11.05.2013 Molecular Biology 4 Flashcards
Accurate mechanism for replication
- repair of accidental lesion
- -is required for genetic (instability/stability)
stability
(transition/transversions)substitution of a pyrimidine with a purine or vice versa.
tranversion
(transition/transversions)substitution of a pyrimidine with another pyrimidine or a purine with another purine.
transition
First level of repair during replication is ?
3’ to 5’ exonuclease activty of DNA polymerase
T/F Distortion in the DNA helix is recognized and repaired by strand-directed mismatch repair
T
Single strand breaks or nicks provide the repair signal.
-mechansims for recognizing mismatch in (e.coli/mammalian cells)
mammalian cells
Both strands are methylated (dam methylase) at A in the sequence GATC.
There is a lag in the methylation of GATC sequence in the newly synthesized strand
(e.coli/mammalian cells)
e.coli
(MutS/MutL) recognizes mismatched bases
Mut S
(MutS/MutL)scans the DNA
for a nick to determine
the newly replicated
DNA.
MutL
T/F Colon cancer phenotype has FAP stands for familial adenomatous polyposis and HNPCC stands for hereditary non-polyposis
T
(transversions/frameshift) due to addition/deletion of bases
frameshift
Cellular metabolic activity Heat Extreme pH Radiations Substances in environment --- can all case what?
structural alteration in DNA bases
(spontaneous changed/UV damage) sepurination, deamination
spontaneous changed
(spontaneous changed/UV damage) pyrimidine dimers
UV damage
(Depurination/deamination) converst C to U
damination
(Depurination/deamination) removes a purine from the nucleotide
depurination
which one of the DNA bases would not undergo deamination?
guanin/cytosine/thymine
thymine has no amino group