Serial Endosymbiosis

Question 1

When did Eukaryotes arrive

Answer 1

1.5bya

Question 2

What characteristics of cells enabled the serial endosymbiosis theory

Answer 2

-host cell was wall-less heterotroph
-flexible plasma membrane enabled phagocytosis of food particles
-breakdown of food particles within vesicles formed by plasma membrane

Question 3

Origin of mitochondria and chloroplasts as bacterial endosymbiosis, ultimately transferring _____ DNA to the _____

Answer 3

Most
HOST

Question 4

Internalization of a patch of plasma membrane with attracted DNA forms a ________

Answer 4

Primordial nucleus

Question 5

Eukaryotes developed as a result of _________ ingesting _______

Answer 5

1 prokaryote

Another prokaryote

Question 6

Precursor to chloroplast is digesting a ______

Answer 6

Cyanobacteria

Question 7

Does endosymbiosis still occur?

Answer 7

Yes

Vorticella ingests chlorella

Question 8

Serial Endosymbiosis theory

Answer 8

1. Phagocytosis of a bacterium by an archaea
2. Phagocytoses bacteria survive on nutrients from host prokaryotic cell
3. Host and symbiotic bacterium reproduce co-independently
4. Subsequent generations contain genes of the originally infested bacterium

Question 9

Primary endosymbiosis

Answer 9

Free-living Cyanobacteria incorporated into phagotrophic eukaryotic cell ——> transformed into a chloroplast

Question 10

3 groups emerged from primary endosymbiosis

Answer 10

Chlorophyta (green algae)
Glaucophyta
Rhodophyta (red algae)

Question 11

Secondary endosymbiosis

Answer 11

A eukaryote that already acquired a chloroplast via primary endosymbiosis is engulfed by a second eukaryote

Outermost membrane if the chloroplast is interpreted as a remnant of the secondary host food vascular (phagosomal membrane)

Question 12

Euglenids evolved by the ingestion of a…

How many plastid membranes?

Answer 12

Green algae

3

Question 13

Heterokonts (brown algae, chrysophytes, and diatoms) developed from ingesting …..

How many plastid membranes?

Answer 13

Secondary endosymbiosis of a red algae

4

Question 14

Most dinoflagellates have plastics of the ______ with ____ outer membranes

Answer 14

Red lineage

3

Question 15

Tertiary endosymbiosis have how many membranes

Answer 15

3 membranes

Too many membranes may be functionally unstable

Question 16

Primary endosymbiosis has how many membranes

Answer 16

2

Question 17

Secondary endosymbiosis has how many membranes

Answer 17

3-4

Question 18

Nucelomorph

Answer 18

Remnant algal nucleus

Gene transfer from plastic to engulfing cell (not all genetic material is transferred to host)

This genome lost in all algae, except chromalveolates and chlorarachiniophytes

Question 19

Chlorarachniophytes and endosymbiosis

Answer 19

Marine amoebae with plastids obtained by secondary endosymbiosis of green algal cells

Retain remnant algal nucleus (nucleomorph) obtained through secondary endosymbiosis

Question 20

Evidence of endosymbiosis

Answer 20

1. Mitochondria and chloroplasts divide by binary fission (not manufactured by nuclear genes)
2. Mitochondria and chloroplast have circular DNA
3. Mitochondrial DNA does not encode all mitochondrial proteins (endosymbiotic gene transfer)
4. Mitochondria and chloroplasts produce their own ribosomes (30s and 50s subunits instead of 40s and 60s subunits in eukaryotic cells)
5. Antibiotics that kill or inhibit bacteria inhibit protein synthesis of mitochondria and chloroplasts
6. Sequencing ribosomal RNA demonstrates that mitochondria and chloroplasts are related to bacteria

Question 21

Conditions for engulfing food

Answer 21

Flexible cell membrane: sterols

Specialized cytoskeleton (microtubules) for capturing prey

Endocytosis to evaginate the plasmalemma

Question 22

Sterols require ….

How did this help endosymbiosis

Answer 22

O2

Oxygen required for aerobic respiration
Oxygen in early atmosphere requires endosymbiosis association between ingested aerobic bacteria and anaerobic host prokaryotes

Protection from UV by ozone —-> 02 protects from UV

Question 23

Appearance of eukaryotes depended on a build up of ____ in the atmosphere by ______

Answer 23

O2

Photosynthetic Cyanobacteria