The terms and descriptions provided in this glossary have been completed with the help of several sources:

• National Human Genome Research Institute - Talking Glossary,
• Human Genome Project Information,
• PhRMA Genomics, and the
• Word Central's Student Dictionary (Merriam Webster).

Sources are listed with the definitions.

CD

Cancer

Disease(s) in which abnormal cells divide and grow unchecked. Cancer can spread from its original site to other parts of the body and can also be fatal if not treated adequately. [Talking Glossary]

Carrier

A person who has one copy of the gene mutation for a recessive disorder is called a 'carrier'. Carriers are not affected by the disorder however they can pass on the mutated gene to their children. Children who inherit two such genes may be affected by the disorder.
Source : Human Genome Project Information

Cell

The basic unit of any living organism, a cell is a small, watery, compartment filled with chemicals and a complete copy of the organism's genome. [Talking Glossary]

Chlorophyll

The green coloring matter of plants that is found in chloroplasts and is necessary to make plant food from carbon dioxide and water by photosynthesis.
Source : Word Central's Student Dictionary

Chloroplasts

An area in a plant cell that contains chlorophyll and is the location of photosynthesis and starch formation.

Chorionic villus sampling

Chorionic villus sampling is a prenatal test that can be done earlier than amniocentesis. It is performed on pregnant women who are at risk for carrying a foetus with a genetic or chromosomal defect.

Chromosome

One of the threadlike "packages" of genes and other DNA in the nucleus of a cell. Different kinds of organisms have different numbers of chromosomes. Humans have 23 pairs of chromosomes - so 46 in all - 44 autosomes and two sex chromosomes. Each parent contributes one chromosome to each pair, so children get half of their chromosomes from their mothers and half from their fathers. [Talking Glossary]

Clone

An exact copy of biological material such as a DNA segment (e.g., a gene or other region), a whole cell, or a complete organism.
Source : Human Genome Project Information

Cloning

Cloning creates a genetically identical copy of an animal or plant. Cloning is the process of making copies of a specific piece of DNA, usually a gene. When geneticists speak of cloning, they do not mean the process of making genetically identical copies of an entire organism. [Talking Glossary]

Codon

Three bases in a DNA or RNA sequence, which specify a single amino acid. [Talking Glossary]

Conception

In reproduction, conception is the point at which a sperm fertilizes an egg.

Cystic fibrosis

This is a hereditary disease whose symptoms usually appear shortly after birth. They include faulty digestion, breathing difficulties and respiratory infections due to mucus accumulation, and excessive loss of salt in sweat. In the past, cystic fibrosis was almost always fatal in childhood, but treatment is now so improved that patients commonly live in to their twenties and beyond. [Talking Glossary]

Cytoplasm

The viscous semi-liquid inside the membrane of a cell.

Cytosine

One of the four bases in DNA that make up the letters A, T, C, G. Cytosine is the "C". The others are adenine, thymine, and guanine. Cytosine always pairs with guanine. [Talking Glossary]

Deoxyribonucleic acid (DNA)

DNA is the chemical inside the nucleus of a cell that carries the genetic instructions for making living organisms. A long molecule, and usually packaged into chromosomes, DNA encodes genetic information in the form of a double helix held together by bonds between base pairs. [Talking Glossary]

Disorders

Problems in how the body functions. Health problems caused by mutations in the genes are referred to as genetic disorders.
Source : Human Genome Project Information

Diversity

Diversity describes the the different types of organisms that exist within in a community or ecological system.

DNA

Short for deoxyribonucleic acid.

DNA fingerprinting

In genetics, the identification of multiple specific alleles on a person's DNA to produce a unique identifier for that person.
Source : Human Genome Project Information

DNA polymerase

The enzyme in DNA replication that links the complementary nucleotide bases together to make the newly synthesized strand.

DNA replication

The process by which the DNA double helix unwinds and makes an exact copy of itself. [Talking Glossary]

DNA sequencing

Determining the exact order of the base pairs in a segment of DNA. [Talking Glossary]

Dominant gene

A gene that almost always results in a specific physical characteristic, for example, a disease, even though the patient's genome possesses only one copy. With a dominant gene, the chance of passing on the gene (and therefore the disease) to children is 50-50 in each pregnancy. [Talking Glossary]

Double helix

The structural arrangement of DNA, which looks something like an immensely long ladder twisted into a helix, or coil. The sides of the "ladder" are formed by a backbone of sugar and phosphate molecules, and the "rungs" consist of nucleotide bases joined weakly in the middle by hydrogen bonds. [Talking Glossary]