lecture 7 Flashcards
does all genetics fall under mendelian theory
uhmm nooooooo
describe what protein function does - for gene inheritance
affects how it inherits, ratio and how they inherit changes
does not fit mendels law
what is pleiotropy
the property of a single gene product affecting two or more seemingly unrelated traits
describe mutations in haplosufficient genes
RECESSIVE
most loss of function is recessive
must be homozygous to see mutation
what are dominant mutations
having a single copy of the mutation produces a phenotype - disease - despite having a wild type copy of gene
describe oncogenes
many are activated by dominant mutations
can loss of function mutations be dominant
YEEEE
describe gain of function mutation
activating mutation
dont see it since helps protein gain function
name dominant mutation models
haploinsufficiency and dominant negative
Describe haploinsufficient genes
need 2 full copies of wild type to cause phenotype
describe haploinsufficiency model
2 doses = wild type
0 doses = mutant
1 dose = mutant, since inadequate
describe dominant negative model
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
describe mutations in genes coding ribosomal subunits in drosophila
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
describe p53 mutant allels in cancer
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
what is p53
transcription factor that binds dna as a homotetramer - tetramerizes = 4 proteins come together
describe incomplete or partial dominance (dose determinant)
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
what is codominance
both alleles expressed or detected
describe how blood type determined
2 alles = A, B, i
gene responsible for blood type encodes a glycosyltransferase = puts sugar molecule on another chain
describe what each blood allele does
i = no sugars added
A = will be acetyl galactosamine at end of sugar chain - present on surface of rbc
B = puts simple galactose
describe how codominance is discovered in blood types
AB = will have both sugars
uses antibody that recognizes specific structure
depends on assay
describe A vs B vs O - codominance
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
how we classify codominance is determined by what
Determined by phenotype we characterize - methods of detection or observation
what is Hb gene
encodes beta globin = subunit of hemoglobin
describe phenotype anemia example
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