Explain when, why, and how recombination in bacteria is like crossing over in diploid cells

Question

What will be an ideal response?

Answer 1

Both bacterial recombination and crossing over during meiosis require several factors. First, both processes require nicking of DNA. In bacteria, this is when the DNA is nicked in preparation for the transfer of single-stranded DNA via conjugation. In eukaryotes, one strand of
the DNA is nicked during the formation of chiasmata. This allows for strand invasion and crossing over between homologous chromosomes.
Second, both processes use similar enzymes to mediate recombination. DNA helicases are involved in relieving torsional strain in the circular and linear chromosomes. Ligases are necessary for repairing the phosphodiester bonds within the DNA backbone that were created by the single-stranded breaks. Single-stranded binding proteins (SSBs) assist in stabilizing the otherwise unstable ssDNA and allow it to undergo processes such as replication, recombination, and transcription.
Third, both processes require pairing of homologous sequences. In bacteria, when the chromosome DNA from the donor cell is transferred to a recipient bacterium, the homologous parts of the donor and recipient DNA molecules can undergo recombination that leads to a change in the genotype of the recipient cell. In eukaryotes, proper pairing of homologous sequences is necessary for even exchange of chromosomes during crossing over. Uneven pairing of homologous sequences can result in a region of chromosome being deleted or duplicated in the resulting gametes.