Molecular Mechanisms Flashcards
name for a mutation that confers a novel property on the protein without necessarily altering its normal function
- novel property mutation
name for a mutation associated with a reduction or a complete loss of one or more of the normal functions of a protein
- loss of function
importance of loss of function mutation
- most common consequence of mutation
name of inappropriate expression of a gene at an abnormal time and place
- heterochronic
- ectopic expression
structural variants of hemoglobin
- alter the globin polypeptide without affecting the rate of synthesis
thalassemias
- decreased synthesis of one or more of the globin chains
hereditary persistence of fetal hemoglobin
- impaired perinatal switch from gamma to beta globin synthesis
sickle cell disease illustrates a molecular mechanism of
- novel property mutation
genetic passing of sickle cell disease
- autosomal recessive
probability that the sibling of someone with sickle cell disease will be a carrier for that disease
- 2/3
probably of a parent transmitting an autosomal recessive gene
- 1/2
if the person has the trait, what is the probably that they are a carrier
1
the study of the distribution of alleles in population and of how the frequencies of alleles and genotypes are maintained or changed
population genetics
Hardy Weinberg Principle
p^2 + 2pq + q^2 = 1
p+q=1
what is P
- reference allele
what is Q
- alternate allele
P^2
- frequency of homozygosity for reference
2pq
- frequency of heterozygosity
q^2
- frequency of homozygosity for alternate
when we make an approximation, what is p
- around 1
- the condition is going to be so rare that not having it will almost be 1
when we make an approximation, what is 2pq
- 2q
- because we assume p = 1
if we make an approximation, what is 2pq/(p^2 + 2pq)
- 2pq
- just ignore the bottom
population size in HWE
- population is large
mating in HWE
- random mating
allele frequency in HWE
- remains constant over time
why do allele frequencies remain constant over time
- no selection for/against any genotype
- no immigration from a population with different allele frequencies
- no mutations
effects of small populations
- genetic drift
- founder (bottleneck) effect
fluctuations in the frequency of alleles resulting from chance occurrences operating in small populations
- genetic drift
nonrandom distribution of alleles among the individuals who founded particular populations
- founder (bottleneck) effect
population contains a number of subgroups that have remained genetically separate during modern times
example
- stratification
- African Americans and caucasians in the US
choice of a mate because the mate possesses some particular trait
- assortative mating
mating with someone who is related by descent
- consanguinity
non random mating examples
- stratification
- assortative mating
- consanguinity
exceptions to constant allele frequency
- mutation
- migration
genetic passing of thalassemias
- autosomal recessive
thalassemias illustrate which molecular mechanisms
- loss of function
- gene dosage
alpha thalassemias confer resistance to
- malaria
homology of alpha thalassemias
- between alpha 1 and alpha 2 genes
- but also intergenic regions
most mutations in beta thalassemias
- missense
- nonsense
- frameshift mutations
most common form of alpha thalassemias
- full deletions
more than 200 pathogenic mutations in HBB described is an example of
- allelic heterogeneity
heredity persistence of fetal hemoglobin results from
- point mutations in promoter gamma globin genes
hereditary persistence of fetal hemoglobin illustrates which principle
- heterochronic or
- ectopic gene expression
genetic inheritance of factor V Leiden
- autosomal dominant
genetic inheritance of blood groups
- codominant
factor V leiden illustrates molecular mechanism for
- gain of function
name for mechanism where normal physiology requires more than 50% of fully active gene product to prevent disease
- haploinsufficiency
haploinsufficiency refers to which phenotypes
- dominant
name for mechanism where the abnormal protein causes an abnormal phenotype by interfering with the function of the product of the normal allele
- dominant negative effect
