NEET BIOLOGY

Detailed explanation-1: -Meiotic nondisjunction leads to chromosomal disorders known as aneuploidy, where there is loss or gain of one or more chromosomes. Meiosis I nondisjunction is a more common cause of aneuploidy than meiosis II nondisjunction. Aneuploidy can be monosomy (2n-1), trisomy (2n+1), nullisomy (2n-2), disomy (n+1).

Detailed explanation-2: -Nondisjunction means that a pair of homologous chromosomes has failed to separate or segregate at anaphase so that both chromosomes of the pair pass to the same daughter cell. This probably occurs most commonly in meiosis, but it may occur in mitosis to produce a mosaic individual.

Detailed explanation-3: -Nondisjunction can occur during anaphase of mitosis, meiosis I, or meiosis II. During anaphase, sister chromatids (or homologous chromosomes for meiosis I), will separate and move to opposite poles of the cell, pulled by microtubules.

Detailed explanation-4: -Nondisjunctions, Duplications, and Deletions They are caused by nondisjunction, which occurs when pairs of homologous chromosomes or sister chromatids fail to separate during meiosis. The risk of nondisjunction increases with the age of the parents.

Detailed explanation-5: -Disorders of chromosome number include the duplication or loss of entire chromosomes, as well as changes in the number of complete sets of chromosomes. They are caused by nondisjunction, which occurs when pairs of homologous chromosomes or sister chromatids fail to separate during meiosis.