allele: form of gene, one of two or more alternative forms of a gene, occupying the same position on paired chromosomes and controlling the same inherited characteristic.
amino acid: constituent of protein, an organic acid containing one or more amino groups, especially any of a group that make up proteins and are important to living cells. Some can be synthesized by the body nonessential amino acids and others must be obtained through the diet essential amino acids.
autosomal disorder: a genetic condition caused by a defective gene carried on a chromosome other than a sex chromosome.
carrier: transmitter of genetic defect. An individual carrying a gene for a particular genetic trait or disorder without being affected by it, because two copies of the gene, one from each parent, are usually necessary for the disorder to show itself.
chromosome: rod-shaped structure carrying genes, a rod-shaped structure in a cell nucleus carrying the genes that determine sex and the characteristics an organism inherits from its parents. A normal human body cell contains 46 chromosomes arranged in 23 pairs.
codominant: with equal genetic effect, used to describe genes that each have equal effect in making the character they control appear in offspring. The genes for normal hemoglobin, A, and sickle hemoglobin, S, are codominant. If they are both inherited they give rise to the AS and are sickle cell carriers (have the trait).
deoxygenate: to remove dissolved oxygen from a substance.
gene: basic unit of heredity, the basic unit capable of transmitting characteristics from one generation to the next. It consists of a specific sequence of DNA or RNA that occupies a fixed position on a chromosome.
hemoglobin: an iron-containing protein in red blood cells that combines reversibly with oxygen and transports it from the lungs to body tissues.
heterozygous: having genetic variant, used to describe a cell or organism that has two or more different versions ( alleles) of at least one of its genes. The offspring of such an organism may thus differ with regard to the characteristics determined by the gene or genes involved, depending on which version of the gene they inherit.
homozygous: having two identical genes at the corresponding loci of homologous chromosomes.
inherit: receive a characteristic or quality from a parent: to receive a characteristic or quality as a result of its being passed on genetically.
mutation: change in genetic material, a random change in a gene or chromosome resulting in a new trait or characteristic that can be inherited. Mutation can be a source of beneficial genetic variation, or it can be neutral or harmful in effect.
phenotype: the visible characteristics of an organism resulting from the interaction between its genetic makeup and the environment.
pleiotropy: gene property, the phenomenon or instance in which a single gene determines two or more apparently unrelated characteristics of the same organism.
polypeptide: amino-acid chain, a natural or synthetic compound consisting of linked amino acids. Proteins are polypeptides.
protein: complex natural compound, a complex natural substance that has a high molecular weight and a globular or fibrous structure composed of amino acids linked by peptide bonds. Proteins are essential to the structure and function of all living cells and viruses.
recessive: producing effect in certain conditions only, used to describe a gene that produces an effect in an organism only when its matching allele is identical. The effect is masked when the matching allele is nonidentical.
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