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12 Cards in this Set
- Front
- Back
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Semi-autonomous organelles can behave in three different ways: |
1) divide 2) fuse 3) act independently |
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What are the similarities between autonomous organelles and prokaryotes (7)? |
- circular genomes - no nucleus - Prokaryotic enzymes (topoisomerase, DNA and RNA polymerase, ribosomes, tRNA) - small size - genes homologous to cyanobacteria or other prokaryotes - division proteins and mechanisms - components of outer and inner membrane |
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What conclusion does that lead to? |
- Endosymbiosis theory |
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What does the endosymbiosis theory state: |
- free-living prokaryotes engulfed by eukaryotic cell - engulfed cell and host cell retained - mutual benefit (sharing of energetic products) - leads to comparmentalisation - gene transfer to nucleus - system of protein/metabolite import/export |
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Endosymbiosis (image) |
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Evidence for the endosymbiosis theory: |
- two membranes - all the similarities between autonomous organelles and certain prokaryotes - TOC - prokaryotic export channel; - TIC?? |
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What happened to the engulfed prokaryote with time? |
- loss of prokaryotic division genes - transfer of genes to nucleus - duplication of FtsZ ring - duplication/mutation of dynamin for use with organelle - loss of most proteins for mitochondria |
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What happened to the engulfed prokaryote with time (image)? |
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What are the three types of endosymbiosis? |
- Primary - secondary - tertiary |
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The shopping bad model? |
- Plastid has a hybrid origin - at least 1 of the membranes - derived from 1 organism - BUT the protein complement = mixed origins. Majority of proteins - originated from the successful symbiont, but some - from its unsuccessfulpredecessors =>plastid was not derived from 1 endosymbiont |
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Moving genes from organelle genome to nucleus genome: |
- High amount of photosynthetic activity will cause high amounts of oxidative stress - Protect from oxidative stress by removing genes to nucleus |
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polysymbiosis |
- gradual and sequential - loss of genes to nucleus - loss of endosymbiont - eventually endosymbiont is retained |
