Lecture 4/7 Flashcards
When given a pathway with something next to an arrow and something above an arrow, which is the substrate, product, and enzyme?
enzyme is above the arrow, thing to left of –> is a substrate for the enzyme to give the next product, the enzyme is above the arrow and the product is to the right of the arrow
are alleles of the same gene in the same complementation group?
yes
do alleles of the same gene complement each other?
no
are different genes that give the same phenotype part of the same complementation group?
no
if one part of a pathway is mutated, what is one way to save the WT phenotype?
give the next substrate in the pathway (something further down from the mutation) in humans for metabolic diseases
what is a potential harm of giving a downstream substrate for a mutated pathway?
there can be an accumulation of upstream substances that can lead to negative effects
what do the pluses and minuses mean on a complementation test?
+ means complements, - means doesn’t complement
if things complement, are they part of the same complementation group?
no
in what direction is a complementation table read?
horizontally
is it possible for one gene to be in multiple complementation groups?
it’s infrequent but it could happen with a large deletion in repeated/clustered genes
if multiple squares (horizontally) have a -, are they complementary? are they part of the same complementation group?
they are not complementary and ARE part of the same complementation group
if multiple squares (vertically) have a -, are they complementary? are they part of the same complementation group?
a vertical read doesn’t tell us anything
if two deaf parents have mutations in the same gene, resulting in only deaf progeny, do these mutations complement? are they in the same complementation group?
they do not complement and are in the same complementation group
what are the two pigment types for hair?
brown/black and red/blond
which colors are associated with eumelanin?
brown/black
which colors are associated with pheomelanin?
red/blond
what is the pathway for blond/red hair?
ASP (agouti signaling peptide) binds to MC1R, has a little signaling, triggers phenomelanin synthesis
what is the pathway for black/brown hair?
alpha-MSH (melanocyte stimulating hormone) binds to MC1R receptor, causes lots of signaling, leads to eumelanin synthesis
if there’s a mutation on alpha-MSH making it unusable, what color hair is the result?
less eumelanin synthesis (black brown) and more pheomelanin synthesis (blond/red)
if there’s a mutation on MC1R receptor, making it unusable, what color hair is the result?
blond/red
what condition is tyrosinase gene implicated in?
albinism
will mutations in different genes in a pathway complement or be in the same complementation group?
they will complement, different complementation groups
will mutations in the same gene in a pathway complement or be in the same complementation group?
same complementation group, will not complement
are alleles of one gene considered a complementation group?
yes
Alleles that decrease MSH and MC1R activity cause which phenotype(s)?
blond/red hair
how do the alleles of the tyrosinase gene relate to the MSH and MC1R genes?
they are epistatic to (they mask) the MSH and MC1R genes
what happens in permissive conditions for a gene with a mutant allele?
enzymes are functional, mutant allele has WT functions
what happens in restrictive conditions to a gene with a mutant allele?
enzymes are non-functional, mutant phenotype shows
what are permissive/restrictive conditions for conditional lethal mutations?
mutations are only lethal under certain conditions, under some conditions proteins denature – mutant allele has defective functions and dies, while under other conditions the mutant allele has WT functions
what is penetrance?
the % of the population showing the phenotype given a specific mutation (GT)
what is complete penetrance?
every individual carrying a specific genotype will express the associated phenotype (trait or disease).
penetrance means that you can have the same genotype but a different ______________
phenotype
what does a mutation in RB1 gene cause?
retinoblastoma – one mutant copy increases risk of disease, two mutant copies gives disease
what is the dominance pattern of retinoblastoma?
one mutant copy is autosomal dominant – child usually picks up second mutation before age 5; two mutant copies is autosomal recessive
penetrance of retinoblastoma depends on what?
which allele of the gene is present. most alleles are nonsense mutations and have >95% penetrance
what is expressivity?
degree or intensity with which a phenotype is expressed with a particular GT
is penetrance always talking about the same phenotype? is expressivity?
expressivity is talking about the degrees of expression of a phenotype of a GT, while penetrance is always talking about the same phenotype
male patterned baldness is what kind of trait?
multigenic, it involves multiple pathways
MPB is associated with which receptor? what happens when females have variant copies of the receptor?
androgen; when a female has two variant copies, it causes hair thinning
MPB is caused by high levels of _____ and _____
AR and DHT
does AR signaling cause in increase or decrease in hair follicle growth for scalp and beard?
increase for beard and decrease for scalp
how does the DHT pathway work?
Binding of lots of testos/DHT ligand to a receptor signaling decreased hair follicle growth
how do mendelian genetics assume chromosomes sort?
independently, assumes genes are on different chromosomes
