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| allele | one of the alternative forms of a gene that governs a characteristic, such as hair color |
| genotype | the entire genetic makeup of an organism; also the combination of genes for one or more specific traits |
| phenotype | an organism's appearance or other detectable characteristic that results from the organism's genotype and the environment |
| heredity | the passing of genetic traits from parent to offspring |
| genetics | the science of heredity and of the mechanisms by which traits are passed from parents to offspring |
| probability | the likelihood that a possible future event will occur in any given instance of the event; the mathematical ratio of the number of times one outcome of any event is likely to occur to the number of possible outcomes of the event |
| genes | a segment of DNA that is located in a chromosome and that codes for a specific hereditary trait |
| dominant trait | the trait observed when at least one dominant allele for a characteristic is inherited |
| recessive trait | a trait that is apparent only when two recessive alleles for the same characteristic are inherited |
| sex cells | a gamete or haploid reproductive cell (23 chromosomes- no pairs) that unites with another haploid reproductive cell to form a zygote (46 chromosomes- 23 pairs) |
| homologous chromosomes | one of the pair of chromosomes that determine the sex of an individual |
| meiosis | a process in cell division during which the number of chromosomes decreases to half the original number by two divisions of the nucleus, which results in the production of sex cells (gametes or spores) |
| sex chromosomes | one of the pair of chromosomes that determine the sex of an individual |
| mitosis | in eukaryotic cells, a process of cell division that forms two new nuclei, each of which has the same number of chromosomes |
| heterozygous | when forms of the gene (alleles) occur in different forms |
| homozygous | both alleles (forms of the gene) are the same |
| co-dominance / incomplete dominance | When the alleles of the trait blend. Neither allele dominates. |
| punnett square | a tool used to predict probability of certain traits in offspring. It shows the phenotype and genotype and the possible combination of alleles that can result when genes are crossed. |
| trait | Ways of looking, thinking, or being |
| Gregor Mendel | An Austrian monk who made careful use of scientific methods, which resulted in the first recorded study of how traits pass from one generation to the next. |
| haploid | A set of chromosomes containing only one member of each chromosome pair (23 chromosomes or N) |
| diploid | This cell has one chrosome form each parental set. Two sets of human chromosomes contain 46 total (2N) |
| asexual reproduction | A new organism is produced form one organism. The offspring will have identical genetic information. |
| sexual reproduction | Requires two cells- one form each parent. The sex cells join to form an entirely new organism. |
