Flashcards in Ch 5.1 Deck (30):
What are the proteins that are regulated in DNA homologous recombination?
they accumulate when damage is present
What is the purpose of BRAC1 and BRAC2?
They release RAD51 when it is needed for repair
BRAC1 and BRAC2 are breast cancer susceptible genes
What are Holliday junctions?
intermediate in the process of two DNA helices exchanging strands
What does holliday junctions do to different sequences?
once they are cut and ligased back together different sequences are created that are different from the original
What does meiotic recombination creates?
Hybrid chromosomes are formed with genetic material from maternal and paternal chromosomes
What two proteins in yeast create double stranded breaks in recombining chromosomes?
Recombination occurs between maternal and paternal chromosomes rather than two identical duplexes
What may you have when forming two holliday junctions in meiosis recombination?
Chromosomes that are crossovers or
Chromosomes that are non crossovers
How many human recombinations are resolved as non crossovers?
few Spo11 breaks become non crossovers
What do meiotic recombinants (crossover or non crossover have on their chromosomes?
a heteroduplex region
what is a heteroduplex?
a region where there is a mixture of DNA sequences from sister chromatids
What does gametogenesis yield during meiosis?
4 gametes containing 50% maternal and 50% paternal contributions
occasionally gametes may have 3 copies of maternal and one copy paternal
What is the divergence of expected distribution of gametes from mother and father known as?
What is transpositional recombination conservative site specific ?
DNA elements that move from one place in the genome to another. THis does not require substantial homology
What is the percentage of human genes that can be traced to mobile elements (jumping genes) ?
What are mobile elements that move by the way of transposition?
What are transposase?
enzymes that act on the ends of transposons and catalyze their movement into different parts of the genome
What are the different types of transposons?
DNA- only transposons
retroviral- like retrotransposons
What are the enzymes for movement for DNA-only transposons?
What is the mode of movement for DNA-only transposons?
moves as DNA either by cut and paste or replicative ways
Where are DNA-only transposons mostly predominant in?
spread antibiotic resistance in bacteria
penicillin is not effective against many bacterial strains
What is the antibiotic resistance in bacteria mainly a result of?
transposons that carry antibiotic-inactivating genes
What does the transposase gene do?
They make transposase monomers that recognize certain DNA sequences from donor transposons and cut and paste them into new acceptor genes
What do viruses code for in transposition Mechanism for viral integration?
Integrase (virus encoded transposase)
What do retroviral like retrotransposons resemble?
retroviruses but lack proteins
where are retroviral like retrotransposons?
How do nonretroviral retrotransposons move in the genome?
only a few are mobile
Move via endonuclease and reverse transcriptase
What is the template that nonviral retrotransposons use?
What is conservative site-specific recombination?
mediates rearrangment of mobile DNA elements
What does site specific recombination?