1. Eukaryotes fossil eukaryotes 2 bya “true nucleus”
(prokaryote = “before nucleus”)
linear chromosomes
membrane bound compartments
Figs 6.9, 6.6

2. Eukaryotes distinctive flagella: 9 + 2 microtubules
inserted into cytoplasm
surrounded by membrane
Fig 6.24

3. Independent origin of flagella
Prokaryotes
globular protein flagellin
attached to outer membrane
Fig 27.6
note: singular of flagella is flagellum
similar to bacteria & bacterium

4. Origin of Eukaryotic Cell Fig 25.9

5. Serial Endosymbiosis Theory
explains how eukaryotic cell evolved
prokaryotic symbionts evolved into mitochondria & chloroplasts
symbiont lives INSIDE host cell (intracellular symbiont)
starts as prey (not digested) or parasite (not lethal)

6. Serial Endosymbiosis Theory
symbiont genes move to host nucleus
proteins transported to symbiont
symbiont & host become dependent
new organism has evolved
well accepted; lots of evidence:

7. 1. Similarities between bacteria & mitochondria and plastids
Size
Circular DNA w/out assoc. proteins
Binary fission
Ribosome size, biochemistry
RNA sequence data

8. 2. Eukaryotic cell biology
DNA from organelle in host nucleus
Some DNA still in organelle
Euk. cells deprived of mito & chlplst CANNOT reproduce them

9. 3. Evidence of Past Symbiosis
Glaucophytes
Chlplst CANNOT live indply
Chlplst has small peptidoglycan wall

10. 4. Modern Day Symbiosis Paramecium bursaria
Host and symbiont CAN live indply
Remove symbionts, host re-acquires

11. Types of Endosymbiosis Fig 28.2
Primary: symbiont is prok.
2 chlplst membranes
Secondary: symbiont is euk.
Evidence for 2ndary endosymbiosis:
Extra chlplst membranes
Remains of nucleus = nucleomorph (in two lineages)

12. protist = “the very first”
Modern relatives of earliest euk.
“protists” = eukaryotes that are NOT plants, animals, or fungi
60,000 species known
diverse lineages not closely related
heterotrophs, autotrophs in same lineage (also mixotrophs)
all w/ PS have chlorophyll a; accessory pigments vary between lineages

13. body forms of “protists”
unicells, colonies, multicellular relatives
diversity of form within lineages
unicellular—>multicellular many times
complex unicells: all functions one cell
larger multicellular protists provide habitat

14. ecological roles of “protists”
unicellular (chemo)heterotrophs = protozoa
Protozoology
(photo)autotrophs = algae
Phycology or Algology (includes photosynthetic protists & cyanobacteria)
primary producers, base of food web
small protists are plankton
zooplankton & phytoplankton
Fig 28.28

15. role of plankton in C cycle
PS: H2O + CO2 --> (CH2O) + O2
die & fall as “marine snow”
C sinks
resistant compounds degrade slowly
CO2 removed from atmosphere

16. phytoplankton decline
water transparency
secchi disk
since 1899
>100 yrs of data
chlorophyll conc.
temp increase
Nature July 29, 2010 16