Deoxyribonucleic acid

Deoxyribonucleic acid (DNA) is a molecule composed of two polynucleotide chains that coil around each other to form a double helix carrying genetic instructions for the development, functioning, growth and reproduction of all known 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

The DNA molecule is a double helix, with the two strands coiled around each other. Each strand is composed of a long chain of monomer units called nucleotides, which are each composed of a phosphate group, a sugar (deoxyribose), and a nitrogenous base. The four types of nitrogenous bases found in DNA are adenine (A), cytosine (C), guanine (G), and thymine (T).

Function

The main role of DNA in the cell is the long-term storage of information. It is often compared to a set of blueprints or a recipe, or a code, since it contains the instructions needed to construct other components of cells, such as proteins and RNA molecules.

Replication

DNA replication is the process by which a double-stranded DNA molecule is copied to produce two identical DNA molecules. Replication is an essential process because, whenever a cell divides, the two new daughter cells must contain the same genetic information, or DNA, as the parent cell.

Genetic Code

The genetic code is the set of rules by which information encoded in genetic material (DNA or RNA sequences) is translated into proteins (amino acid sequences) by living cells.

See Also

• Nucleic acid sequence
• Genetics
• Molecular biology
• DNA sequencing