Question

Humans have 23 pairs of chromosome in every body cell. Even one extra chromosome causes death or serious disorders. For example, an extra copy of chromosome 21 causes Down syndrome. Down syndrome in humans is caused due to an error during a certain process. Name that process, and identify the point at which an error may take place that would cause Down syndrome.

Answer 1

Down syndrome is caused by the presence of an extra copy of chromosome 21, which occurs due to nondisjunction during meiosis. The probability of such an error increases with maternal age.

Step-by-step explanation:

Down syndrome, also known as Trisomy 21, is caused by an error during the process of meiosis. Specifically, this error is called nondisjunction, which is the failure of chromosome pairs to separate properly during meiosis. As a result, an egg or sperm may carry an extra copy of chromosome 21. If this gamete is involved in fertilization, the resulting zygote will have three copies of chromosome 21, leading to Down syndrome. This condition can lead to physical deformities, developmental delays, and mental disability. The likelihood of nondisjunction increases with maternal age, particularly in women over the age of 36.