Polynucleotide

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A polynucleotide an organic polymer (many similar molecules chemically bonded to form a chain), of paramount significance in biochemistry. The basic unit is of a polynucleotide is the nucleotide, either DNA (deoxyribonucleic acid) or RNA (ribonucleic acid). The prefix poly comes from the ancient Greek πολυς (polys, many).

[edit] Sequence

Although DNA and RNA do not generally occur in the same polynucleotide, the four species of nucleotides may occur in any order in the chain. The sequence of DNA or RNA species for a given polynucleotide is the main factor determining its function in a living organism or a scientific experiment.

[edit] Polynucleotides in organisms

Polynucleotides occur naturally in all living organisms. The genome of an organism consists of complementary pairs of enormously long polynucleotides wound around each other in the form of a double helix. Polynucleotides have a variety of other roles in organisms.

[edit] Polynucleotides in scientific experiments

Polynucleotides are used in biochemical experiments such as polymerase chain reaction (PCR) or DNA sequencing. Polynucleotides are made artificially from oligonucleotides, smaller nucleotide chains with generally fewer than 30 subunits. An polymerase enzyme is used to extend the chain by adding nucleotides according to a pattern specified by the scientist.