In a genetic coding system, start codon is necessary to initiate the process of mRNA translation or protein synthesis. In a genetic coding system, AUG and UGG are the only codons, which encodes a single amino acid viz. For instance, an amino acid threonine (Thr) is coded by ACU, ACC, ACA and ACG. This is what we call redundancy or degeneracy of the genetic code. By the specific pairing between the codons (mRNA) and anticodons (tRNA), a ribosome adds particular amino acid to form a polypeptide chain during translation.Īt the time of protein synthesis, a single type of amino acid can be coded by more than one codon. There is a total of 64 combinations of DNA or RNA codons. According to the genetic coding, a codon contains three letters or bases. A genetic coding system comprises a group of codons, formed primarily by the different combinations of the four bases in the RNA or DNA. It can define as the whole set of codons that translate the DNA language into 20 essential amino acids. In a polynucleotide chain, 64 codons represent specific amino acid. The codons of mRNA give us the key to translate the DNA information to build structural or functional protein. Codons are triplets of nucleotides, or we can say it comprises three bases of either RNA or DNA. It can define as the nucleotide triplets, which have a base sequence corresponding to the type of amino acid. While studying the genetic coding system, we will go through the following important terms: Codons A codon is a unit of genetic code, which is a combination of three nucleotide base. Genetic codons hold the set of information or gene sequences, by using which the living cells can translate the genetic information into functional proteins. AUG or ATG mediates the synthesis of proteins. UAA, UAG and UGA, play a significant role in the cessation of translation, whereas initiation codon, i.e. Three codons serve as termination or stop codons, and one functions as the initiation or start codon out of 64 nucleotide triplets. A triplet coding system has four different combinations of the nitrogenous bases, in which each encodes for one of the 20 essential amino acids.Ī genetic code is degenerative because of many codons code for similar amino acid. A genetic coding system has 64 sets of triplet codons, which encodes specific amino acid to form a functional protein. A genetic code can define either as the RNA or DNA codons, which are generally expressed in a pattern of triplet codons of nitrogenous bases.
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