Question

Chromosomal mutations can have a variety of effects on individuals. Down syndrome is a disorder that causes problems such as mild to moderate mental retarationn and slow or stunted development. A common form of this disorder is the result of a genetic mutation that occurs when there is an extra chromosome 21. Which type of chromosomal mutation causes this form of Down syndrome? nondisjunction inversion deletion insertion

Answer 1

Answer:

The correct answer is nondisjunction.

Explanation:

The nondisjunction of the chromosome can be defined as the failure of separation of sister chromatid during meiosis. Due to the nondisjunction during the cell division, one daughter cells gets two chromosome and other daughter cell gets none of it. In case, the daughter cell having two chromosome is fertilized by a normal gamete it can result in trisomy.

In the case of Down Syndrome, the nondisjuction of the chromosome number 21 takes place.

Answer 2

Answer:

The correct answer would be non-disjunction.

Down syndrome refers to the genetic disease caused by the non-disjunction of chromosome number 21.

Non-disjunction refers to the event in which the homologous chromosomes or sister chromatids fail to separate properly during a cell division.

In Down syndrome, the sister chromatids of chromosome 21 fail to separate properly which results in the formation of a gamete with 2 copies of chromosome 21.

When this gamete fertilizes with another gamete, it results in the formation of a zygote with 47 chromosomes, that is, 46 chromosomes + extra copy of chromosome 21.