exam 3 Flashcards
Transition Mutation
Purine to Purine OR Pyrimidine to Pyrimidine
Transversion Mutation
Purine to Pyrimidine or vice versa
C imino can pair with
A
A imino can pair with
C
G enol can pair with
T
T enol can pair with
G
Methylation in e. coli DNA purpose
Tells when DNA is newly made, and which strand is the old and new one
NER UvrA purpose
Scans for distortion in DNA
NER UvrB purpose
Separates strands of DNA
NER UvrC purpose
Interacts with B to cleave top strands
NER UvrD purpose
Unwinds top strands to leave hole
Homologous recombination definition
Uses a second copy of DNA to help repair and fill holes in DNA
Enzymes used in NHEJ
Ku70/80, DNA-PKcs, Artemis, Ligase IV, Cernunnos
PCR purpose
Technique to make several copies of a given DNA
Site-Specific Recombination
High frequency, requires short specific sequences
Transposition Recombination
Moderate to low frequency, requires the ends of the transposable element
Illegitimate recombination
Very low frequency, requires little or no homology
Homologous frequency
low frequency, requires extensive homology
Site-Specific Recombination Steps
Phase lambda int searches the 4.6x10^6 bp of e coli and integrates the phage genome at specifically attB, a 34 bp sequence
Transposition Steps
Transposase acts on the specific ends of the transposon and cuts the element out of the donor DNA and inserts it into the recipient DNA
RecB
has helicase and nuclease activity
RecC
assists in separation of strands and recognizes chi sites
RecD
has helicase activity
RecA filament binding steps
Binds and then interacts with other RecA’s. Coats the 3’ end of ssDNA directionally
Functions of Hom. Rec. in prokaryotes
- repair ds breaks
- restart collapsed replication forks
- exchange DNA
Functions of Hom. Rec. in eukaryotes
- repair ds breaks
- restart collapsed replication forks
- exchange DNA
Crossing Over definition
process of exchanging chromosome parts between chromosomes during meiosis (meiotic recombination)
SPO11 crossing over function
makes ds breaks