endosymbiont hypothesis Flashcards
symbiosis is
the living together of unlike organisms
cellular endosymbiosis
is when a single cell organism lives in a host cell
who propose cellular endosymbiosis
Lynn Margulus in 1961
mechanism of cellular endosymbiosis
1) phagocytosis of prokaryote
2) host cell and endosymbiont reproduce
3) development of interdependence
how long ago did rapid O2 accumulation occur
around 2 billion
diet multicellular plant and animal
0.6 billion ya
first living cell
3.6 BYA
first photosynthetic cell
3.6-2.6 BYA
eukaryotes developed due to
uptake of specialised prokaryotes e.g. chloroplasts and mitochdonria
chloroplasts and mitochondria
inner na douter membrane
70s ribosomes
circular DNA
Import of nuclear proteins
-endogenous mem. which enlarge the surface
-not part of the cellular endomembran esystem
what are not part of the cellular
endomembrane system
Evidence that mitochondria and chloroplasts derived from prokaryotes
1) they have their own circular genome
2) they contain 70s ribosomes
-chloroplasts use the tubulin-like FtsZ for division
4) chloroplasts and cyanobacteria have thylakoid membranes
5) both surrounded by a double membrane
6 bacteria nd mitochondria share a specific membrane lipid called CARDIOLIPIN
secondary endosymbiosis
in some organism, endosymbiosis occurred twice
examples of organisms showing secondary endosymbiosis
Dinoflagellates, apicocomplexans, stramenoplies, euglenoids, chlorarachniophytes
corals
→ coral reefs are only found in clear shallow water <60m
→ corals are a symbiosis of algae and polyp
Coral polyps and zooxanthelllae form an mutualistic cellular endosymbiosis
