Genetics of bacteria
DNA molecule of chromosome of bacteria can be altered changes trait controlled by that gene trait may be transmitted if bacteria does not die.
Apart from mutation, there are four other ways that the genetic make up of bacteria is altered:
1) Phage Conversion:
Occurs when bacteriophage infects a lysogenic bacteria injects DNA into cytoplasm of bacteria
Some genetic material may be carried across from one bacterial cell to another by a bacterial virus (phage). During replication a piece of bacterial DNA is accdiently enclosed in phage particle inplace of normal phage DNA. Uncommon in nature
Recipient bacterial cell is genetically transformed by the addition of DNA fragments from another strain of bacteria – exogenous DNA is taken up from the environment transforms the cell which then expresses the new genes. Dependant on extensive DNA homology. Very uncommon in nature. Mediated by the gene, recA.
Two bacteria attach to each other and some genetic material is transferred from the ‘donor’ to the recipient’.
Genetic basis of resistance to antibiotics:
Resistance to antibiotics can be:
• acquired (natural insensitivity to the drug resistance)
• intrinsic (appearance of resistance to a drug in a previously sensitive population)
Random spontaneous mutations occur continuously at a low incidence some of these will infer resistance to an antibiotic.