Perimäainekoodi

Perimäainekoodi, often translated as genetic code, is the set of rules by which information encoded in genetic material, DNA or RNA sequences, is translated into proteins by living cells. This code defines how a sequence of nucleotide bases corresponds to a sequence of amino acids. The fundamental unit of the genetic code is the codon, a triplet of nucleotides. There are 64 possible codons, formed by combinations of the four nucleotide bases: adenine (A), guanine (G), cytosine (C), and uracil (U) in RNA, or thymine (T) in DNA.

Of these 64 codons, 61 specify one of the 20 standard amino acids. The remaining three codons are stop codons, which signal the termination of protein synthesis. The genetic code is nearly universal across all known life forms, from bacteria to humans, with only minor variations observed in some organisms. This universality is strong evidence for a common ancestor of all life.

The process of translation, where the genetic code is read, involves messenger RNA (mRNA) molecules carrying the genetic information from DNA to ribosomes. Transfer RNA (tRNA) molecules, each carrying a specific amino acid, recognize codons on the mRNA through their anticodons, ensuring the correct amino acid is added to the growing polypeptide chain. The sequence of amino acids determined by the genetic code folds into a specific three-dimensional structure, forming a functional protein.