0 a set of three nucleotides that together form a unit of genetic code in a DNA or RNA molecule --
1 a group of three chemical substances in DNA that contains the information for one of the amino acids, which are necessary for making protein (= substance necessary for the body to grow) --
For a number of organisms, evidence suggests that biased codon usage reflects the action of selection to maximize translational efficiency and accuracy.
In addition, the antigen of interest is often 'codon optimised' to improve expression levels.
Therefore, major codons should be more beneficial (and therefore, fixed in the population) in highly expressed genes.
Although the number of clones was limited caused by specimen availability, the analysed codon utilization did not have a strong bias.
Nucleotide substitutions were mainly transitions and most of them occurred at the third codon.
The remaining 25% are mainly third base substitutions in codons which are silent (synonymous nucleotide substitutions).
The initial codon is indicated in bold capital letters and stop codons in bold lower-case letters.
The second difficulty is the way to define the contribution of each codon to the fitness of a genome.
