Question

1. A cross between individuals with genotypes a⁺a b⁺b x aa bb produces the following progeny (this is a symbolization system that is often used in microorganisms and Drosophila: where instead of Aand athey use a⁺and a):

a⁺a b⁺b           83

a⁺a bb            21

aa b⁺b            19

aa bb              77

1. Does the evidence indicate that these two genes are linked? Explain (what do you expect if they are not linked?).

2. If so what is the map distance between aand b? (show your wok)

3. Are the alleles in the heterozygous parent in coupling or repulsion?  How can you tell?

Answer 1

cause @ 6 Yes, the number of brogeny of cross indicate genes are linked it genes are not linked and independenth assorted than ratio of desi cross progeny will be in 1:1:1!1 ratio. Mab distance *1_21+19 - ximiul / 401 (bles ad b) "(83+21 +19+77) X100% -6300)x100% = 20% ar 20 CM. Hence distance between genes a and b is 200M. Allele in heteyozygous þarent Gata btb) are in coupling Pie. dominant allele (a+, bt) are o same homologus chromosome and both recessive allele are on the (a,b) other homologus chromosome. It is because the result of cross support data). Cat bt ia b) Piono recombinant (a b] P2 and later het ] - Highest frequency in population (number)