| A | B |
|---|
| heredity | passing of physical characteristics from parents to offspring |
| trait | each different form of a characteristic |
| genetics | the scientific study of heredity |
| fertilization | when egg and sperm join |
| purebred | the offspring of many generations that have the same trait |
| gene | factors that control a trait |
| alleles | the different forms of a gene |
| dominant allele | one whose trait always shows up in the organism when the allele is present |
| recessive allele | trait that is hidden whenever the dominant allele is present |
| hybrid | an organism that has two different alleles for a trait |
| probability | a number that describes how likely it is that an event will occur |
| Punnett square | chart that shows all the possible combinations of alleles that can result from a genetic cross |
| genotype | an organisms genetic makeup, or allele combinations |
| phenotype | an organisms physical appearance, or visible traits |
| homozygous | an organism that has two identical alleles fro 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 of chromosomes is reduced by half to form sex cells; sperm and eggs |
| messenger RNA | copies the coded message from the DNA in the nucleus 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 chromosome |
