Question

In chromosome mapping, one map unit represents:

Options

• the distance between one gene and the next on a chromosome

• 1% crossing over between two sites on a chromosome

• 1% of the length of the chromosome

• 10% crossing over between two sites on a chromosome

Answer 1

1% crossing over between two sites on a chromosome

Explanation:

In chromosome mapping, one map unit (also called a centimorgan) is defined as 1% recombination frequency, which means there is a 1% chance of crossing over occurring between two gene loci on a chromosome. This value indicates the relative distance between genes; the higher the percentage of crossing over, the farther apart the genes are located. Thus, one map unit represents 1% crossing over between two sites on a chromosome, serving as a measure of genetic distance rather than a physical distance or a fixed portion of chromosome length.