Mutations and DNA replication/repair Flashcards
how does depurination happen
bone between base and deozyribose spontaneously hydrolyzes
what is the most common deamination
spontaneous conversion of cytosine to uracil
how do you get pyrimidine dimers
UV light dimnerizes adjacent thymine bases
somatic muation
affects only the cell where the mutation happens
what happens if you have somatic muation early in embryogenesis
mosaicism
germline mutation
mutations gets passed to offspring
gene mutation
variation in nucleotide seque3nces
genomic mucations
surplus o rloss of chromosomes
chromosomal mutaitons
rearrangements, deletions, or duplications o fchromosomal regions
mutations involving chromatin
changes in methylation of DNA
what is the most common type of mutaiton
gene mutation
what are the 3 mechanisms that cause small insertions and deletions
incorrect recomination
strange slippage
intercalating agents
what happens iwth incorrect recomination
unequal crossover
where is incorrect recombination more likely to happen
loci that have repetitive DNA
where is strand slippage during replication likely to happen
areas of repetitive sequence
intercalating agents
chemical mutagens that fuck up DNA
what is a source of chromosomal and genome mutation
meiosis
prophase I
chromosomes condense and become visible
synaptonemal complex
holds together homologous chromosomes
chiasmata
sites of crossovers
metaphase
chromsomes are positioned at the equator
anaphase
chromsomes are serparted, pulled to opp. poles
process of pulling the chromsomes apart and to opposite ends of the cell
disjunction
nondisjunction
incomplete separation of chromosomes in anaphase
the frequency of nondisjunction increases with waht
maternal age
how does gene mapping work
use frequency of recombiantion between genes on teh same chromosome as an indicator of their proxiximity
3’ –> 5’ exonuclease activity of DNA polymerase delta
responsible for bulk of DNA synthsis during replication process
what happens if an incorrect nuclteotide is found by the exonuclase
it hydrolyzes the new phosphodiester bond adn the polyermase tries again for correct base pairing
what is HNPCC caused by
defects in mismatch repair system
DNA glycosylases
recognize specific types of altered base in DNA and catalyze their hydrolytic removal
nucleotide excision repair
repairs damage caused by agents that result in large changes in structure of DNA
waht casues xeroderma pigmentosum
mutation that abolism or impair function of nucletoide excision repair
symptoms of xeroderma pigmentosum
extreme sensitivity of skin to sunlight
nonhomoglous end joining
you just connect the breaks without adding back what was lost
homologous end joinging
us the recombination processes to repair broken DNA, no loss of information
how is cytarabine different from cytidine
contains arabinosine instead of ribose
what do you treat with cytarabine
acute leukemias
how does cytarbine work
turns into cytarabine triphosphate inside cells. competes with deoxyribonucleotides for binding to DNA polymerase, blocking DNA replication
what do you treat with cyclophosphamide
hodgkin’s lymphoma
how does cyclophosphamide work
acts as alkylating agents, does damage to DNA
what is doxorubicin
anthracycline antibotic
how does doxorubicin work
forms complex with DNA and toposimoerase II
how does toposiiomerase II work
passing 1 double stranged DNA seg throough a double stranged break in another double stranded DNA segment
what happens after doxorubicins binds to toposiomerase II
double stranded breaks accumulate, lead to apoptosis
