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a coding unit, a set of three nucleotides (triplet) that determines the position of a particular amino acid in a polypeptide chain synthesized under the control of a gene. A codon is a unit of the genetic code by means of which all the genetic information is “recorded” in DNA and RNA molecules. Many amino acids have more than one codon (so-called degeneracy of the code). There are three codons which do not code amino acids; rather, they determine the beginning or end of the synthesis of a polypeptide chain.


The basic unit of the genetic code, comprising sequential, nonoverlapping three-nucleotide sequences in messenger ribonucleic acid, each of which is translated into one amino acid; 61 of the 64 codons code for a specific protein synthesis; the other 3 are stop codons that specify termination of the growing polypeptide or protein chain.
References in periodicals archive ?
Keywords: TP53 gene, Endometriosis, Codon 72, Pakistani population, Cell cycle.
Majority of isolates showed mutations in codon 531 are consistent with previous study from our country 19 However, contrary findings were shown in a study from Guangxi Zhuang, China showing highest mutations in codon 526 (50%) followed by 531 (35%) and in 516 (8%).
The codon usage of the 13 protein-coding genes and the base composition of 37 genes for three species were analyzed using the program MEGA 4.
4%) with absence of WT8 band and presence of MUT3 band (indicating mutation at codon S531L); 10 (1.
Polymerase chain reaction was carried out to obtain the desired DNA sequences (containing codon 12 and 13 of the K-RAS gene) using the designed primers, and the Big Dye Terminator, Applied Biosystem's buffer and water.
leprae susceptibility to rifampicin for first three cases (PAT 1, PAT 2 and PAT 3) which showed mutations at codons 424:GAA-GGA (Val-Gly) + 442:CAA CAC (Gln--His), 438: CAG--GAG (Gln-Val) + 442:CAA--CAC (Gln--His) and only at codon 442:CAA--CAC (Gln--His) respectively were performed in MFP assay.
Domestication of exogenous genes via contextualizing the codon sequences for each specific host animal has been an accepted modification for overcoming cellular defense mechanism and subsequently the gene sequestration and silencing phenomenon.
MAS-PCR assay was performed by using two outer primers (Table 1) (11) to amplify a product of 435-bp (mutated allele) in the absence of the katG315 AGC codon, and one inner reverse primer, binds at katG315 AGC second base and amplifies a product of 292-bp, (wild-type allele) in an authorized thermal cycler (Eppendorf Gradient Cycler).
As the table shows, the most common mutation in our patients was in codon 12, with substitution of Alanine instead of Glycine (GCT instead of GGT), which was present in 12% of the cases.
All known nucleotide mutations in codon 12 were screened by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).
Translocation of the 30S ribosome one codon farther along the tRNA is the function of elongation factor EF-G (EF-2 in eukaryotes) converting the ribosome to the post translation state and shifting the uncharged tRNA to the E site and the polypetidyl tRNA (the one carrying the incomplete polypeptide) to the P site.