NEET BIOLOGY

Detailed explanation-1: -In a karyotype, chromosomes are arranged and numbered by size, from the largest to the smallest. Karyotype is the normal nomenclature used to describe the normal or abnormal, constitutional or acquired chromosomal complement of an individual, tissue, or cell line.

Detailed explanation-2: -To observe a karyotype, cells are collected from a blood or tissue sample and stimulated to begin dividing; the chromosomes are arrested in metaphase, preserved in a fixative and applied to a slide where they are stained with a dye to visualize the distinct banding patterns of each chromosome pair.

Detailed explanation-3: -The typical human karyotype contains 22 pairs of autosomal chromosomes and one pair of sex chromosomes. The most common karyotypes for a female contain two X chromosomes and are denoted for the sex XX. Males usually have both an X and a Y chromosome, denoted for the sex XY.

Detailed explanation-4: -According to international conventions, human autosomes, or non-sex chromosomes, are numbered from 1 to 22, in descending order by size, with the exceptions of chromosomes 21 and 22, the former actually being the smallest autosome. The sex chromosomes are generally placed at the end of a karyogram.