Question

Describe the origin of \(\mathrm{F}^{\prime}\) bacteria and merozygotes.

Short answer

Question: Describe the origin of F' bacteria and merozygotes in a step-by-step manner. Answer: F' bacteria originate from the process of aberrant excision during the integration and excision of the F plasmid into the bacterial chromosome. When the F plasmid integrates into the bacterial chromosome, it forms an Hfr cell. If the excision happens inaccurately, a portion of the bacterial chromosome can be excised along with the F plasmid, resulting in an F' plasmid. When an F' bacterium performs conjugation with an F- bacterium, it transfers the F' plasmid along with the incorporated chromosomal genes. The recipient F- cell becomes a merozygote, containing two copies of a specific region of its chromosome: one from the original F- chromosome and one from the F' plasmid, leading to partial diploidy.

Step-by-step solution

Understanding bacterial conjugation

Bacterial conjugation is a process where one bacterium transfers its genetic material to another bacterium through a direct connection between the two cells. This involves the transfer of a specific type of plasmid called the F (fertility) plasmid.

Explaining the F plasmid

The F plasmid is a circular piece of DNA found in certain bacteria, such as Escherichia coli, that carries genes necessary for bacterial conjugation. It is independent of the bacterium's main chromosome and can replicate on its own. The F plasmid also has specific genes called tra genes, which are responsible for the initiation of conjugation.

Differentiating F+, F-, and F' bacteria

Bacteria can be classified into three types based on the presence of the F plasmid: 1. F+ bacteria: These bacteria contain the complete F plasmid and can initiate conjugation with F- bacteria. 2. F- bacteria: These bacteria lack the F plasmid and can receive it from F+ bacteria through conjugation. 3. F' bacteria: These bacteria contain F' plasmids which are derived from F plasmids but have incorporated a portion of the bacterial chromosome. They can transfer the integrated genes along with the F plasmid during conjugation.

Origin of F' bacteria

F' bacteria originate from the process of aberrant excision during the integration and excision of the F plasmid into the bacterial chromosome. When the F plasmid integrates into the bacterial chromosome, it forms an Hfr (high-frequency recombination) cell. The excision of the F plasmid from the chromosome should separate the F plasmid from the chromosomal DNA. However, if the excision happens inaccurately, a portion of the bacterial chromosome can be excised along with the F plasmid, resulting in an F' plasmid.

Formation of merozygotes

When an F' bacterium performs conjugation with an F- bacterium, it transfers the F' plasmid along with the incorporated chromosomal genes. The recipient F- cell becomes a merozygote, which means it contains two copies of a specific region of its chromosome: one from the original F- chromosome and one from the F' plasmid. The presence of these two regions can lead to partial diploidy in the recipient cell and allows the study of gene interactions and regulation in bacteria.