Lecture 4/7

Question 1

When given a pathway with something next to an arrow and something above an arrow, which is the substrate, product, and enzyme?

Answer 1

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

Question 2

are alleles of the same gene in the same complementation group?

Answer 2

yes

Question 3

do alleles of the same gene complement each other?

Answer 3

no

Question 4

are different genes that give the same phenotype part of the same complementation group?

Answer 4

no

Question 5

if one part of a pathway is mutated, what is one way to save the WT phenotype?

Answer 5

give the next substrate in the pathway (something further down from the mutation) in humans for metabolic diseases

Question 6

what is a potential harm of giving a downstream substrate for a mutated pathway?

Answer 6

there can be an accumulation of upstream substances that can lead to negative effects

Question 7

what do the pluses and minuses mean on a complementation test?

Answer 7

+ means complements, - means doesn’t complement

Question 8

if things complement, are they part of the same complementation group?

Answer 8

no

Question 9

in what direction is a complementation table read?

Answer 9

horizontally

Question 10

is it possible for one gene to be in multiple complementation groups?

Answer 10

it’s infrequent but it could happen with a large deletion in repeated/clustered genes

Question 11

if multiple squares (horizontally) have a -, are they complementary? are they part of the same complementation group?

Answer 11

they are not complementary and ARE part of the same complementation group

Question 12

if multiple squares (vertically) have a -, are they complementary? are they part of the same complementation group?

Answer 12

a vertical read doesn’t tell us anything

Question 13

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?

Answer 13

they do not complement and are in the same complementation group

Question 14

what are the two pigment types for hair?

Answer 14

brown/black and red/blond

Question 15

which colors are associated with eumelanin?

Answer 15

brown/black

Question 16

which colors are associated with pheomelanin?

Answer 16

red/blond

Question 17

what is the pathway for blond/red hair?

Answer 17

ASP (agouti signaling peptide) binds to MC1R, has a little signaling, triggers phenomelanin synthesis

Question 18

what is the pathway for black/brown hair?

Answer 18

alpha-MSH (melanocyte stimulating hormone) binds to MC1R receptor, causes lots of signaling, leads to eumelanin synthesis

Question 19

if there’s a mutation on alpha-MSH making it unusable, what color hair is the result?

Answer 19

less eumelanin synthesis (black brown) and more pheomelanin synthesis (blond/red)

Question 20

if there’s a mutation on MC1R receptor, making it unusable, what color hair is the result?

Answer 20

blond/red

Question 21

what condition is tyrosinase gene implicated in?

Answer 21

albinism

Question 22

will mutations in different genes in a pathway complement or be in the same complementation group?

Answer 22

they will complement, different complementation groups

Question 23

will mutations in the same gene in a pathway complement or be in the same complementation group?

Answer 23

same complementation group, will not complement

Question 24

are alleles of one gene considered a complementation group?

Answer 24

yes

Question 25

Alleles that decrease MSH and MC1R activity cause which phenotype(s)?

Answer 25

blond/red hair

Question 26

how do the alleles of the tyrosinase gene relate to the MSH and MC1R genes?

Answer 26

they are epistatic to (they mask) the MSH and MC1R genes

Question 27

what happens in permissive conditions for a gene with a mutant allele?

Answer 27

enzymes are functional, mutant allele has WT functions

Question 28

what happens in restrictive conditions to a gene with a mutant allele?

Answer 28

enzymes are non-functional, mutant phenotype shows

Question 29

what are permissive/restrictive conditions for conditional lethal mutations?

Answer 29

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

Question 30

what is penetrance?

Answer 30

the % of the population showing the phenotype given a specific mutation (GT)

Question 31

what is complete penetrance?

Answer 31

every individual carrying a specific genotype will express the associated phenotype (trait or disease).

Question 32

penetrance means that you can have the same genotype but a different ______________

Answer 32

phenotype

Question 33

what does a mutation in RB1 gene cause?

Answer 33

retinoblastoma -- one mutant copy increases risk of disease, two mutant copies gives disease

Question 34

what is the dominance pattern of retinoblastoma?

Answer 34

one mutant copy is autosomal dominant -- child usually picks up second mutation before age 5; two mutant copies is autosomal recessive

Question 35

penetrance of retinoblastoma depends on what?

Answer 35

which allele of the gene is present. most alleles are nonsense mutations and have >95% penetrance

Question 36

what is expressivity?

Answer 36

degree or intensity with which a phenotype is expressed with a particular GT

Question 37

is penetrance always talking about the same phenotype? is expressivity?

Answer 37

expressivity is talking about the degrees of expression of a phenotype of a GT, while penetrance is always talking about the same phenotype

Question 38

male patterned baldness is what kind of trait?

Answer 38

multigenic, it involves multiple pathways

Question 39

MPB is associated with which receptor? what happens when females have variant copies of the receptor?

Answer 39

androgen; when a female has two variant copies, it causes hair thinning

Question 40

MPB is caused by high levels of _____ and _____

Answer 40

AR and DHT

Question 41

does AR signaling cause in increase or decrease in hair follicle growth for scalp and beard?

Answer 41

increase for beard and decrease for scalp

Question 42

how does the DHT pathway work?

Answer 42

Binding of lots of testos/DHT ligand to a receptor  signaling  decreased hair follicle growth

Question 43

how do mendelian genetics assume chromosomes sort?

Answer 43

independently, assumes genes are on different chromosomes