Essay+on+DNA+Structure

Tan Zhi Rong - green  Brandon Ng - orange Oon Ming Shen - red Ting Chang Hui 3G2 (25) - blue

DNA stands for deoxyribonucleic acid. It is a molecule that carries genetic information necessary for all cellular functions which include cell division and cell differentiation.

The basic unit of DNA is called a nucleotide. Each nucleotide is made up of a sugar called deoxyribose, a phosphate group and a nitrogen-containing base. There are 4 types of nitrogen-containing bases in DNA - adenine (A), thymine (T), cytosine (C) and guanine (G). These different bases then form different nucleotides with the phosphate group and deoxyribose sugar - adenine nucleotide, thymine nucleotide, cytosine nucleotide and guanine nucleotide. These nucleotides can then join up together by a condensation reaction through a condensation reaction between the phosphate group of on nucleotide and the hydroxyl group on carbon 3 of the sugar of the other nucleotide to form polynucleotides. Phosphodiester bonds link the nucleotides together. Two parallel polynucleotides chains will make up a DNA molecule. The 2 chains run in opposite directions. The bases of one chain are bonded to those of the opposite chain according to the rule of basic pairing.