03/06 mutations Flashcards
(93 cards)
what is ROS
oxidative radicals that can lead to oxidative damage when in overaccumulation
are ROS induced or spontaneous exclusively?
they occur naturally and spontaneously, but when under a certain mutagen, they can be induced into overaccumulation
how does ROS cause mutations
it changes the nucleotides which changes the base pairing and hydrogen bonding
if a mutation occurs by ROS and is not repaired before replication, would this affect gene expression
yes, it did not get repaired and is passed down
how does the body prevent overaccumulation of ROS
enzymes like superoxide dismutase and catalase
as well as antioxidants
if there is an increase in reactive oxygen species due to an environmental variable (high amounts of physiological stress or ingesting a toxin), then this would be considered an induced mutation
true
what is a trinucleotide repeat expansion (TRNE)
it is a sequence of 3 nucleotides that is increased from one generation to the next
what are some diseases affected by TNREs
huntingtons disease and fragile X syndrome
are TNREs spontaneous or induced
spontaneous
for a person with a TNRE disorder, the length of a trinucleotide repeat has:
increased above the critical size
if a TNRE occurs in a coding sequence, what type of expansion will occur
repeats of CAG
where can TNREs occur
within the coding sequence of a gene or in noncoding regions of genes
for a TNRE that occurs near a coding sequence, what typically occurs
a production of CpG islands
what is a CpG island
it results from a TNRE expansion that leads to the production of methylated cytosines and can lead to silencing and a reduction in gene expansion
the expansion of methylated cytosines near the promoter leads to?
silencing of the gene
what do TNRE sequences often result in
hairpins that form due to the complementarity of the repeat
if the TNRE hairpin forms before the DNA polymerase hits the sequence, what is the result
the DNA pol will slip over the hairpin and create a template that is too short
if the DNA polymerase slips off the template strand of a TNRE sequence and a hair pin forms, what is the result
an elongated sequence of the repeat
if the DNA polymerase slipped off the template at a TNRA sequence, what is the result of the repair enzymes
a expanded repeat or a repair back to its normal length
are TNRE repeat expansions always detrimental
no, they can have no affect depending on where they occur
what is a mutagen
it is a chemical or physical agent that alters DNA structure and induces mutation, it can be avoided