MBB 222 Lecture Notes - Lecture 25: Holliday Junction, Sister Chromatids, Spo11
20 Dec 2018
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Lecture 25 part 3: recombination and recombinant dna techniques. The synthesis products are separated according to size by capillary gel electrophoresis, and laser excitation identifies the fluorescent color associated with each dna product. The dna sequence is determined by comparing the fluorescence color with the size of the fragment. Understand how pcr can be used to (i) amplify a gene or dna fragment, and (ii) add restriction enzyme cleavage sites to each end, for insertion into a vector. Mechanism of double-strand dna break repair by homologous recombination. Rad51, brca1, and brca2 proteins initiate repair by forming a presynaptic complex. The protein complex searches for a homologous duplex and invades the sister chromatid duplex. Dna synthesis occurs using the homologous template strand to fill in the gap. The two dna duplexes are resolved, and nicks are sealed by ligase. Binding of spo11 to one of the two sister chromatids leads to dna cleavage and a double-strand break.
