Term | Definition |
True breeding | If an organism has a certain characteristic that is always passed on to its offspring, we say that this organism has bred true with regard to that charcteristic |
Mendel's principle #1 | The traits of an organism are determined by its genes. |
Mendel's principle #2 | Each organism has two alleles that make up the genotype for a given trait. |
Mendel's principle #3 | In sexual reproduction, each parent contributes ONLY ONE of its alleles to its offspring. |
Mendel's principle #4 | In each genotype, there is a dominant allele. If it exists in an organism, the phenotype is determined by that allele. |
Allele | One of a pair of genes that occupies the same position on homologous chromosomes |
Genotype | Two-letter set that represents the alleles an organism possesses for a certain trait |
Phenotype | The observable expression of an organism's genes |
Homozygous genotype | A genotype in which both alleles are identical |
Heterozygous genotype | A genotype with two different alleles |
Dominant allele | An allele that will determine the phenotype if just one is present in the genotype |
Recessive allele | An allele that will not determine phenotype unless the genotype is homozygous in that allele |
Pedigree | A diagram that follows a particular phenotype through several generations |
Monohybrid cross | A cross between two individuals, concentrating on only one definable trait |
Dihybrid cross | A cross between two individuals, concentrating on two definable traits |
Autosomes | Chromosomes that do not determine the sex of an individual |
Sex chromosomes | Chromosomes that determine the sex of an individual |
Antigen | A protein that, when injected in the blood, triggers the production of an antibody |
Autosomal inheritance | Inheritance of a genetic trait not on a sex chromosome |
Genetic disease carrier | A person who is heterozygous in a recessive genetic disorder |
Sex-linked inheritance | Inheritance of a genetic trait located on the sex chromosome |
Mutation | A radical chemical change in one or more alleles |
Change in chromosome structure | A situation in which a chromosome loses or gains genes during meiosis |
Change in chromosome number | A situation in which abnormal cellular event in meiosis lead to either none of a particular chromosome in the gamete or more than one chromosome in the gamete |