DNA recombination Flashcards
what is required for homologous recombination?
two DNA molecules must share extended regions of nearly identical nucleotide sequences
what are the 2 main functions of homologous recombinations?
1- introduction of genetic variation
2- repair of damaged DNA
when does homologous recombination occur with the highest frequency?
meiosis
hat will facilitate the formation of double strand breaks in homologous recombination?
Spo11 and Mre11 nuclease complex
what “facilitates” homologous recombination?
RecA
what will prevent recombination between poorly matched sequences?
mismatch proof-reading machinery
what is gene conversion?
loss of 1 allele and gain of another; there is always a small amount of distortion and if it is repaired, gene conversion will result
what is site specific recombination?
involves genetic exchange at particular, short, DNA sequence
what guides site specific recombination?
recombinases
what is VDJ recombination?
mode of site specific recombination, joining of V and J DNA regions during the production of immunoglobulins and TCRs in immature B/T lymphs
describe the process of VDJ recombination
VDJ recombinase is the collection of enzymes used
initial steps by RAG1 and RaG2 (recombinations activating gene)
enzymes recognize recombination signal sequence (RSS) and induce cleavage at the site
what is DNA transposition?
movement of a short DNA segment from one location to another
3 major classes of transposons
DNA transposons
retroviral transposons
non-retroviral transposons
what enzymes is used in DNA transposons?
transposase
what enzyme is used in retroviral retrotransposons?
reverse transcriptase, integrase
HIV
