Midterm 3

Question 1

Define forward genetics.

Question 2

Define reverse genetics.

Question 3

What is the difference between forward and reverse genetics?

Question 4

How does recombination provide new material for selection?

Question 5

What are the steps by which recombination–> gene maps?

Question 6

How can two-point cross data tell whether genes are linked?

Question 7

Why is maximum recombination frequency 50%?

Question 8

Define map distance.

Question 9

Why can’t recombination frequencies be added, but map distances can?

Question 10

Under what conditions do recombination frequencies provide a good enough approximation of map distance?

Answer 10

When crossovers are RARE (<10-15)

Question 11

Why are physical distance and map distance slightly different?

Question 12

How do you compute gene orientation and map distances from 3 pt crosses?

Question 13

Define crossover interference.

Question 14

How do you compute crossover interference?

Question 15

Predict the impact of crossover interference on map distances.

Question 16

What is linkage?

Answer 16

When syntenic genes are so close together that they are unable to assort independently.

Question 17

What are syntenic genes?

Answer 17

Genes located on the same chromosome

Question 18

What does recombination do?

Answer 18

-prophase I meiosis, crossing over (exchange of genetic material between homologs) resulting in non-parental chromosomes

Question 19

What is the physical mechanism underlying recombination?

Answer 19

crossing over

Question 20

What causes linkage?

Answer 20

Close together

Question 21

What happens when multiple crossovers occur between two genes in the same meiosis?

Answer 21

implies that the alleles are further apart