Recombination Review Deck Flashcards
what is required for 2 DNA molecules to undergo homologous recombination?
they must share an extended region of nearly identical DNA
what are the 2 “uses” of homologous recombination?
genetic variation
repair of damaged DNA
what protein will enable DNA single strand to pair with homolog?
RecA protein
what formation is unique to homologous recombination?
double holliday junction
what are the 2 possible outcomes of homologous recombination?
crossing over- exchange large regions of DNA
no crossing over- only regions between holliday junctions are swapped
what is gene conversion?
gene conversion is loss of 1 allele and gain of another (not same as crossing over)
when does gene conversion occur?
when there is no crossing over, if there is repair of the small amount of distortion that occurs in the process
8 steps in homologous recombination
- homologs align
- double stranded DNA break
- RecA
- strand invasion
- strand elongation
- holliday junctions
- endonucleases cut at junctions
- crossing over or no crossing over
when does homologous recombination occur at the highest frequency?
meiosis
describe site-specific recombination
occurs at a particular DNA sequence, extensive homology not required
what enzymes guide site specific recombination?
recombinases
what are the 2 important types of site specific recombination discussed?
horizontal gene transfer- MRSA
VDJ recombination
what is VDJ recombination?
generation of antibody and T cell diversity in the immune response
what enzymes/genes are involved with VDJ recombination? 4
VDJ recombinase
recombination activating gene 1/2 (RAG1/2)
recombination signal sequence (RSS)
what is involved with DNA transposition?
short segments of mobile DNA with the capacity to move from one location to another
