november 3, 2008 notes from october 12 handout

b. Mismatch repair system: similar systems in bacteria, eukaryotes
i. How system works:
1. First, find mismatched bases
a. The bonds of the pairs help keep the strand in a straight line; therefore, if you have mismatched bases the strand won’t be in a straight line
2. The unmethylated strand is the one with the error (because it’s newer) so the change will occur in that particular strand
a. Endonuclease: enzyme cuts just 1 strand of dsDNA, eats swatch of ssDNA
b. It will break 1 strand on the unmethylated strand and dissolve the swatch of DNA and then DNA polymerase synthesizes new swatch (don’t need to make a primer)
c. The fragments get patched by DNA ligase
5. Protection of the bacterial chromosome from degradation
a. advantage= to be able to tell own cell’s DNA from foreign (viral) DNA
i. There is no way to differentiate own DNA from foreign DNA
b. Restriction enzymes: cut DNA into fragments at specific sequences
i. Linear DNA especially affected by restriction enzymes

Unless otherwise stated, the content of this page is licensed under Creative Commons Attribution-ShareAlike 3.0 License