DNAsäikeet

DNAsäikeet refers to the strands of deoxyribonucleic acid. DNA is a molecule that carries the genetic instructions for the development, functioning, growth, and reproduction of all known organisms and many viruses. It consists of two long polynucleotide chains that coil around each other to form a double helix. Each polynucleotide chain is a polymer of nucleotides. A nucleotide is composed of a deoxyribose sugar, a phosphate group, and one of four nitrogenous bases: adenine (A), guanine (G), cytosine (C), and thymine (T).

The two DNA säikeet are held together by hydrogen bonds between complementary bases. Adenine always pairs with thymine (A-T), and guanine always pairs with cytosine (G-C). This complementary base pairing is crucial for DNA replication and transcription. The sequence of these bases along a DNA molecule encodes genetic information. The order of A, T, C, and G bases determines the genetic code, which dictates the sequence of amino acids in proteins and thus influences an organism's traits.

In most organisms, DNA is organized into chromosomes within the nucleus of cells. The two säikeet of the DNA double helix run in opposite directions, a property known as antiparallel orientation. One strand runs in the 5' to 3' direction, while the other runs in the 3' to 5' direction. This antiparallel nature is essential for the mechanism of DNA replication.