Question

Suppose no crossing-over takes place. Use step 5 (anaphase 1) to explain why meiosis will still increase genetic variation.

Answer 1

Answer and explanation;

• Meiosis is the process by which organisms produce sex cells, known as gametes. It occurs when a germ-line cell undergoes division to yield four haploid cells that have half the number of chromosome as the original cell. This process results to genetic diversity or genetic variation of a given species.

Genetic variation occurs in three ways , namely;

• Cross over
• Reduction to haploid and
• Random Chromatid Assortment

This means even without cross over genetic variation would still occur in meiosis through the other two ways.

• Reduction to haploid occurs, since each daughter cell receives only one chromosome set from each homologous pair which reduces the diploid number to haploid number. The distribution of each chromosome is random, thus a given chromosome may be distributed in either daughter cell. The resulting gametes thus has new combinations of the mother and father chromosomes which increases genetic variation.

• Random chromatid assortment occurs during meiosis II. It is a source of genetic variation because sister chromatids separate and are randomly distributed to the daughter cells, gametes.

Answer 2

Meiosis increases genetic variation due to random segregation which occurs.

In anaphase I of meiosis, the homologous pairs (one maternal and one paternal chromosome) are moved apart to opposite ends of the cell and this process occurs random. This allows the formation of gametes with different sets of homologues. In this phase sister chromatids remain attached at their centromeres (not segragated as in mitosis).