a Show the inferred chromosomal constitutions of the parents

a. Show the inferred chromosomal constitutions of the parents.

b. What is the map distance between the seed color gene (A) and the endosperm gene (B) in this new cross? Show the linkage arrangement of the endosperm shape and seed color alleles on the involved homologous chromosom pair in the F1, the tester strain, and the F2 as part of your answer. Indicate which of the F2 are parental and which are recombinant.

Problem 6 Cross 1: In corn, the gene for colored (A) seeds is completely dominant to the gene for colorless (a) seeds. Similarly a single gene pair controls whether the endosperm (the part of the seed that contains the food stored for the embryo) is full or shrunken. Full (B) is dominant to shrunken (b).

1. Map units are measure of tendency of cross over to occur between two loci.

2. If genes are farther apart will have higher likelihood of crossover, the higher the crossover frequency.

3. The test cross data allows indirectly to measure the frequency of gamates made by an individual.

4. All of the test cross progeny inherited a gamete with recessive \'a\' and \'b\' colourless shrunken parent.

5. So the alleles of the F1 dihybrid parent have passed on trait in the seed.

Parents Colored shrunken (AAbb) X Colorless full (aaBB)

Gamets Ab aB

F1 generation Colored full (AaBb)

If F1 crossed with Colorless shrunken(tester strian), F2 generation we got the above data.

In the above data Colored full : 920

Colored shrunken : 15,800

Colorless full : 16,000

Colorless shrunken : 900 Total are: 33,620

Colored full and colorless shrunken are parental type, Colored shrunken and Colorless full are recombinant type.

Recombination frequency= recombinant types/Total no. of progeny*100

Recombinant types are colored full 920+ colorless shrunken 900 = 1820

Recombination frequency= 1820/33620 = 0.0541X100 = 5.41mu.

a. Show the inferred chromosomal constitutions of the parents. b. What is the map distance between the seed color gene (A) and the endosperm gene (B) in this n

a Show the inferred chromosomal constitutions of the parents

Solution

Get Help Now

Submit a Take Down Notice