Question

Essay type question

Discuss three methods by which bacteria acquire foreign genetic materials

Answer 1

Answer: There are three ways by which bacteria transfer their genetic material.

i) Transformation.

ii) conjugation.

iii) Transduction.

i) Transformation: Transformation is form of genetic recombination in which bacteria from dead or degraded bacteria ( donar bacteria) enters another bacteria that is recipient bacteria. The experiment on transformation was first performed by Dr Fedrick Griffith in 1928. In order to receive the foreign DNA a recipient bacteria should be competent to receive the foreign DNA. Transformation has been studied in many Gram negative bacteria like Helicobacter pylori, Haemophilus influenza, Vibrio cholerae.

ii) Conjugation: Conjugation is a process by which the two bacteria transfer genetic material through direct contact. The contact is formed by a bridge like structure called conjugation tube. This conjugation tube is formed by pili. Through this contact one bacteria transfer the DNA into another bacteria. The genetic material transferred during contact provides recipient bacteria some advantage. Example: antibiotic resistance in bacteria occurs through conjgation.

iii) Transduction: Transduction is transfer of DNA from one bacteria to another through viruses. These viruses which attack bacteria are known as bacteriophages. These bacteriophages do not have there own machinery to replicate and express there genes. So they use the bacterial cell for replication and gene expression. In transduction first the bacteriophages infects the donar bacteria during this process this bacteriophages carry some part of the bacterial genome. This bacterial genome is donar DNA. Next time this bacteriophage infect new bacteria and transfer the donar DNA to this new bacteria it is recipient. This is the third way through which bacteria transfer genetic material with one another.