Polünukleotiidahel

Polünukleotiidahel, often referred to as a polynucleotide chain, is a fundamental biological polymer. It is a long chain of nucleotides, where each nucleotide consists of a nitrogenous base, a pentose sugar, and a phosphate group. The backbone of the chain is formed by phosphodiester bonds linking the 3' carbon of one sugar to the 5' carbon of the next.

There are two primary types of polynucleotide chains in biological systems: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). DNA typically exists as a double-stranded helix, with two complementary polynucleotide chains running in opposite directions. RNA, on the other hand, is usually single-stranded, although it can fold into complex three-dimensional structures.

The sequence of nitrogenous bases along a polynucleotide chain carries genetic information. In DNA, the bases are adenine (A), guanine (G), cytosine (C), and thymine (T). In RNA, thymine is replaced by uracil (U). The specific order of these bases determines the genetic code, which dictates the synthesis of proteins and other cellular functions. Polynucleotide chains are essential for life, playing critical roles in heredity, gene expression, and protein synthesis.