Quant/Popl Genetics + Gen of Cancer (BSCI222)

allele freq =

#indivd of genotype/#indiv in population

genotype freq =

#copies of allele in pop/total # alleles in pop

random mating

neutral models assuming any two gametes combining (e.g. clam sperm and egg release)

Hardy-weinberg equilibrium

allele and genotype frequencies will be stable over time (no change)

Mendelian (Qualitative) Traits

discontinuous traits with distinct categories (e.g. red v white flowers)

Quantitative Traits

continuous traits influenced by alleles at multiple loci and environmental variation (e.g. human height)

Meristic Characteristicss

Traits that vary in whole numbers but are still quantitative (e.g., the number of pups in a litter)

Threshold Characteristics

Traits that are either present or absent but only occur when an underlying quantitative susceptibility crosses a specific measure

Phenotypic Variance (Vp) =

Va+ Vd + Vi + Ve + Vge

Quantitative Trait Loci (QTLs)

Specific chromosomal regions or domains correlated with variation in a quantitative trait

what’s common factors about cancer

loss of anchorage dependence and density dependent inhibition

tumors

masses of cells

stochastic mutation

mutations in somatic cells where one cell causes a mass of cells

mutations in gamete-producing cells are

heritable

oncogenes

mutated proto-oncogenes (‘gain-of-function’) where too much protein is transcribed

tumor suppressing genes

prevents cell cycle advancement as a ‘loss-of-function’ with hypermethylation

what does the multi-step model say about cancer

that multiple mutations are required for a cell to become cancerous

first step of cancer cell

benign (no effect), where primary tumors are formed from rapid cell division

second step of cancer cell

metastatic (effect) where the cancer cell invades other tissues and malignant tumors form

what regulated cell progression in cell cycle

checkpoints

cyclin

protein managing timing of concentration change at different checkpoints

cyclin-dependent kinases (CDK)

proteins activating proteins that progress cell cycle

genetic drift

when a small population size fluctuates in allele frequency

migration

causes flux of alleles in/out of populations, increasing genetic variance

mutation

mutations generating new alleles that slowly increase genetic variance

directional selection

selection increases frequency of one homozygous to another

disruptive selection

selection decreases heterozygotes, increasing homozygotes

stabilizing selection (over dominance)

selection against homozygotes, increasing heterozygotes

non-random mating

selecting specific mates which will bias alleles

assortative mating

preference for mates with similar traits, decreases heterozygotes - increases homozygotes (F > 0)

disassortative mating

preference for mates with different traits, increasing heterozygotes (F < 0)

random mating

no preference for mates (F = 0)

what does inbreeding do to deleterious alleles

increases homozygous for deleterious alleles

over dominance

two opposing pressures lock both alleles in stable equilibrium (malaria/sickle cell)

founder’s effect

new population from few individuals = low diversity (e.g. coconuts)

bottleneck effect

existing population reduces from disaster = diversity lost!