Question

If recombination frequency between AB genes is 20% and BC gene is 40% and interference is 30% in the case of a double crossover then what will be coincidence under this condition?
(A)2.4
(B)8
(C)5.6
(D)0.7

Answer 1

Hint: The formula which is used for finding the coincidence in genetics is by $\text { Coefficient of Coincidence }{ = }{ 1 }{ - }{ Interference }$ . Gene interference is defined as a measure of the independence of crossovers with respect to each other.

Complete answer:
If there's a crossover at one point on a chromosome, it's likely that no crossover will occur within the nearby spot. This phenomenon is named as interference. In this, one crossover interferes with the coincident occurrence of another crossover within the same chromosome. $\text{ Coefficient of Coincidence }{ = }{ 1 }{ - }{ Interference }{ ={ 1 }- }{ 0.3 }{ = }{ 0.7 }$.

Additional Information: In genetics, the coefficient of coincidence (c.o.c.) is a measure of interference within the formation of chromosomal crossovers during meiosis. it's generally the case that, if there's a crossover at one spot on a chromosome, this decreases the likelihood of a crossover during a nearby spot. This is often called interference. Genetic linkage is the tendency of DNA sequences that are approximate on a chromosome to be inherited together during the meiosis phase of reproduction. The 2 genetic markers that are physically mostly close to one another are unlikely to be separated into different chromatids, during the crossover in chromosomes and are therefore said to be more linked to each other than markers that are far apart. In other words, the nearer two genes are on a chromosome, the lower the prospect of recombination between them, and therefore the more likely they're to be inherited together. Markers on different chromosomes are perfectly unlinked.
So, the correct answer is ‘0.7’.

Note: The typical unit of genetic linkage is that the centimorgan (cM). It was seen that a distance of one cM between two markers tells us that the markers are separated on the different chromosomes and are separated on an average of once per 100 meiotic product,, which means that once per 50 meiosis.