| A | B |
|---|
| Law of Dominance | When an organism is hybrid for a pair of contrasting traits, only the dominant trait can be seen in the hybrid. |
| Law of Segregation | factors (genes) that occur in pairs are separated from each other during meiosis and recombined at fertilization |
| chromosomes | genes are found on these structures |
| gene | a sequence of nucleotides in DNA that codes for a particular protein |
| alleles | different forms of the same gene (ex: T or t) |
| homozygous | containing two alleles that are the same (ex: tt or TT) |
| heterozygous | containing two alleles that are different (ex: Tt) |
| genotype | the genetic makeup of an organism (ex: Tt) |
| phenotype | the physical trait that an organism develops as a result of its genotype (ex: tall) |
| Law of Independent Assortment | During meiosis, genes for different traits are separated and distributed to gametes independently of one another |
| incomplete dominance | occurs when two alleles contribute to the phenotype;traits blend |
| codominance | both traits are expressed at the same time |
| multiple alleles | more than two alleles for the same trait (ex:blood type in humans) |
| genotype of a male | XY |
| genotype of a female | XX |
| sex chromosomes | chromosomes that determine the sex of an organism |
| sex-linked traits | traits that are controlled by genes on the sex chromosomes (usually the X) |
| examples of sex-linked traits in humans | hemophilia, color-blindness |
| multiple-gene or polygenic inheritance | when two or more independent genes affect one trait |
| karyotype | a chart showing all of an organism's chromosomes, arranged in homologous pairs |
| amniocentesis | removal of amniotic fluid surrounding fetus, used to test for genetic diseases |
| chorionic villus sampling | portion of chorion is removed to test for genetic disease |
