| A | B |
|---|
| cross | the mating of two organisms |
| law of segregation | organisms inherit two copies of each gene which are separated during gamete formation |
| allele | alternate forms of a gene |
| homozygous | an individual with two of the same allele for a gene |
| heterozygous | an individual with two different alleles for a gene |
| locus | specific position on a chromosome where a gene is located |
| genotype | the genetic makeup of a specific gene |
| phenotype | physical characteristics, or traits, of an individual organism |
| dominant | an allele that is expressed even if only 1 copy is present and masks the expression of a recessive allele |
| recessive | an allele that is only expressed when two copies are present, hidden with 1 copy |
| Punnett square | a diagram that predicts the outcome of a particular genetic cross |
| monohybrid crosses | crosses that examine the inheritance of only one specific trait |
| F1 | first filial generation (offspring of parental generation) |
| F2 | second filial generation (offspring of F1) |
| dihybrid crosses | crosses that examine the inheritance of two traits |
| law of independent assortment | allele pairs separate independently of each other during gamete formation so different traits appear to be inherited separately |
| carrier | Someone who is heterozygous for a recessive genetic disorder does not show disease symptoms but can pass on the disease-causing allele to offspring |
| sex-linked genes | genes that are located on the sex chromosomes (usually the X which contains many more genes) |
| incomplete dominance | an inheritance where the heterozygous phenotype is somewhere between the two homozygous phenotypes |
| codominance | both alleles of a gene are expressed completely, neither allele is dominant or recessive (blood types) |
| multiple allele trait | blood types have more than two alleles involved in inheritance |
| polygenic trait | traits produced by two or more genes (skin color, hair color, eye color) |
| epistasis | inheritance where one gene can interfere with the expression of other genes |
| environmental influence | phenotype can be affected by gene expression but also by the environment, which can interact with gene expression |
| gene linkage | the probability that two genes on a chromosome will be inherited together |
| autosomal disorder | a disorder that occurs in one of the 22 pairs of autosomes |
| sex-linked disorder | a disorder that occurs in the sex chromosomes, almost always in the X chromosome |
| sex-linked carrier | must be a female that carries one normal copy and one copy containing the genetic disorder that will not be expressed but can still be passed on |
| pedigree | a chart that can help trace the phenotypes and genotypes in a family to determine whether a disorder is inherited in the family |
| autosomal dominant disorder | the phenotype is expressed whether an individual is homozygous dominant or heterozygous |
| sex-linked trait | more males than females will show the sex-linked trait in their phenotype as they only need a single copy to express the trait on the X chromosome |
| karyotype | a picture of all the chromosomes in a cell |
