cell genetic material damage and repair Flashcards
what is xeroderma pigmentosum
sensitivity to sunlight
risk to multiple skin cancers after exposure to UV in sunlight
1/250,000
what are mutations
permanent changes in DNA sequence
where can mutations could be in?
somatic cells or in germline
what can mutations be
chromosomal rearrangements (can alter large sequences of DNA)
4 types of chromosomal rearrangements
deletions, duplications, inversions, and translocations
what are point mutations
mutations affecting a single or few DNA base pair
mutations on normal allele
codes for a functional protein
mutations with no phenotypic effect
codes for a functional protein
loss-of-function mutation
codes for nonfunctional protein
gain-of-function mutation
codes for a protein with a new function
silent mutation
no affect on amino acid sequence
missense mutation
produces an amino acid that is different from the usual amino acid at that position
nonsense mutation
causes the premature termination of a protein
loss-of-stop mutation
original termination codon (a stop was lost), resulting in abnormal extension of a protein’s carboxyl terminus
frameshift mutation
insertion or deletion of nucleotide bases in numbers that are not multiples of three
DNA polymerase makes ______ mistake per ______ nucleotides copied
1 per 100,000
mutations can occur?
spontaneously
what are the most frequent chemical reactions known to create serious DNA damage in cells
deprivation and deamination
what does deamination lead to
transition mutations (GC to AT)
depurination leads to?
base pair deletion
what are chemical mutagens
alkylating agents
base analogs
acridines
deaminating agents
hydroxylating agents
mutations can be _______ by chemical reagents
induced
what does alkylating agents induce
transitions, transversions, frameshift and chromosome aberrations
acridine dyes (like _____) induce _______
like proflavine induce frameshift mutations
