AP BIOLOGY

Detailed explanation-1: -A gain or loss in the number of chromosomes from the normal 46 is called aneuploidy. A common form of aneuploidy is trisomy, or the presence of an extra chromosome in cells. “Tri-” is Greek for “three"; people with trisomy have three copies of a particular chromosome in cells instead of the normal two copies.

Detailed explanation-2: -Changes in chromosome structure can be caused by mistakes made during cell division. To make eggs and sperm, cells go through a special process called meiosis. Meiosis is complicated so it shouldn’t be surprising that cells occasionally make a mistake. The egg or sperm can end up with the wrong number of chromosomes.

Detailed explanation-3: -Aneuploidy. A genetic condition where someone has either too many or two few chromosomes is called aneuploidy (AN-yoo-ploy-dee).

Detailed explanation-4: -The most common type of chromosomal abnormality is known as aneuploidy, an abnormal chromosome number due to an extra or missing chromosome. Most people with aneuploidy have trisomy (three copies of a chromosome) instead of monosomy (single copy of a chromosome).