Protein biosynthesis – the major process in a living organism. Each cage contains a set of proteins including those that are inherent only in this type of cages. As all proteins collapse sooner or later, they need to be restored continuously. This process demands expenses of energy which universal source is ATP.
What is primary structure of protein
Primary structure of protein – the sequence of the amino acids connected by peptide communications, – defines all variety of functions of these macromolecules. Information on primary structure is put into the sequences of nucleotides.
That the genome and how many them in one chromosome is called
The site of DNA containing information on structure of one protein is a gene. In one chromosome hundreds of genes can be located. Chromosomes represent the chromatin threads wound on special proteins as threads on the coil (a complex of proteins with chromatin). However, during the period between cell divisions when genes function, threads of chromatin are untwisted (despiralizovana).
As amino acids are coded in DNA
Proteins are large polymeric molecules. Their monomers are amino acids. To each amino acid in molecule DNA there corresponds the sequence from three nucleotides – a triplet. In total about 20 amino acids are a part of proteins. To each of them there correspond the triplet combinations of nucleotides of DNA, and several triplets can code one amino acid. It is considered that such redundancy of the genetic code increases reliability of storage and transfer of hereditary information.
Nitrogenous bases - "bricks" of triplets
At molecule DNA there are four nitrogenous bases: adenine (A), thymine (T), guanine (G) and tsitozin (V). From them triplets are also formed. Total number of possible combinations (codons) is 4^3=64. Thus, it would be possible to code 64 amino acids, but only 20 are necessary. Therefore some different combinations also correspond to the same amino acid. For example, the coding triplets of amino acid of alanine is GCU, GCC, GCA and GCG. The random error in the third nucleotide will not influence structure of protein in any way.
What triplets are "punctuation marks"
One molecule DNA includes a set of genes. That somehow to divide them, there are triplets signaling about the beginning and the end of any given gene – "punctuation marks". These codons are UAA, UAG, UGA. When in the course of broadcasting they appear on a ribosome, synthesis of protein comes to an end.
Important properties of the genetic code
The genetic code is specific: it means that the triplet always codes the one and only amino acid, and any another. Besides, the code is universal for all live, whether it be a bacterium or the person.