Deoxyribonucleic Acid

Molecule that carries genetic instructions

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Deoxyribonucleic acid (DNA) is a biomolecule that carries the genetic instructions used in the growth, development, functioning, and reproduction of all known living organisms and many viruses. DNA and ribonucleic acid (RNA) are nucleic acids; alongside proteins, lipids, and complex carbohydrates (polysaccharides), nucleic acids are one of the four major types of macromolecules that are essential for all known forms of life.

Structure

DNA is composed of two long polymers of simple units called nucleotides, with backbones made of sugars and phosphate groups joined by ester bonds. These two strands run in opposite directions to each other and are therefore antiparallel. Attached to each sugar is one of four types of molecules called nucleobases (informally, bases). It is the sequence of these four nucleobases along the backbone that encodes genetic information.

The four nucleobases found in DNA are adenine (A), cytosine (C), guanine (G), and thymine (T). Adenine pairs with thymine, and cytosine pairs with guanine, forming the rungs of the DNA double helix.

Function

DNA contains the instructions needed for an organism to develop, survive, and reproduce. To carry out these functions, DNA sequences must be converted into messages that can be used to produce proteins, which are the complex molecules that do most of the work in our bodies.

The process of converting DNA into proteins involves two main steps: transcription and translation. During transcription, the DNA sequence of a gene is copied into RNA. This RNA copy, called messenger RNA (mRNA), is then used to produce a protein during translation.

Replication

DNA replication is the process by which DNA makes a copy of itself during cell division. The double helix is unwound, and each strand acts as a template for the next strand. Bases are matched to synthesize the new partner strands.

History

The discovery of DNA's structure was made by James Watson and Francis Crick in 1953, with contributions from Rosalind Franklin and Maurice Wilkins. This discovery was pivotal in the field of molecular biology.

Applications

DNA is used in forensic science to identify individuals based on their unique genetic makeup. It is also used in genetic engineering to modify organisms, in gene therapy to treat diseases, and in ancestry testing to trace lineage.

Also see

• RNA
• Genetic code
• Chromosome
• Gene
• Protein synthesis