FHSST Biology/Contents/Index/TCMS/Cells and genetics/DNA and chromosomes
Deoxyribonucleic Acid (DNA) contains the genetic instruction of a cell. It is a composed of nucleotides and form a winded ladder shape (double helix). Each nucleotide is composed of a phospate, sugar (deoxyribose) and a base. There are nitrogen bases which form the 'rungs' of the ladder: adenine, thymine, cytosine, guanine.