| A | B |
|---|
| homozygous | same allele for a trait |
| heterozygous | different alleles for a trait |
| allele | different version of a gene |
| dominant | allele that is always expressed if present |
| recessive | allele that is expressed only if there is no dominant allele |
| genotype | the alleles of an individual |
| phenotype | the trait controlled by one's alleles |
| Punnett square | grid used to determine likelihood of genotypes and phenotypes in offspring |
| probability | the likelihood that something will happen |
| law of segregation | a parent's two alleles separate during meiosis with gametes being equally likely to receive either one |
| law of independent assortment | the inheritance of an allele does not affect the inheritance of another one |
| monohybrid | a cross looking at just one trait |
| dihybrid | cross looking at two traits at the same time |
| incomplete dominance | neither allele is fully dominant; traits blend |
| codominance | both alleles are fully expressed at the same time |
| polygenic | a trait that is controlled by more than one gene |
| mutation | a change in a gene |
| cystic fibrosis | genetic disorder involving faulty chlorine pumps |
| sickle cell anemia | genetic disorder involving misshaped red blood cells |
| hemophilia | sex-linked genetic disorder in which blood does not clot easily |
| Down Syndrome | genetic disorder in which cells have an extra chromosome |
| pedigree | a diagram depicting the genetic history of a family |
| genetic disorder | a disease caused by abnormalities in genes or chromosomes |
| phenylketonuria | genetic disorder in which a person can't break down phenylalanine, resulting in brain damage |
