BIOLOGY - Genetics - What is DNA

DNA (deoxyribose nucleic acid) is extremely important. All living things have DNA, or in the case of some viruses they have RNA instead. In eukaryotes, it is found within the nucleus and is arranged into chromosomes. DNA determines the characteristics of an organism. Specific codes of DNA are called genes. DNA is made up of nucleotides. Nucleotides are repeating units, that are made up of a phosphate group, a sugar group and a nitrogen base. There are 4 nitrogen bases: adenine, guanine, cytosine and thymine. The bases pair up and the DNA twists into a double helix shape.