27.2 Eukaryotic Origins Flashcards Preview

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Flashcards in 27.2 Eukaryotic Origins Deck (15)
1

what do chloroplasts in plant cells closely resemble?

certain photosynthetic bacteria, specifically cyanobacteria

2

symbiont

an organism that lives in closely evolved association with another species

3

symbiosis

close interaction between species that live together, often interdependently

4

endosymbiosis

a symbiosis in which one partner lives within the other

5

based on Merezhkovsky's hypothesis and Margulis findings, where did chloroplasts originate?

chloroplasts originated as symbiotic cyanobacteria that through time became permanently incorporated into their hosts

6

what was the deciding evidence in support of chloroplasts' being descendants of symbiotic cyanobacteria that lived within eukaryotic cells?

the DNA of chloroplasts is independent and different from nucleotides of the nuclei of photosynthetic eukaryotes but match with those of cyanobacteria

7

eukaryotes were able to acquire photosynthesis because...

they could engulf and retain cyanobacterial cells

8

what is a common symbiotic relationship in the eukaryotic domain?

symbiosis between a heterotrophic host and a photosynthetic partner

9

mitochondria also originated as endosymbiotic bacteria from...

proteobacteria

10

mitochondria/chloroplast genomes are greatly reduced compared to bacteria because:

genes from the original bacteria endosymbiont migrated to the nucleus

11

what eukaryotic organisms don't contain mitochondria?

single-celled eukaryotic organisms found in oxygen-free environments

12

many eukaryotes that lack mitochondria contain small organelles called:

hydrogenosomes that generate ATP by anaerobic processes. hydrogenosomes are basically highly altered mitochondria adapted to life in oxygen-poor environments

13

other anaerobic eukaryotes contain smaller organelles called:

mitoses that also appear to be remnant mitochondria; only has genes needed for assembling the clusters of iron and sulfur found in many proteins

14

nuclear genes in Eukarya resemble those of Archaea because:

primoridal eukaryotic host cell was closely related to Archaea

15

what are two hypotheses for the origin of the eukaryotic cell?

1. eukaryotic cells evolved from an ancestral archaeon and only later incorporated the proteobacterial cell that became a mitochondrion
2. eukaryotic cells evolved from a symbiosis between an archaeon and a proteobacterium. the proteobacterium became a mitochondrion.