Answer :
Answer: 1) G-T-L; 2) RF = 15.375mu; 3) RF = 10.125 mu; 4)RF = 25.5 mu; 5) Interference = 63.873%
Explanation: 1) To define the order of genes, we have to identify no-crossovers, single crossovers and double crossovers among the genotype numbers. Because there is a higher probability of not having crossover, the genotype with higher number will be no crossover. On the other hand, the offsprings with the lowest numbers will be double crossover. So,
- no crossover: GgLlTt and gglltt;
- double crossover: GgLltt and ggllTt;
In order for this last two to be a double crossover, comparing to the no crossover, the allele T must be in the center. Thus, the order is G-T-L.
The others are single crossovers.
2) Recombination frequency (or fraction) is a percentage of recombination an allele can have. It can also determine the distance between genes.
The recombination fraction between G and T is: RF = ([tex]\frac{P+R}{T}[/tex]) . 100
where P is the double crossover between G and T and R is the single crossover between the same genes;
Single crossover G-T = 121+116
RF₁ = [tex]\frac{9+237}{1600}[/tex] . 100 = 15.375 mu (map unit)
3) RF for T-L:
In this case, P is the double crossover between T and L and R is the single crossover between them:
Single crossover T-L = 78 + 75 = 153
RF₂ = [tex]\frac{153+9}{1600}[/tex] .100 = 10.125 mu
Note: T represents the total of individuals from the experiment, in this case T = 1600.
4) As the order of the genes is G-T-L and RF also represents the distance between genes, the recombination fraction between G and L is
RF₃ = 15.375 + 10.125 = 25.5 mu.
5) Interference value = 1 - coefficient of coincidence
Coefficient of coincidence = [tex]\frac{observed double crossover}{expecteddoublecrossovers}[/tex] . 100
- Observed double crossover = [tex]\frac{9}{1600}[/tex]·100 = 0.5625
- Expected double crossover = product of 2 single recombination value
expected double crossover = [tex]\frac{15.375.10.125}{100}[/tex] = 1.557
coefficient of coincidence = [tex]\frac{0.5625}{1.557}[/tex] . 100 = 36.127%
Interference value = 1 - 0.36127 = 0.63873
Interference value = 63.873%