The important terms and definitions you need in order to understand the Human Genome Project include:

Genome: The genome is a term for all the DNA in a living organism.

DNA: Short for deoxyribonucleic acid, DNA is the basic material of which our genes and genome are made. DNA resembles a twisted rope ladder. The side rails are composed of sugar and phosphate molecules, often called the backbone, and the rungs consist of base pairs.

Base pairs: The chemical structures that make up the rungs of DNA, the four bases are adenine, thymine, cytosine and guanine. The bases are constructed so that adenine pairs only with thymine and cytosine pairs only with guanine. Thus, they are referred to as base pairs. When a cell divides, it must first duplicate or replicate its complete set of DNA. When the DNA ladder is split down the middle of each rung, one half of each base pair stays with each sugar phosphate backbone strand. As new DNA is generated, the proper base pairs are made again, so that the two new strands of DNA are exact copies of the parent strand.

Chromosomes: Chromosomes are large molecules of DNA containing, in humans, between 50 million and 250 million base pairs. Human cells other than eggs and sperm contain 23 pairs of chromosomes, for a total of 46. Eggs and sperm contain a single copy of each chromosome, so that when an egg and a sperm cell fuse in fertilization, the resulting fertilized cell contains the necessary 23 pairs. Chromosomes contain multiple different genes.

Genes: Genes are considered the basic units of heredity. Genes consist of specific series of bases, and the order in which the bases appear determines the function of each gene. Genes carry the code for proteins. The human genome is estimated to contain about 30-40,000 genes, but only 2% the genome is genes. The other 98% of DNA contains what are called noncoding regions. The use for the noncoding regions is not entirely known as yet.

Proteins: Proteins are large molecules that perform most of the functions of cells and organs. The building blocks of proteins are amino acids. The groupings of bases along genes tells the body what amino acid comes next in the building of a protein. The body's protein making machinery "reads" the bases in groups of three and inserts whatever amino acid corresponds to that group of three into a growing protein molecule.