Question

One centiMorgan is equal to recombination frequency of
A. 1
B. 0.1
C. 10
D. 0.01

Answer 1

Hint: Centimorgan was named in honor of T.H. Morgan, who received a Nobel prize for his studies on the role of chromosome in heredity. CentiMorgan (cM) is a unit to measure distance between genes on the chromosome. It's denoted by a map unit.

Complete answer:
Centimorgan is also a unit of measure of the genetic recombination frequency. The homologous recombination events can occur at any point within the DNA sequence and the genetic distances reflect physical distances.
If two loci are 1 cM apart, then a crossover occurs between them at a mean of 1 in 100 meiosis. Therefore, cM could also be a measure of the genetic or linkage distance between two loci. One map unit is adequate to 1 cM and 1 cM is up to 1% recombination. Thus, two genes that recombine with a frequency of three.5% bare said to be located 3.5 map units apart. In humans, 1 cM is roughly like 1 × 106 base pairs.
The centiMorgan (cM) values for DNA segments are measurements of how likely the segment is to recombine since it passes from parents to an offspring. Segments with higher cM values have a greater probability of recombining in any generation.
The frequency of crossover events expressed in centiMorgan cannot be correlated with the physical distance between the markers employed. The space between loci represents the frequency of occurrence of recombination and doesn’t resemble a particular physical distance. However, approximations for the worth of percentage recombination and also the number of base pairs of DNA are deduced by correlating physical chromosome maps with genetic maps.

Hence, the correct answer is option (D).

Note: The recombination rates vary among the individuals and chromosomes. CentiMorgan length also varies across the position on the identical chromosome. Because it was seen in Anopheles gambiae, the recombination rate varies from >7 cM/Mb at the telomeric end of the X chromosome to ∼0.2 cM/Mb at the centromeric end. Rate of recombination varies among individuals like in Drosophila recombination rate is 1.5 cM/Mb while in humans, it is 1.1 cM/Mb.