| A | B |
|---|
| gametes | sperm and ovum |
| chromosome | a DNA molecule |
| genotype | a person's entire genetic inheritance |
| phenotype | the behavioral or physical expression of genetic potential |
| monozygotic | identical twins |
| dizygotic | fraternal twins |
| additive | a pattern in which each gene in question makes an active contribution to the final outcome |
| fragile-X syndrome | a chromosomal abnormality |
| carrier | a person who has a recessive gene in his or her genotype that is not expressed in the phenotype |
| zygote | the first cell of the developing person |
| alleles | alternate versions of a gene |
