What is a gene?
Genes are sections of DNA that contain coded information to make polypeptides. Polypeptides combine to make proteins, and the coded information is specific, so the genes code for the protein.
A gene is a sequence of DNA bases that determine a polypeptide, and a polypeptide is a sequence of amino acids.
Triplet Code -
- The triplet code is where 3 bases code for 1 amino acid
- So overall there is 64 possible sequences
- But as there is only 20 amino acids, it is believed that some amino acids need more than 1 triplet code
- The code is "degenerate" because most amino acids have more than one triplet code
Chromosomes occur in pairs, known as homologous pairs
A homologous pair is a always 2 chromosomes that determine the same genetic characteristics. This does not mean they are identical
For example, 2 chromosomes might carry information for eye colour and blood group. But it does not mean that the information codes for the same eye colour and blood group.
The diploid number of chromosomes for a human is 46
An allele is a form of a gene that is inherited by the offspring by the parents. The parents supply one allele each.