character
heritable feature
Ex: hair and eye color
trait
each specific variant of a character
Ex: red vs. blonde hair
true breeding
plants will produce the offspring with the same traits if they self pollinate
P Generation
true breeding parent generation
F1 Generation
1st generation of offspring
F2 Generation
generations following F1
phenotype
physical appearance
genotype
genetic makeup (Ex: Aa, AA, aa)
locus
location of allele on chromosome
law of independent assortment
each pair of alleles segregate independent of each other during gamete formation
incomplete dominance
F1 hybrids phenotype is somewhere between two parents
Ex: blue and red parents have purple offspring
codominance
two dominant alleles affect phenotype in separate ways
Ex: roan fur in cattle, speckled or spotted
multiple alleles
most genes exist in population in more than two allele forms
Ex: four phenotypes of blood come from 3 alleles attaching carbohydrates to red blood cells
Ia adds A carb
Ib adds B card
I adds neither
pleiotropy
most genes have multiple phenotypic effects
- pleiotropy alleles –> multiple symptoms of a disease
Ex: sickle cell gene has different symptoms depending on the person (pain, fever, paralysis, kidney failure)
epistasis
one gene alters the expression of another gene at a different locus
Ex: a labrador retriver fur coat
Gene A regulates Gene B/b which determines color
polygenic inheritance
two or more genes have an additive effect on a single character
Ex: human skin color
nature vs. nurture
phenotype can depend on environment
Ex: hydrangea flower color can also depend on soil acidity
pedigree analysis
family tree shows carriers of allele mutations
recessive disorder examples
cystic fibrosis, tay-sachs disease, sickle cells
dominant disorders examples
acondroplasia, Huntington’s disease
