Adjacent segregation

Adjacent Segregation is a term used in genetics to describe a specific type of chromosome segregation that occurs during meiosis. This type of segregation is abnormal and can lead to genetic disorders.

Overview

Adjacent segregation occurs when homologous chromosomes, instead of separating normally during meiosis, segregate to the same pole. This results in an abnormal distribution of genetic material in the resulting gametes, which can lead to genetic disorders in offspring.

Mechanism

During normal meiosis, homologous chromosomes separate and move to opposite poles of the cell. This is known as disjunction. However, in adjacent segregation, this process is disrupted. Instead of separating, the homologous chromosomes move to the same pole. This results in one gamete receiving both members of the homologous pair, while the other gamete receives none. This abnormal distribution of chromosomes can lead to genetic disorders in offspring if these gametes are involved in fertilization.

Consequences

The consequences of adjacent segregation can be severe. The resulting gametes have an abnormal number of chromosomes, a condition known as aneuploidy. If these gametes are involved in fertilization, the resulting offspring can have a variety of genetic disorders. For example, Down syndrome is caused by an extra copy of chromosome 21, which can result from adjacent segregation.

Prevention

The prevention of adjacent segregation is a complex process that involves the correct functioning of several cellular mechanisms. These include the spindle assembly checkpoint, which ensures that chromosomes are properly aligned before they are separated, and the cohesin complex, which holds sister chromatids together until they are ready to be separated.

See also

• Nondisjunction
• Chromosome segregation
• Genetic disorders