Spontaneous Mutations from Replication Errors snd Base Modficatons Flashcards
what should errors be detected and corrected by
DNA repair mechanisms
what are tautomers and what do they increase
the several forms bases can take
increasing mispairing in DNA replication
when a strand of DNA template loops out and gets displaced and when DNA polymerase slips/stutters what can happen
small insertions or deletions
what nucleotides might DNA polymerase miss, causing a deletion in new strand
looped-out nucleotides
how is an unpaired loop created
by an insertion of 1/more nucleotides
what might insertion/deletions lead to
frame-shift mutations
aa insertions/deletions in gene product
e.g of a hereditary disease contributed to by repeated sequence regions
Huntington disease
how may tautomeric shifts lead to permanent base pair changes + mutations
as they change molecules covalent structure, allowing hydrogen bonding with non complementary bases
what are the 2 forms of DNA base damage that are the most common cause of spontaneous mutations
depurination
deamination
what’s depurination
loss of 1 nitrogenous base in an intact double helix
what base is usually lost in depurination
purine (A/G)
what happens in deamination
amino group (in A/C) is converted to keto (cytosine - uracil, adenine - guanine)
what does deamination cause
alteration in base-pairing specifities of 2 bases in DNA replication
what chemical mutagen can cause deamination
nitrous acid (HNO2)
what by-products might DNA get damaged by
from normal cellular processes e.g normal aerobic respiration
