| A | B |
|---|
| alleles | contrasting trait at the same location on a chromosome |
| cross-fertilization | opposite phenotypes forced to reproduce together |
| dihybrid cross | hybrid for two traits |
| dominant traits | the traits expressed in the hybrids of the F1 generation |
| gene locus | a specific location of a DNA strand on a chromosome |
| genotype | the combination of genes for a trait (TT,Tt, or tt) |
| heterozygous | synonym for hybrid (Tt) |
| hybrid | synonym for heterozygous (Tt) |
| codominance | both alleles are expressed in hybrids (ex. Type AB blood) |
| homozygous | same genes (TT or tt) |
| phenotype | physical expression of genotype |
| polygenic inheritance | traits with more than 3 expressions (IQ, height, hair color) |
| monohybrid | cross between parents both hybrid for 1 trait |
| pedigree | family tree showing occurence of traits |
| Punnett squares | used to figure genotypic and phenotypic ratios |
| recessive trait | the trait masked in the F1 generation |
| sex-linked traits | recessive genes on the X that cause problems in males more than females |
| traits | genes that are expressed |
| self-pollination | plants that allow their own pollen to fertilize the egg |
| trait | variation of a particular inherited character |
| genetics | study of heredity |
| testcross | mating of an individual of unknown genotype but dominant phenotype with a homozygous recessive individual |
| chromosome theory of inheritance | genes are located on chromosomes and that the behavior of chromosomes during meiosis and fertilization accounts for inheritance patterns |
| genetic linkage | tendency for alleles of genes on the same chromosome to be inherited together |
| genome | complete set of an organism's genetic material |
| histone | small protein that DNA wraps around |
| trisomy 21 | results in Down syndrome |
| Down Syndrome | results from 3 21st chromosomes |
| nondisjunction | event during meiosis in which homologous chromosomes or sister chromatids fail to separate |
| duplication | change to a chromosome in which part of the chromosome is repeated |
| deletion | change to a chromosome in which a fragment of the chromosome is removed |
| inversion | change to a chromosome in which a fragment of the original chromosome is reversed |
| translocation | change to a chromosome in which a fragment of one chromosome attaches to a nonhomologous chromosome |
| carrier | individual who has one copy of the allele for a recessive disorder and does not exhibit symptoms |
| karyotype | display of a person's 46 chromosomes |
