Lecture 19

Question 1

how does duplication occur?

Answer 1

• unequal crossing over during meiosis
• replication slippage by dna polymerase
• retrotransposition of mRNa recervse transcribed into dna

Question 2

what are the possible outcomes of gene duplication?

Answer 2

• neofunctionalization
• subfunctionalization
• gene conservation
• nonfunctionalization

Question 3

what is neofunctionalization?

Answer 3

• outcome of gene duplication
• second copy of the gene (in a pair) takes on a new function

Question 4

what is subfunctionalization?

Answer 4

• possible outcome of gene duplication
• the two copies in the gene split the function

Question 5

what is gene conservation?

Answer 5

• possible outcome of gene duplication
• the two copies both continue with the same function
• woud make twice as much protein

Question 6

what is nonfunctionalization?

Answer 6

• possible outcome of gene duplication
• second copy becomes non functional
• this is how we end up with pseudogenes

Question 7

what are complex adaptations?

Answer 7

groups of co-expressed traits that together experience selection for a common function. multiple components must be expressed together for the trait to function. experiences joint selection for a common feature

Question 8

what networks are often involved in complex adaptations?

Answer 8

• regulatory networks are often involved with complex adaptations
• changes gene expression, not changes to the structure of the genes themselves

Question 9

When can novel traits arise?

Answer 9

novel traits can arise when existing genes are expressed in a new developmental context (ex. activating a genetic pathway in a new tissue)

Question 10

why do duplicated genes accumulate mutations rapidly?

Answer 10

duplicated genes accumulate mutations rapdily because they are released from purifying selection

Question 11

how can novel traits arise in terms of duplication events?

Answer 11

• many novel traits arise from a series of duplication events followed by co-option of proteins originally involved in other body functions

Question 12

what is gene recruitment?

Answer 12

refers to the co-option of genes for a totally different function as a result of mutation

Question 13

true or false: can complex adaptations evolve through a series of small steps

Answer 13

true

Question 14

what are paralogs?

Answer 14

homologous genes that arise by duplication, multiple paralogs together form a gene family