Principles of Genetics and Breeding

1.2.3.7 Activities of genes

• A gene is a unit of information which is held as a code in a discrete segment of DNA.
• This code specifies the amino acid sequence of a protein.
• The sequence information for a single gene was not continuous along the DNA, but was interspersed with pieces of non-coding sequence.
• The coding parts of a gene sequence are exons, and the non- coding parts are introns.
• Before a gene can be expressed, the DNA that encodes it has to be transcribed into RNA.
  

A gene participates in 3 major activities.

1. A gene can be replicated-genetic information can be passed from generation to generation unchanged.
2. The sequences of bases in the RNA depends directly on the sequences of bases in the gene. Most of these RNAs, in turn, serve as templates for making protein molecules. Thus, most genes are essentially blueprints for making proteins. The production of protein from a DNA blueprint is called gene expression.
   
3. A gene can accept occasional changes, or mutations.