1 Lod analysis is used to map the likely location of a gene

1.       Lod analysis is used to map the likely location of a gene that causes an inherited susceptibility to breast cancer. One marker, D17S74, has a maximum lod score of 5.98 at = 0.001, and a different marker, D17S78, has a maximumlod score of 0.95 at = 0.10. What can you conclude?

a. D17S74 is more tightly linked to the gene causing breast cancer than D17S78.

b. D17S78 is more tightly linked to the gene causing breast cancer than D17S74.

c. Neither D17S74 nor D17S78 show significant linkage with the breast cancer trait.

D17S78 is closer to the breast cancer gene than D17S74.

e. More than one of the above.

1.      What genotype ratios result in the F2 in a monohybrid cross?

1:3

9:3:3:1

1:2:1

1:1

3:1

Solution

1. LOD score stands for logrithm of Odds.LOD score of more than 3.0 indicates that the two genes are close to each other on chromosome.

odds are a thousand to one on a genetic linkage

a. D17S74 is more tightly linked to the gene causing breast cancer than D17S78.

2.F2 of genotypic ratio is 1:2:1