BIO SCI 99 Study Guide - Midterm Guide: Rad51, Reca, Chromosome
Course CodeBIO SCI 99
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Lecture 12 DNA Repair Part III
Why are mutations in DNA repair genes more serious than mutations in other types
In what type of cell must a mutation occur in order for that mutation to be passed
onto the next generation?
What are the two major systems used by the cell to repair double-stranded breaks?
What are the major similarities and differences between these two systems?
What are some factors can that influence which of these DBS repair systems gets
1.0) Homologous Recombination
What is recombination?
What enzymatic activities are required carry out the complex task of homologous
recombination? What role do SSB (RPA in eukaryotes) proteins serve in HR
What type of enzymes are RecA and Rad51?
What other cellular applications of HR machinery, in addition to repair, were
mentioned in lecture?
1.1) In DSB repair:
What is a common consequence of having defects in the machinery that carries out
homologous recombination? What effects can chromosomal rearrangements have
on the gene expression of the cell?
What are the two homologous recombination double-stranded break repair
pathways discussed in lecture? Which steps are shared between them? What
enzymatic activities carry out each of these steps? Why are the ends of the breaks
processed to 3’OH overhangs and not 5’ PO3 overhangs? Which of the two dsDNA
molecule participating in the HR reaction (one unbroken and one broken) serves as
the template for polymerizing the strand that completes the other dsDNA? Of these
two pathways, which one requires the participation of a resolvase? Of these two
pathways, which one leaves the sequence of the donor dsDNA (the one being
invaded) unchanged? What does 'gene conversion' mean? How does homologous
recombination result in gene conversion? Of these two pathways, which one can lead
to a genetic crossover between the two participating dsDNA molecules? What
determines whether this pathway results in a genetic crossover?
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