Genetic Mapping

Question 1

Linkage

Answer 1

Genes on the same chromosome are inherited together

Question 2

Linkage group

Answer 2

Set of linked genes

Question 3

Gene distance and recombination rates

Answer 3

The further apart 2 genes are, the more likely that there will be recombination between them

Question 4

If the progeny look like the parentals, one can conclude that…

Answer 4

There is no recombination

Question 5

Definition of map units and how to calculate them

Answer 5

Map units=% recombination

Map units= (number of recombinants/total number of progeny)*100

Question 6

Double crossover

Answer 6

Occurs when 2 chiasmata form and there is double exchange between 2 sister chromatids

Question 7

Progeny in lowest abundance result from…

Answer 7

Double crossover

Question 8

Progeny in highest abundance is…

Answer 8

Parental

Question 9

How to tell which gene in a test cross is in the middle

Answer 9

DCO tells which gene is in middle: only one that isn’t switched (odd one out)

Question 10

Calculating map units between 2 traits with double crossover

Answer 10

Map units= [(# SCO progeny for trait + # DCO progeny)/ total progeny] * 100

Question 11

Interference

Answer 11

One chiasma inhibits formation of another nearby chiasma

Question 12

Likelihood of restoring parental phenotype in double crossover

Answer 12

The farther apart 2 genes are, the greater the probability that undetected crossovers will occur

Question 13

Roughly equal number of offspring in testcross

Answer 13

No linkage of genes

Question 14

4 high numbers from 8 phenotypic classes in testcross

Answer 14

Odd trait out assorts independently and two similar traits are linked

Question 15

2 parental (high #), 4 SCO (intermediate #), and 2 DCO (low #) in testcross

Answer 15

Odd trait out is in middle and all traits are linked