PATHOLOGY

Detailed explanation-1: -Genes are contained in chromosomes, which are in the cell nucleus. A chromosome contains hundreds to thousands of genes. Every normal human cell contains 23 pairs of chromosomes, for a total of 46 chromosomes.

Detailed explanation-2: -(a) Genes are located in the chromosomes.

Detailed explanation-3: -Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA). Mitochondria are structures within cells that convert the energy from food into a form that cells can use.

Detailed explanation-4: -A gene is the basic physical and functional unit of heredity. Genes are made up of DNA. Some genes act as instructions to make molecules called proteins. However, many genes do not code for proteins. In humans, genes vary in size from a few hundred DNA bases to more than 2 million bases.