Answer to Question #103487 in Biology for Holly Williams

Question

Occasionally homologous chromosomes fail to separate during meiosis 1. Using a hypothetical example of an adult organism that has two pairs of chromosomes, describe the chromosomal makeup of the eggs that would result from this error in meiosis.

Answer 1

Meiosis consists of two division cycles. The first division is related to the separation of homologous chromosomes to two daughter cells. The second division results in the separation of two chromatids. As a result, four cells containing one chromatid are formed. If a cell contains two pairs of homologous chromosomes, the first division will result in the formation of two daughter cells containing two chromosomes. The second division will be associated with the formation of four germ cells containing two chromatids per cell. If the homologous chromosomes are not separated during the first division, the second step of meiosis will result in the formation of germ cells (i.e., eggs) containing four chromatids instead of two. As a result, the number of chromosomes in germ cells will be doubled.