| A | B |
|---|
| trait | a characteristic that an organism can pass to its offspring through its genes |
| heredity | the passing of traits from parent to offspring |
| genetics | the scientific study of heredity |
| purebred | an organism that always produces offspring with the same form of a trait as the parent |
| gene | the factors that control traits |
| allele | the different forms of a gene |
| dominant allele | an allele whose trait always shows up |
| recessive allele | an allele that is masked when a dominant allele is present |
| hybrid | an organism that has two different alleles for a trait |
| Punnett Square | a chart that shows all the possible combinations of alleles |
| probability | the likelihood that a particular event will occur |
| phenotype | an organism's physical appearance |
| genotype | an organism's genetic makeup or allele combination |
| homozygous | an organism that has two identical alleles for a trait |
| heterozygous | an organism that has two different alleles for a trait |
| codominance | when the alleles are neither dominant nor recessive |
| sperm | the male sex cells |
| egg | female sex cells |
| meiosis | the process by which the number of chromosomes is reduced by half to form sex cells |
| messenger RNA | copies the coded message from the DNA in the nucleus and carries the message to the cytoplasm |
| transfer RNA | carries amino acids and adds them to the growing protein |
| mutation | any change in a gene or chromosome |
