chromosomes:

threadlike bodies that carry the genes. They can be seen in the nucleus of a cell just before it divides in two.

clone:

a collection of genetically identical copies of a gene, cell, or organism.

codon:

a triplet of nucleotides that is part of the genetic code and specifies the particular amino acid to be added to a growing chain to make a protein.

cyclosporine:

a drug produced by a soil fungus; it is used to prevent organ rejection by inactivating the body's T-cells.

DNA:

deoxyribonucleic acid. The genetic material of organisms (except retroviruses), made of two complementary chains of nucleotides wound in a helix.

gene:

the physical unit of inheritance, made up of a particular sequence of nucleotides on a particular site on a particular chromosome.

gene expression:

the conversion of the gene's nucleotide sequence into an actual process or structure in the cell. Some genes are expressed only at certain times during an organism's life and not at others.

genetic code:

the sequence of nucleotides in a gene, coded in triplets (codons). The genetic code determines the sequence of amino acids in protein synthesis.

genome:

all the genes in a complete set of chromosomes.

hirudin:

a potent clotting inhibitor produced by leeches. The gene for this protein has now been genetically engineered into canola plants.

Human Genome Project:

an international research effort begun in the 1980s to map and sequence all 100,000 or so genes found in human DNA.

hybridoma:

a fast-growing culture of cloned cells made by fusing a cancer cell to some other cell such as an antibody-producing cell.