DNA Recombination

Flashcards covering key concepts of DNA Recombination

What is the role of recombination in generating genetic diversity?

Recombination generates new combinations of genes, contributing to genetic diversity; can also generate new genes.

What are the three types of recombination and how do they differ?

Homologous recombination occurs between nearly identical sequences, non-homologous between sequences with limited similarity, and illegitimate recombination involves mobile DNA elements with little sequence similarity.

Distinguish between single crossover (SXO) and double crossover (DXO) events.

SXO involves a single crossover event, while DXO involves two crossover events.

Compare inter- and intramolecular recombination.

Intermolecular recombination occurs between different DNA molecules, while intramolecular recombination occurs within the same DNA molecule.

How do horizontal and vertical resolution of Holliday junctions differ in terms of recombinant products?

Cleavage in the horizontal plane generates both recombinant and non-recombinant products, while cleavage in the vertical plane generates only recombinant products.

Explain the outcomes of biased vs. random mismatch repair.

Biased mismatch repair favors one allele over another, leading to gene conversion, while random mismatch repair corrects mismatches without preference.

Define gene conversion.

Gene conversion is the process where one allele is converted to another due to biased mismatch repair.

Identify key enzymes involved in recombination (e.g., RecA, RecBCD, RuvABC) and their functions.

RecBCD unwinds dsDNA and generates nicks, RecA facilitates strand invasion, RuvAB catalyzes branch migration, and RuvC cleaves Holliday junctions.

What are the different sources for variation in species?

Mutation, genetic material from other species, and recombination.

How do products differ in intramolecular recombination between (a) direct repeats and (b) inverted repeats?

In direct repeats, the intervening region is deleted. In inverted repeats, the intervening region is inverted.

In SXO, what happens if one of the DNA is circular?

The end product after recombination will be a single linear molecule. It will be lethal if the circular DNA is a bacterial chromosome.

Match the following recombination proteins with their function in E. coli: •RecA •RecBCD •RuvAB •RuvC •SSB •DNA Ligase

RecA: strand invasion, RecBCD: generating nicks and unwinding DNA, RuvAB: Branch migration, RuvC: cleavage of Holliday junctions, SSB: stabilizing single-stranded DNA, DNA Ligase: sealing nicks

What is the outcome of repeats after recombination has taken place?

Direct repeats leads to deletions. Inverted repeats lead to inversions.