Ch 7: patterns of inheritance

genetic trait

any inherited characteristic of an organism that can be observed or detected

invariant traits

traits that are the same in all individuals of a species

physical traits

easily observable traits

gene

a stretch of DNA affecting a genetic trait ex. tounge rolling

biochemical traits

hidden, but measurable traits ex. metabollic rate

behavioral traits

the behaviors that are not entirely the same for everyone ex. stubborness

alleles

different versions of a specific gene

mutation

any change in DNA that makes up a gene

phenotype

genes you can actually see on a living organism ex, black dog

geneotype

alleles of a living thing ex. BB

dominant

allele that is expressed when there are 2 copies of it

recessive

allele that is expressed where there are 2 identical copies of it

homozygous dominant

consists of 2 copies of dominant allele, phenotype is domianant allelea

heterozygous recessive

2 copies of recessive allele (bb)

heterozygous

1 dominant allele and one recessive (Bb)

p (parent) generation

1 parent is homozygous dominant (PP), other is homozygous recessive (pp)

f1 (1st filial) generation

result of p generation cross, offspiring are all heterozygous (Pp)

f2 (2nd fillial) generation

result of f1 generation cross, offspting are PP, Pp, or pp

probability

chance that something will happen

homozygous

2 copies of same allele

punnett square

predicts ratio of offspring

law of segregation

2 alleles are separated during meiosis and end up in different gametes (egg or sperm cells)

chromosomal theory of inheritance

genes, which carry genetic info, are located on chromosomes, and behavior of chromosomes during meiosis explains mendelian traits

mendellian traits

traits controlled by a single gene are unaffected by environmental conditions

incomplete inheritance

when either allele is able to exert its full effect

codominant

when the effect of 2 alleles equally visible in phenotype of heterozygote

complex traits

cannot be predicted by mendel’s law of inheritance

pleiotropy

when a single gene influences a # of different traits

polygenic traits

single traits controlled by more than 1 gene

epistasis

occurs when the phenotypic effect of a gene’s alleles depends on the presence of alleles for another independently inherited gene

variant trait

traits that are different among individuals

homozygous

2 of the same allele

law of independent assortment

when gametes form 2 alleles of any given gene sequence during meiosis independently of any 2 alleles of other genes, looks at 2 different traits