Question

Compare and contrast the 3 bacterial gene transfers with DNA recombination. Explain why these are not reproduction, and why they are important to bacterial species.

Answer 1

Transformation, transduction, and conjugation are all examples of genetic recombination.

Transduction can be done via bacteriophage or phage virus

Bacteriophage Infection cycles that can led to transduction

Lytic cycle- Bacteria is taken over to produce viruses and always ends with deathof host.

Lysogenic- Viral DNA inserts itself into the genome of bacteria. Binary Fission then produces its DNA and viral DNA. This viral DNA is not destroyed and the environment can cause cues that cut itself out and then turn on viral reproduction.

Transduction by phage capsid can act as a delivery system that can convert one bacteriainto another. Only can be done if genes are homologous to each other.

Transformation is how DNA gets from dead cell to living cell. Not all bacteria can do thisform of genetic recombination though.

Dead cell lyses

Bacteria that have protein can act as csDNA pumps that take in DNA from the external environment

If the DNA taken in is homologous, it can be recombinant

If it is not the same, it will be cut up by restriction endonucleases.

Conjugation is when DNA is transferred from one bacterial cell to another. Can only occur if bacteria have F plasmid. Bacteria that have an F plasmid are considered a F+ cell.

The 1st step of Conjugation is building a Sex pilus to another cell

The sex pilus is an one-way transfer of DNA to a recipient bacteria

ssDNA from donor will move through pilus, and change recipient genetically

In order for the donor bacterium to build the sex pilus, it needs the 25 genes associated with the F plasmid.

The copy of the F plasmid is transferred to the F- cell, which then makes it an F+ cell.

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Bacterial conjugation is often regarded as the bacterial equivalent of sexual reproduction or mating, since it involves the exchange of genetic material. However, it is not sexual reproduction, since no exchange of gamete occurs. During conjugation the donor cell provides a conjugative or mobilizable genetic element that is most often a plasmid or transposon. Most conjugative plasmids have systems ensuring that the recipient cell does not already contain a similar element. The genetic information transferred is often beneficial to the recipient. Benefits may include antibiotic resistance,xenobiotic tolerance or the ability to use new metabolites.

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Importance of Gene Transfer to Bacteria.

Acquiring genes through gene transfer provides new genetic information to microorganisms, which may allow them to survive changing environments.

The major source of variation within a bacterial species is mutation. In mutations, usually only a single gene changes at any one time.

The genetic information transferred is often beneficial to the recipient. Benefits may include antibiotic resistance,xenobiotic tolerance or the ability to use new metabolites.