| A | B |
|---|
| carrier | an individual who is heterozygous for a recessive disorder |
| pedigree | a diagram that traces the inheritance of a particular trait through several generations |
| cystic fibrosis | one of the most common recessive disorders among Caucasians |
| albinism | a disorder resulting in the absence of melanin |
| Tay-Sachs disease | a disorder on chromosome 15: predominant in Jews of eastern European descent |
| Huntington's disease | a dominant genetic disorder that affects the central nervous system |
| achrondroplasia | a dominant disorder: dwarfism |
| incomplete dominance | neither allele is dominant over the other so the heterozygous phenotype is an intermediate phenotype |
| codominance | both alleles are expressed in the heterozygous condition |
| multiple alleles | more than two alleles: human blood groups |
| epistasis | one allele hides the effects of another |
| sex chromosome | chromosome that determines an individuals gender |
| autosome | 22 pairs of chromosomes |
| sex-linked trait | traits controlled by genes on the x chromosome |
| polygenic trait | arise from the interaction of multiple pairs of genes |
| sickle-cell disease | a blood disease found in people of African descent |
| dosage compensation/x compensation | one X chromosome stops working in each of the female's body cells |
| Barr bodies | the inactivated X chromosome that shows up as a darkly stained |
| hemophilia | a recessive sex-linked disorder that is characterized by delayed clotting of the blood |
| concordance rate | the percentage of identical twins who both express a given trait |
| karyotype | pairs of homologous chromosomes that are arranged in decreasing size to produce a micrograph |
| telomere | protective caps on the ends of chromosomes |
| nondisjunction | an event when sister chromatids fail to separate properly |
| trisomy | a set of three chromosomes |
| monosomy | having only one particular type of chromosome |
| Down syndrome | trisomy 21 |
| Red-green colored blindness | a recessive sex-linked trait affects about 8% of males in the U.S. |
