Repair of DNA damage

Chromosomes of a cell contain DNA. DNA consists of two polydeoxynucleotide chains twisted around one another in the form of a helix.  DNA contains the genes and hence is the genetic material of cells. A gene can be expressed as a polypeptide.  Genome is a structure which contains one or more chromosomes and it represents a single complement of the genetic information of a particular cell. Each chromosome contains a large number of genes. Replication is a process of production of exact replicas of DNA during cell division. Replication yields new DNA chains. A cell is able to synthesize a new DNA to replace a damaged DNA. This process is called repair synthesis of DNA. DNA replication rate is co-ordinated with the rate of cell division. Replication process takes place in three stages- initiation, elongation and termination. The four inhibitors of DNA replication are inhibitors of nucleotide biosynthesis, inhibitors that bind to replication proteins, inhibitors that interact with the DNA template and nucleotide analog inhibitors. Ultraviolet radiation, ionizing radiation and various chemicals may cause damage to DNA. The best method of repair of DNA damage is excision repair where the damaged portion is cut-out and replaced by a new DNA.