoebae in silicon shells
Radiolarians

34. Amoebae in calcium carbonate shells
Foraminiferans

35. Slime Molds Protista with Fungal-like Characteristics

36. Cellular Slime Mold Note: Amoebae Could Slime molds be related
to amoebae?

37. Where Do Algae Fit In?
Zooflagellates Photoflagellates Ancestral flagellates Since both protozoa & algae have flagella
Protozoa
Single-celled Algae
Chloroplasts

38. Summary of Algae Relationships
Ch a & c Ch a & b
ancestors ancestors
Phytoflagellates
Dinoflagellates
Euglenas
Diatoms
Green Algae
Brown Algae
Red Algae

39. Chlorophylls a & c algae
Dinoflagellates Ch a & c Red Tides

40. 200,000 species 2. Diatoms Ch a & c silicon shells
Most of the oceans’ photosynthesis
20% of world’s photosynthesis by diatoms
200,000 species

41. Multicellular Algae
Brown Algae
Phylum Phaeophyta
Ch a & c
Kelp

42. Chlorophylls a & b algae
Euglenas
Ch a & b
Many heterotrophs

43. Multicellular Algae
Green Algae
Phylum Chlorophyta
Ch a & b

44. Multicellular Algae Red Algae (Phylum Rhodophyta) Ch a & phycoerythrin
Reef building =
Coraline algae secrete calcium carbonate

45. Evolutionary Sequence
Prokaryotes

46. Next Time
PLANTS