Question

use the space below to draw out meiotic divisions that could result in trisomy, assuming that the error occurred during meiosis i.

Answer 1

Trisomy can occur when errors happen during meiosis I, where homologous chromosomes fail to separate properly. This can result in gametes with an extra copy of a chromosome or gametes missing a chromosome. This can lead to conditions like Down syndrome.

Step-by-step explanation:

Trisomy is a condition where an individual has three copies of a particular chromosome instead of the normal two copies. This can occur due to errors in meiosis, specifically in meiosis I. During meiosis I, if homologous chromosomes fail to separate properly, it can result in gametes with an extra copy of a chromosome or gametes missing a chromosome. This can lead to the formation of a zygote with trisomy and the development of conditions such as Down syndrome.

Answer 2

Trisomy occurs due to nondisjunction during the first division of meiosis, where homologous chromosomes fail to separate and result in gametes with an abnormal number of chromosomes.

Step-by-step explanation:

An error that leads to trisomy can occur during the first division of meiosis when the homologous chromosomes fail to separate properly, a process known as nondisjunction. Normally, each homologue in the pair would migrate to a different cell, resulting in a reduction of the ploidy level. Instead, in a nondisjunction event, both homologues go to one cell, and none to the other.

As a result, two of the four gametes produced will have an abnormal number of chromosomes - one with an additional chromosome (n+1), leading to trisomy, and one with a missing chromosome (n-1). The other two gametes would have the normal chromosome number (n). This error often leads to developmental disorders, such as Down syndrome, which is caused by an extra copy of chromosome 21.