Definition of DNA
DNA, or deoxyribonucleic acid, is a long polymer molecule that serves as the primary carrier of genetic information in all known living organisms and many viruses. It consists of two strands forming a double helix structure, encoding the instructions for building and maintaining an organism through sequences of nucleotides.
Structure and Components of DNA
Each DNA strand is composed of four nucleotide bases: adenine (A), thymine (T), cytosine (C), and guanine (G), linked by a sugar-phosphate backbone. The bases pair specifically—A with T, and C with G—forming the rungs of the double helix ladder discovered by Watson and Crick in 1953. This structure allows DNA to replicate accurately and store vast amounts of genetic data.
DNA in Genetic Processes
In genetics, DNA's role involves transcription, where segments called genes are copied into messenger RNA (mRNA) to direct protein synthesis via translation. For example, the gene for insulin in humans codes for the protein that regulates blood sugar, illustrating how DNA sequences determine traits like eye color or disease susceptibility through protein production.
Importance of DNA in Biology
DNA is crucial for heredity, as it is passed from parents to offspring, ensuring species continuity and enabling evolution through mutations and natural selection. Its applications extend to medicine, such as genetic testing for disorders like cystic fibrosis, forensic science for identification, and biotechnology for creating genetically modified organisms to improve crop yields.