Genes

Abstract

Genes are regions on DNA that contain the instructions for making specific proteins. In humans, genes vary in size from hundreds of DNA bases to over 3 million base pairs. From DNA to proteins, two steps are involved. Transcription is accessing the gene and reading the instructions therein in the nucleus producing as a single strand of RNA called messenger RNA (mRNA). Translation is reading the instructions on mRNA to assemble the specified proteins on the surface of ribosomes. Genetic mutations are heritable, small-scale alterations in one or more base pairs that damage DNA. Although new mutations introduce new variation, these are constantly removed from populations. Mutations can arise naturally during DNA replication or can be caused by environmental factors like chemicals or radiation. They can be harmful, neutral, or beneficial to the organism and are generally of five types: point mutations, frameshift mutations, transposons, transitions, and transversions. This chapter explores this aspect of genes.