Bacterial genetics

Bacterial genetics entails the study of bacterial genome and various modifications and interference to the natural bacterial genetic make-up. Bacteria have proved to be an essential part of modern genetics and have allowed researchers to understand various mechanisms that occur in human genetics, using bacteria as a model. An example of which would be an insight into how gene transcription is controlled (how genes are turned on and off/ expressed in varying levels) using the Lac Operon as a model. Bacteria used in bacterial genetics are generally haploid organisms, i.e. one copy of an allele which produces an immediate effect on a phenotype. In most cases plasmids are used to transfer genes from donor to recipient, which can replicate independently. Bacterial genetics have allowed us to gain understanding of transduction, conjugation and transformation.

Bacterial genes are carried in bacteria in 3 ways. Firstly on the bacterial chromosome, found in the nucleoid of the cell. Bacteria have only one chromosome, which is a single circle of DNA with around 4000 kbp (kilobase pairs) of DNA. Usually, all essential genes, such as genes necessary for bacterial growth are found on the chromosome. Another location for bacterial genes is the plasmid, which is found in some bacteria. The plasmid contains much less DNA than the chromosome (around 200 kbp) and is associated with a specific function, but with a usually non-essential purpose. They are circular, double-stranded DNA, and can enable drug resistance in the bacteria they are found in. Finally Transposons also carry bacterial genes, and are able to move from one location in the bacteria to another, for example between plasmids, or between the plasmid and it's bacterial cell's chromosome. They contain genes again for specialised functions for example antibiotic resistance, but do not carry genes for replication of the bacterial cell.