| A | B |
|---|
| Heredity | the passing of physical characteristics from parents to offspring |
| trait | a characteristic that an organism can pass on to its offspring through genes |
| genetics | the study of heredity |
| fertilization | when egg and sperm join |
| purebred | offspring of many generations that have the same trait |
| gene | factor that controls a trait |
| alleles | different forms of a gene |
| dominant allele | allele whose trait always shows up when the allele is present |
| recessive allele | the allele that is hidden or masked whenever the dominant allele is present |
| hybrid | an organism with two different alleles for a trait |
| probability | a number that describes how likely it is that an event will occur |
| Punnett square | a chart that shows all the possible combinations of alleles that can result from a genetic cross |
| genotype | an organism's genetic makeup or allele combinatioin |
| phenotype | an organism's physical appearance or visible traits |
| homozygous | an organism that has two identical alleles for a trait |
| heterozygous | an organism that has two different alleles for a trait |
| codominance | the alleles are neither dominant or recessive; both alleles are expressed in the offspring |
| meiosis | the process by which the number chromosomes is reduced by half to form sex cells |
| messenger RNA | copies the coded message from the DNA and carries the message to the ribosome |
| transfer RNA | carries amino acids to the ribosome and adds them to the growing protein chain |
| mutation | any change in a gene or a chromosome |
