GENETICS (transition) Flashcards
codon redundancy definition
when different base pair codons can make the same amino acid
aka non missense
single base mutation not change the protein sequence
bc of redundancy in the codon
first step in central dogma
transcription
second and third steps in central dogma after transcription
splicing
translation
why might someone have a mutation for a gene their parent has, but not have the condition themselves
the mutation has variable penetrance
why is NGS (next generation sequencing) better over conventional sequencing
allows sequencing of larger number of genes
what type of chromosome translocation does aCGH pick up
UNbalanced chromosome abnormalities only eg deletions and duplications (not balanced ones eg translocations)
why is aCGH better than karyotyping
higher resolution
if a mutation (base change) for neurofibromatosis is in 5% of the population, how is it classified;
definitely benign probs benign of uncertain significance probs pathogenic definitely pathogenic
definitely benign
what characteristic of cancer cells allows them to develop new characteristics
genomic instability
missense definition
a change in 1 base that causes a change in amino acid = change in protein
if aCGH picks up unbalanced chromosome translocations, what do you use to pick up balanced chromosome translocations
FISH
central dogma definition
the explanation of how genetic material flows
penetrance definition
likelihood of having disease if you have the mutation
what does 100% penetrance mean
if you have the mutation you will get the condition
what does variable expression mean
people with a condition can be affected to varying degrees
which part of the genome contains genetic material (exon or intron)
what process removes the other part
exon
splicing
what is a start codon called
promotor
is a premature stop codon pathogenic or benign
pathogenic
what type of mutation does a base insertion/deletion cause
is this pathogenic or benign
frameshift mutation
bad ! bc all amino acids change after this point = pathogenic
what is a polymorphism
variant that doesnt cause disease
if there is a mutation in an intron what does this mean
pathogenic or benign
benign bc introns are gotten rid of anyway
what is a de novo mutation
acquired during fertilization
both parents don’t have mutation or disease
does chromosome analysis pick up balanced or unbalanced translocations
balanced (technically both, but if youre looking for unbalanced just do aCGH)
which type of genetics testing is done most (ie best guess in exams)
aCGH
what is NGS (next generation sequencing) used to see
point mutations
is NGS expensive or cheap
why
expensive
large number of base pairs done
when would you use PCR over NGS for point mutations
if no family history - so you dont know which mutation it is that youre looking for, just looking for A mutation
what is a mendelian disorder in terms of penetrance and incidence
high penetrance - little environmental factors
low incidence
autosomal dominant
risk of affected child if affected parent
1 in 2
inheritance pattern of most cardiac congenital conditions eg long QT
autosomal dominant
autosomal recessive
risk of affected child if both parents carriers
1 in 4
what generational pattern occurs with autosomal recessive conditions
tends to skip generations
x linked recessive inheritance
how many copies of gene do males need to have condition
how many copies of gene do females need to have condition
males - 1
females - 2 (can be carriers)
x linked dominant inheritance
what happens to the children (give male and female example) of an affected male
male child - unaffected (gets Y from father)
female child - affected bc dominant
in mitochondrial inheritance is it every child of an affected FEMALE or MALE that will be affected
why
every child of an affected female
mitochondrial DNA = defects come from mother
what does Y linked conditions cause in males
infertility
by what mechanism does x inactivation happen
methylation
are dizygotic twins identical or non identical
how much of their genes do they share
non identical
50%
are monozygotic twins identical or non identical
how much of their genes do they share
identical (mono = 1 egg)
100%
which type of twins (monozygotic or dizygotic) are used to prove if something is purely genetic or has environmental factors
monozygotic
after clinical trials what review do new drugs need to go through
FDA review
genetic anticipation definition
when each generation develops a genetic disease at an earlier age
hereditability definition
proportion of observable differences in a trait between individuals in a population that is due to genetic differences
reasons why someone may be the first in family to present with an autosomal dominant condition (2)
de novo mutation
low penetrance - other people have gene just don’t have condition
