What is DNA?

Plant cell

DNA (deoxyribonucleic acid) occurs within the cells of all living things: plants, animals and microscopic organisms. In most organisms the DNA is contained within the nucleus of cells where it forms chromosomes.

Chromosomes consist of tightly coiled strands of DNA, many thousands of base-pairs long, which are found in the nucleus of all cells. Ancient DNA consists of small fragments of DNA less than 200 base-pairs long.