Part A A Genes A, B, and C are linked on a chromosome and found in the order Pre

Question

Part A A Genes A, B, and C are linked on a chromosome and found in the order Predict the frequency of a b c progeny. A-B-C. Genes A and Brecombine with a frequency of 10%, and genes B and c recombine at a frequency of 23%. For the cross a b clabc x Enter your answer to four decimal places (example 0.2356 or 0.2300). abc/abc, predict the frequency of progeny. Assume interference is zero. Submit My Answers Give Up Part B Predict the frequency of abc progeny. Enter your answer to four decimal places (example 0.2356 or 0.2300) Submit My Answers Give Up

Explanation / Answer

Cross over percentage is 10% and 23% between loci A,B and B,C, respectively.

Parents are a+b+c/abc+ and abc/abc

abc/abc produce a single type of gamete. So, it will not influence the frequency of genotype distribution in offsprings.

Parent with a+b+c/abc+ genotype produces 8 types of gametes.

a+b+c and abc+ are parental types.

a+b+c+ and abc are single crossovers (between b and c)

a+bc+ and ab+c are single crossovers (between a and b)

a+bc and ab+c+ are double crossovers

If cross over percentage is 10% and 23% between loci A,B and B,C, respectively,

then,

Frequency of double crossovers is 0.1 x 0.23 =0.023

There two types of double crossovers (i.e., a+bc and ab+c+). For each one, frequency is 0.023/2 = 0.0115

Frequency of single crossovers between A and B loci = 0.1-double crossover frequency

= 0.1-0.023 = 0.077

There two types of single crossovers between A and B loci (i.e., a+bc+ and ab+c). For each one, frequency is 0.077/2 = 0.0385

Frequency of single crossovers between B and C loci = 0.23-double crossover frequency =0.23-0.023 = 0.207

There two types of single crossovers between B and C loci (i.e., a+b+c+ and abc). For each one, frequency is 0.207/2 = 0.1035

Now we have to calculate frequency of parental.

Parentals frequency = 1-0.077-0.207-0.023 = 0.693.

There two types of parentals (i.e. a+b+c and abc+). For each one, frequency is 0.693/2 = 0.3465

So far, I have explained frequency calculations for each possible genotype. Now I am giving answers for all the questions one by one.

A:

a+b+c progeny = 0.3465

It is parental type.

B:

abc+ progeny = 0.3465

It is also parental type.

C.

a+bc+ progeny = 0.0385

It is a single crossover (between a and b).

D:

ab+c progeny = 0.0385

It is also a single crossover (between a and b).

E:

a+b+c+ = 0.1035

It is a single crossover between B and C loci

F:

abc = 0.1035

It is a single crossover between B and C loci

G:

a+bc = 0.0115

It is a double cross over.

H:

ab+c+= 0.0115

It is also a double cross over.

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