A gene is a nucleotide base sequence in a DNA molecule that codes for the production of a specific sequence of amino acids, that in turn make up a specific polypeptide (protein)
The DNA nucleotide base code found within a gene is a triplet code
A sequence of three DNA bases, called a triplet, codes for a specific amino acid
Codon - A sequence of three bases that codes for a specific amino acid
Eg: CAG codes for the amino acid valine
Features of the Genetic Code:
Degenerate - Most amino acids are coded for by more than one triplet
Features of the Genetic Code: DEGENERATE
There are 4 bases, so there are 64 different triplets possible, yet there are only 20 amino acids
This results in multiple codons coding for the same amino acids, thus the code is said to be degenerate (this can limit the effect of mutations)
Features of the Genetic Code:
Non-overlapping - Each base in the sequence is only read once, as each codon codes only for its particular amino acid
Features of the Genetic Code: NON-OVERLAPPING
Some of the triplets of bases code for start and stop signals
These signals tell the cell where individual genes start and stop
This ensures the cell reads the DNA correctly (the code is non-overlapping)
Features of the Genetic Code:
Universal - Each triplet codes for the same amino acid in all organisms (with a few minor exceptions)
Features of the Genetic Code: UNIVERSAL
Each triplet codes for the same amino acid in all organisms
Meaning that genetic information is transferable between species
A gene occupies a fixed position, called a locus, on a particular DNA molecule
