Origins Of Life 4

Question 1

What defines a semi-autonomous organelle ?

Answer 1

1. Specific function
2. Circular DNA genome
3. Transcription/translation machinery
4. Distinct biogenesis pathway
5. Self replicates by binary fission

Question 2

Name examples of “semi autonomous” organelles ?

Answer 2

1. Mitochondria
2. Chloroplasts

Question 3

What is the endosymbiosis theory ?

Answer 3

A theory that explains the origin of mitochondria and chloroplasts as formerly free-living prokaryotes engulfed by ancestral eukaryotes, forming a mutualistic relationship and eventually becoming organelles.

Question 4

What was the original event of endosymbiosis?

Answer 4

Mitochondria

Question 5

What evidence is there for the Endosymbiosis Theory?

Answer 5

1. Double membrane and size are similar to prokaryotes
2. Circular genome
3. Complex protein import system
4. Genetic homology between organelle genes and bacterial genes

Question 6

What other organelles can be explained by the Endosymbiosis Theory?

Answer 6

Possibly: Golgi, ER, peroxisomes and nucleus
Methanogens and fermenting heterotrophs established metabolic partnerships.
Gene transfer and membrane specialisation followed