Explanation:
The genome, made up of deoxyribonucleic acid (DNA) molecules, is often referred to as the "blueprint" that contains the vital instructions to allow a cell to sustain itself. Such information, through extensive research, had been shown to be contained within specific loci of the genome known as genes. In accordance with the central dogma of molecular biology, genes are expressed in two consecutive means, namely transcription and translation respectively.
Mature mRNA, after post-transcriptional processing of pre-mRNA, is then transported out of the nucleus to the ribosome on the membrane of the rough endoplasmic reticulum, where translation occurs. The ribosome scans the mRNA strand from a 5'- to 3'-direction until it encounters the start codon, AUG. The mRNA template is decoded in consecutive groups of three ribonucleotides, called a codon. Although each codon specifies its corresponding amino acid (exception of stop codons), however, because the genetic code is highly degenerate, meaning one amino acid may be encoded by multiple codons.
Translation terminates when the ribosome encounters a stop codon on the mRNA template which is encoded by the triplets UGA, UAA, and UAG.
We can use a codon table (shown in the image) as a template to interpret the primary structure of a polypeptide of interest. The way the table is read starts from the inside of the table to its edge following the represented nitrogenous base. For example, for the codon which encodes the amino acid methionine, AUG. We start with 'A' in the lower left of the innermost circle, then proceed out with 'U' in the middle, and then the small 'G' on the edge of the table.
Following the procedure stated previously, the codons
- UCA encodes for the amino acid serine, S.
- GUC encodes for the amino acid valine, V.
- UAG encodes for the stop codon.
- AUG encodes for the amino acid methionine, M.
- CCA encodes for the amino acid proline, P.
- GGG encodes for the amino acid glycine, G.
