DNA

DNA (deoxyribonucleic acid) is the genetic information found in the nuclei of most organisms. It is arranged into structures called chromosomes. The structure of DNA was identified as being a 'double-helix' by Watson and Crick in 1953.

DNA is composed of 4 bases; the purines: Adenine (A) and Thymine (T) and the pyrimidines: Guanine (G) and Cytosine (C). These form complementary bases pairs of AT and GC. DNA also contains a phosphate group connected to a deoxyribose sugar.

Structure of DNA

DNA strands are primarily composed of three repeating units:

• Deoxyribose sugar -
• Phosphate group
• A base

The complementary base pairs in DNA interact with one another via Hydrogen Bonds:
• A-T interactions consist of 2 intermolecular Hydrogen bonds
• G-C interactions consist of 3 intermolecular Hydrogen bonds
These interactions form bridges between two DNA chains, thus creating a double stranded 'ladder' shaped structure.