DNA Structure

Understanding of DNA Structure

  • DNA, short for deoxyribonucleic acid, is a long coiled structure that resembles a twisted ladder or a double helix.
  • It is composed of nucleotides, which are the basic building blocks of DNA.
  • Each nucleotide consists of a sugar, a phosphate group, and a nitrogenous base.
  • There are four types of nitrogenous bases in DNA: adenine (A), thymine (T), cytosine (C), and guanine (G).

Pairing of the Nitrogenous Bases

  • In the DNA structure, adenine (A) always pairs with thymine (T), and cytosine (C) pairs with guanine (G). This is known as complementary base pairing and it is crucial for replicating DNA accurately.

The Double Helix Structure

  • The sugar and phosphate form the backbone of the DNA helix, while the bases pair up in the centre of the helix.
  • A base from one strand forms a bond with a base from the second strand, creating a base pair.
  • The base pairs are held together by hydrogen bonds.
  • The sequence of base pairs in each DNA molecule encodes the genetic instructions for the organism.

Significance of DNA Structure

  • The double helix structure of DNA allows for the replication of DNA during cell division.
  • Each strand of DNA can serve as a template for the synthesis of a new strand, ensuring that every new cell gets a complete copy of the genetic information.
  • DNA’s structure is integral to its function of carrying and accurately passing on genetic instructions to the next generation of cells.
  • Errors in DNA replication can lead to mutations, which may cause genetic disorders.
  • Some diseases, such as cystic fibrosis and sickle cell anaemia, are caused by specific mutations in DNA.
  • Understanding the structure and function of DNA has led to advances in genetic engineering and personalised medicine.