| A | B |
|---|
| Heredity | The passing of traits from parents to offspring. |
| Trait | A characteristic that an organism can pass on to its offspring through its genes. |
| Genetics | The scientific study of heredity. |
| Fertilization | The process in which an egg cell and a sperm cell join to form a new organism. |
| Purebred | The offspring of many generations that have the same traits. |
| Gene | The set of information that controls a trait; a segment of DNA on a chromosome that codes for a specific trait. |
| Alleles | The different forms of a gene. |
| Dominant allele | An allele whose trait always shows up in the organism when the allele is present. |
| Recessive allele | An allele that is masked when a dominant allele is present. |
| Hybrid | An organism that has two different alleles for a trait; an organism that is heterozygous for a particular 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. |
| Phenotype | An organism's physical appearance, or visible traits. |
| Genotype | An organism's genetic makeup, or allele combinations. |
| Homozygous | Having two identical alleles for a trait. |
| Heterozygous | Having two different alleles for a trait. |
| Codominance | A condition in which neither of two alleles of a gene is dominant or recessive. |
| Meiosis | The process that occurs in the formation of sex cells by which the number of chromosomes is reduced by half. |
| Messenger RNA | RNA that copies the coded message from DNA in the nucleus and carries the message into the cytoplasm. |
| Transfer RNA | RNA in the cytoplasm that carries an amino acid to the ribosome and adds it to the growing protein chain. |
