lecture 7 Flashcards

1
Q

does all genetics fall under mendelian theory

A

uhmm nooooooo

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
1
Q

describe what protein function does - for gene inheritance

A

affects how it inherits, ratio and how they inherit changes
does not fit mendels law

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is pleiotropy

A

the property of a single gene product affecting two or more seemingly unrelated traits

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

describe mutations in haplosufficient genes

A

RECESSIVE
most loss of function is recessive
must be homozygous to see mutation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what are dominant mutations

A

having a single copy of the mutation produces a phenotype - disease - despite having a wild type copy of gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

describe oncogenes

A

many are activated by dominant mutations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

can loss of function mutations be dominant

A

YEEEE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

describe gain of function mutation

A

activating mutation
dont see it since helps protein gain function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

name dominant mutation models

A

haploinsufficiency and dominant negative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe haploinsufficient genes

A

need 2 full copies of wild type to cause phenotype

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

describe haploinsufficiency model

A

2 doses = wild type
0 doses = mutant
1 dose = mutant, since inadequate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

describe dominant negative model

A

protein dimerizes, 2 functional = wild type
2 mutants = mutant
1 mutant and 1 functional = mutant affects wild type, can still dimerize and will interfere with wildtype, since they physically interact

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

describe mutations in genes coding ribosomal subunits in drosophila

A

often dominant, haploinsufficient
Mutation on single copy of gene makes ribosomes = morphological defects = tend to be shorter and thicker
loss of function mutation
cells need full load ribosomes to do what they need to do

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

describe p53 mutant allels in cancer

A

function as dominant negative
mutation in the dna binding domain in one of 2 alleles = even if mutated still makes tetramer but wont bind dna, no activation of canonical p54 target genes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is p53

A

transcription factor that binds dna as a homotetramer - tetramerizes = 4 proteins come together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

describe incomplete or partial dominance (dose determinant)

A

flower colour = mutation of gene that produces pigments = both copies of enzyme needed for red pure breed
if one functional copy = not sufficient amounts of red so will be pink
red not completely dominant = looks like blending theory kinda

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is codominance

A

both alleles expressed or detected

17
Q

describe how blood type determined

A

2 alles = A, B, i
gene responsible for blood type encodes a glycosyltransferase = puts sugar molecule on another chain

18
Q

describe what each blood allele does

A

i = no sugars added
A = will be acetyl galactosamine at end of sugar chain - present on surface of rbc
B = puts simple galactose

19
Q

describe how codominance is discovered in blood types

A

AB = will have both sugars
uses antibody that recognizes specific structure
depends on assay

20
Q

describe A vs B vs O - codominance

A

A and B are dominant over O
but A and B are codominant with each other in conventional assay
coagulates = see clear phenotype of both = why they are co dominant, both expressed
could also be incomplete dominance if have sensitive assay = quantify number of sugar molecules = end up with number between A and B

21
Q

how we classify codominance is determined by what

A

Determined by phenotype we characterize - methods of detection or observation

22
Q

what is Hb gene

A

encodes beta globin = subunit of hemoglobin

23
Q

describe phenotype anemia example

A

if HbA/HbA = no anemia
if HbS/HbS = anemia
if HbA/HbS = no anemia
as long as one not affected = fine
so sickle cell= recessive
HbA = dominant to HbS

24
describe phenotype blood cell shape example
if HbA/HbA = normal shape if HbS/HbS = sickle cell shape if HbA/HbS = slight sickle cell shape HbS = incomplete dominance to HbA aa sequence affected so protein oligomerizes = polymerizes = back = causes shape
25
describe protein level analysis of blood
could consider sickle cell as codominant = if only looking at presence protein phenotype = presence of HbA and HbS at protein level proteins migrate at diff rates = see both phenotypes separately (HbA and HbS = codominant bc both alleles can be clearly discerned at protein level) if has band in middle =would be incomplete dominance depends on assay and phenotype
26
describe recessive lethal
if 2 copies = cannot have organism = will die often heterozygous for recessive lethal appear normal - since most genes are haplosufficient
27
can humans carry recessive lethal mutations
yesss we heterozygous thooo we healthy since have one healthy copy
28
describe recessive lethal mutations in diploids vs haploids
in diploids = recessive lethal mutations maintained as heterozygous in haploids = not possible since only one copy of gene
29
describe homozygous mutations causing lethality in animals - mice
either recessive or dominant mutations normal mice = dark, yellow mice = lighter coats yellow x normal = 1:1, since yellow dom, but 2 copies of dom allele = lethal so we never get it yellow x yellow = 2:1 (yellow to normal), never get YY = since lethal gene is dominant when it comes to pigmentation phenotype but recessive for viability bc animal with 2 copies of dom will die
30
describe conditional alleles
alleles depend on condition = expression of certain features or traits depends on external factors
31
describe conditional alleles - temp sensitive mutations
at lower temps = gene functions like wild type at higher temps = gene is nonfunctional and lethal Depends on conditions
32
describe conditional alleles - auxotrophs
if on minimal media and arginine = functions like wild type if on minimal media only = non functional - lethal
33
what are auxotrophs
organisms that lost the ability to synthesize certain substances required for their growth
34
describe conditional alleles temp controlled phenotypes - rabbits
black pigmentation at extremities = depends on temp, must lower tyrosine kinase = active at a lower temp = important for producing pigmentation wont show colour in middle of rabbit since can control body temp, at extremities = harder to control
35
what is variable penetrance
percentage of individuals with a given allele who exhibit the phenotype of that allele can be obvious in one person but not other since factors can contribute
36
give ex of variable penetrance
BRCA2 mutations predispose to breast, ovarian and pancreatic cancers why = environment, interacting genes, subtlety of mutant phenotype - difficult to diagnose (psychiatric disorder) = other factors contribute
37
describe incomplete penetrance and pedigrees
dom mutation gen 2 = carriers but exception to mendelian rule not penetrant so not shown but carrier, phenotype not detected or manifested in generation gen 3 = recovers it
38
describe variable expressivity
degree to which a given allele is expresses at the phenotypic level = the intensity of the phenotype
39
describe ex of variance penetrance and expressivity
neurofibromatosis type 1 = single gene mutation all affected in diff ways (diff levels of phenotype, expressivity and penetrance) = same factor affecting penetrance may be affecting expressivity among diff individuals based on assay
40
what could sick cell be also classified as
snp = yes since caused by single nt chain and prevalent in certain ethnic background