perimäketjun

Perimäketjun, also known as DNA or deoxyribonucleic acid, is a molecule that carries the genetic instructions for the development, functioning, growth, and reproduction of all known organisms and many viruses. It is a double helix structure composed of two polynucleotide chains. Each polynucleotide chain consists of a backbone of alternating sugar and phosphate groups, with nitrogenous bases attached to the sugar. The four nitrogenous bases in DNA are adenine (A), guanine (G), cytosine (C), and thymine (T). These bases pair specifically: A always pairs with T, and G always pairs with C. This complementary base pairing is crucial for DNA replication and information transfer.

The sequence of these bases along the DNA molecule constitutes the genetic code. Genes, segments of DNA, contain the instructions for synthesizing proteins, which perform a vast array of functions within the cell and organism. DNA is organized into chromosomes, which are located in the nucleus of eukaryotic cells. The process of copying DNA is called replication, ensuring that genetic information is accurately passed down from one generation to the next. Mutations, changes in the DNA sequence, can occur and may lead to variations in traits or diseases. The study of perimäketjun is fundamental to genetics, molecular biology, and medicine.