Endosymbiosis

Question 1

How long ago was the big bang?

Answer 1

13.7 bya

Question 2

How long ago was earths creation?

Answer 2

4.5 bya

Question 3

When did microbial life arose?

Answer 3

3.5-4 bya

Question 4

When was “early” life on earth?

Answer 4

3.5-3 bya

Question 5

What are the characteristics of “early life on earth”?

Answer 5

• Prokaryotes rules the planet
• Archea diverged during this period
• Evidence for prokaryotic dominance from this period fossilized in stromatolites

Question 6

When did Cyanobacteria arise?

Answer 6

2.7 bya

Question 7

Why are cyanobacteria atmospheric game changers?

Answer 7

Because PHOTOSYNTHESIS

Question 8

How did Cyanobacteria arise?

Answer 8

Free O2 radicals dissolved into the seas and lakes or reacted with the Fe to yield a form of FeO; O2 was harmful to anaerobic prokaryotes.

Question 9

When was the rise of eukaryotes?

Answer 9

2 bya

Question 10

What is the difference between Eukaryotes and Prokaryotes?

Answer 10

1) NO membrane bound organelles
2) Circular DNA vs double helical DNA
3) Nucleoid present vs Nucleus

Question 11

History of Endosymbiosis

Answer 11

1905: Theory proposed by Konstantin Mereschowski referred to “symbiogensis”
1923: Ivan Waldin claims mitochondrial origin
1960’s: Lynn Margulis proposed modern-ish theory of endosymbiosis. (15 rejections)

Question 12

Early Evidence of Endosymbiosis

Answer 12

• Makes sense that a heterotrophic cell could use the nutrients produced/released from a photosynthetic cyano
• Inner membranes of mito and chloro are derived from prokaryotic decendents
• Size matches
• Genetic remnants of prokaryotic ancestor found in mito and chloro
• Plastids acquired many times independently; membrane differneces
• Organelles include equipment to transcribe and translate proteins

Question 13

Describe primary Endosymbiosis

Answer 13

A cyanobacteria phagocytized by a hetero eukaryote.

Question 14

Why after primary endosymbiosis do we only have 2 membranes?

Answer 14

Gave rise to 3; 2 from cyano and 1 from vacuole surrounding it but one was lost via enzymatic or metabolic breakdown.

Question 15

What did primary endosymbiosis give rise to?

Answer 15

Chlorophyta, Rhodophyta, and Glaucophyta. (Supergroup plantae)

Question 16

Pigments of Chlorophyta

Answer 16

Chl a and b

Question 17

Pigments of Glaucophyta

Answer 17

Chl a, phycobilin, pycocyanin

Question 18

Pigments of Rhodophyta

Answer 18

Chl a, phycoerythrin, pycocyanin, carotenoids

Question 19

2nd Endosymbioses: Green lineages

Answer 19

• Euglenophytes (3 membranes; 1 chlor E.R)
• Chlorachniphytes (4 membranes; 2 chlo E.R; Nucleomorph)
• Dinoflagellates (3 membranes; 1 chlor E.R.; uncommon)

Question 20

Pigments of Euglenophytes

Answer 20

Chl a
Chl b
Carotene
Xanthophyll

Question 21

Pigments of Chlorarchniophytes

Answer 21

Chl a

Chl b

Question 22

2nd Endosymbiosis: Red Lineage

Answer 22

• Cryptophytes (4 membranes; 2 chlo E.R.; nucleomorph)
• Haptophytes (4 membranes; 2 chlor E.R.)
• Heterokonts [Diatoms] (4 membranes; 2 chloro E.R)
• Dinoflagellates (Peridinin) (3 membranes; 1 chlor E.R; vast majority of known species)

Question 23

Pigments of Cryptophyta

Answer 23

Chl a
Chl c
Phycobillin proteins (Taken up via tertiary endo by dino)
USEFUL IN BIOFUEL HARVESTING

Question 24

Why are haptophytes important for Carbon and Sulfur cycling?

Answer 24

Cell coverings!

Question 25

Distinguishable pigment of Heterokontophyta

Answer 25

Fucoxanthin

Question 26

Defining pigment of dinophyta (red lineage)

Answer 26

Peridinin

Question 27

Tertiary Endosymbiosis

Answer 27

Red alga (euk) engulfed by protist.

Question 28

What are the 4 membranes developed by tertiary endosymbiosis?

Answer 28

• Inner/outer chloroplast membranes
• Inner chlor E.R. from plasma membrane.
• Outer chloro E.R. from food vacuole

Question 29

Chromalveolate Hypothesis

Answer 29

• 2nd endosymbiotic phagocytosis of red lineage gave rise to pigmented ancestor of Chromalveloata.
• Plastid derived proteins of dinos are all over the place (Greens!)

Question 30

Independent Acquisition Hypothesis

Answer 30

-Origin of plastids within Chromalveolates were independently derived for each division therein. Not necessarily from red algal phagocytosis. Not strong molecular evidence.