The Structure and Composition of DNA

Introduction

DNA (deoxyribonucleic acid) is the genetic material that is responsible for transmitting hereditary information from one generation to the next. It is found in the nucleus of eukaryotes and the nucleoid of prokaryotes.

Structure of DNA

DNA is a double helix, which means that it is made up of two strands of nucleotides that are twisted around each other in a spiral shape. Each nucleotide is composed of a nitrogenous base, a sugar molecule, and a phosphate group. The two strands of DNA are held together by hydrogen bonds between the nitrogenous bases. There are four different types of nitrogenous bases in DNA: adenine (A), cytosine (C), guanine (G), and thymine (T). These bases are always paired together in the same way: A always pairs with T, and C always pairs with G. The sugar molecule in DNA is called deoxyribose. Deoxyribose is a pentose sugar, which means that it has five carbon atoms. The phosphate group in DNA is a negatively charged ion. Phosphate groups are responsible for the overall negative charge of the DNA molecule.

Composition of DNA

The composition of DNA differs from one organism to another. However, all DNA is composed of the same four nitrogenous bases, the same sugar molecule, and the same phosphate group. The base composition of DNA is the percentage of each nitrogenous base in the molecule. The base composition of DNA can be used to identify different organisms. The GC content of DNA is the percentage of guanine and cytosine in the molecule. The GC content of DNA can be used to determine the stability of the molecule.