Allele One of the forms of a gene for a given trait.
Base A portion of the DNA molecule. DNA has four bases: adenine(A), thymine (T), cytosine (C), and guanine (G).
Base Pair Two bases that combine and form a “rung” on the double helix DNA molecule. Adenine (A) can only bond with Thymine (T), and Cytosine (C) can only bond with Guanine (G).
Bioengineering Manipulating the genes of plants or animals for a specific purpose.
Bioethicist Someone who studies ethical issues in medicine and genetics.
Carrier A person who has a recessive gene for a genetic disease, but does not develop the disease because he or she also has a dominant partner gene that overrules the recessive gene
Cell fusion When two cells combine to become one. A sperm fertilizing an egg is an example.
Chromosomes Thread-like structures in a cell’s nucleus that contains its DNA
Clone Organisms that have the exact same DNA genomes
Cloning vector A virus or other kind of material that can be used to insert foreign DNA into a cell.
DNA (deoxyribonucleic acid) The basic molecule of heredity that contains all genetic material.
DNA sequencing The process of determining the exact order of the base pairs that make up the DNA in a given organism.
Dominant A form of a gene that can override its partner allele.
Double helix The shape of the DNA molecule, made up of two spirals, with hydrogen bases connecting them.
Gene The basic unit of heredity A gene is a portion of DNA.
Gene therapy A form of medicine in which genes are manipulated in order to correct diseases caused by genetic defects.
Genome The sum of all of the DNA on the chromosomes in a given organism. Every living organism has its own distinctive genome.
Heredity Passing of traits from one generation to the next.
Heterozygous When two alleles for a given gene are different.
Homozygous When two alleles for a given gene are the same.
Human Genome Project A joint scientific effort in which the entire human genome was mapped.
Mitosis nuclear division involving duplication and separation of the chromosomes.
Nuclear transfer A process of cloning in which the DNA from an adult cell is put into an egg cell that has had its nucleus removed. The resulting embryo is then implanted in an animal and brought to term.
Nucleotide A building block of DNA made up of a sugar, phosphate and a base.
Nucleus The central part of a cell that holds its chromosomes (not found in bacteria)
Phenotype The physical manifestation of an organism’s traits.
Prokaryote A one-celled creature lacking a nucleus, such as bacteria.
Recessive An allele whose function is inactive if there is a dominant allele present. It functions only if two recessive alleles are present.
Somatic cells All the cells in a body except for the reproductive cells.
Stem cells Embryonic cells that are still undifferentiated and can develop into any kind of cell in the body.
Transgenic animal An animal that is made up of genes from more than one organism.
Vector In gene therapy, a way of delivering a gene into an existing organism’s cells.