Symbiosis & Genome Reduction

Question 1

Genome reduction is common in _ bacteria

Answer 1

intracellular

Question 2

The minimal genome concept represents…

Answer 2

the minimal set of genes required to support a free-living organism

Question 3

Aphids maintain _cytes, specialized cells that house… such as _ sp.

Answer 3

bacteriocytes
endosymbiotic bacteria
Buchnera aphidicola

Question 4

What does Buchnera aphidicola supply for an aphid?

Answer 4

amino acids

Question 5

There is no evidence for a _ of a reduced genome, reduction appears to be a result of _ bias

Answer 5

selection

intrinsic deletion bias

Question 6

Intrinsic deletional bias is… what is the ratio of said events in prokaryotes?

Answer 6

when deletional events outnumber insertions

10:1 deletions to insertions

Question 7

M.leprae has recently discarded _ genes recently, half of which are present as _ genes

Answer 7

~2,000 genes

pseudo/partial-genes

Question 8

Endosymbionts have a consistent bias in what mutations? The most common being _ deamination. This is known as _ bias

Answer 8

G/C->A/T
cytosine deamination
AT bias

Question 9

AT bias results in a _ to AT in symbionts lacking _

Answer 9

genomic drift

repair mechanisms

Question 10

What are the features and contributions towards genome reduction?

Answer 10

1. small population sizes - accelerates fixation of deletions
2. lacking in DNA repair mechanisms (obligates)
3. deletion bias - reduced retention of dispensable genes
4. AT rich drift