abortion

(1) The intentional ending of a pregnancy, or (2) the natural ejection of a young fetus or embryo from a mother's body.

 

amino acids

Simple chemical units found in all living things. They combine to make up proteins.

 

amniocentesis

A technique for analyzing the genes of a fetus. The test involves sampling the fluid in which the fetus is located.

 

arthritis

A disease that causes painful swelling of one or more joints.

 

augmentation therapy

A form of gene therapy in which cells with healthy genes are introduced into a patient's body to help supply a missing protein.

 

bone marrow

The soft substance that fills the middle of long bones and in which blood cells are made.

 

carrier

A person with a disease-causing recessive gene who does not have the disease but who can pass it on to his or her children. If both parents contribute recessive genes, the child is likely to have the disease.

 

cell

The basic unit that makes up all living things and carries out all of an organism's functions.

 

cell membrane

The flexible outer covering that surrounds an animal or plant cell and controls the passage of chemicals into or out of the cell.

 

chromosomes

The thread-like structures in the nucleus of cells. They carry information about the nature and function of the cell.

 

CVS

Short for chorion villus sampling, a technique for analyzing the genes of a very young fetus. It involves taking a sample of cells from the chorion – the structure that joins the fetus to the mother.

 

cystic fibrosis

An inherited condition in which the sufferer produces large amounts of thick, sticky mucus. The mucus acts as a breeding ground for potentially dangerous bacteria and must be cleared regularly.

 

cytoplasm

The jelly-like material surrounding the nucleus of a cell. It contains the structures that produce the chemicals needed by the cell.

 

diagnosis

The identification of a disease or the cause of an ailment.

 

DNA

Short deoxyribonucleic acid. One of the two nucleic acids found in the nuclei of cells. This molecule decided the composition of proteins.

 

dominant

Describes something that controls or is stronger than something else.

 

fetus

An unborn child from the end of the eighth week of pregnancy to the moment of birth. Before the eighth week the unborn child is known as an embryo.

 

gene

The sequence of DNA that contains the code for a specific protein.

 

gene therapy

The process of altering the genetic code in diseased cells to repair genetic defects.

 

genetic counseling

Advice given to potential parents about the chances that their offspring will inherit certain genetic disorders.

 

genetic disease

A disorder caused by missing or faulty genes.

 

genetic engineering

The science of altering genetic codes in the cells of living things to produce a change in appearance or function.

 

genetic screening

The process of examining the genes of an individual, before or after birth, to predict any genetic disease.

 

hemophilia

An inherited condition in which the sufferer's blood lacks a substance that causes clotting.

 

Huntington's chorea

A genetic disease that causes a progressive breakdown of physical and mental health. Its effects usually start in victims around age 35 or 40.

 

muscular dystrophy

A genetic disease that results in a gradual weakening of a person's muscles.

 

mutation

An accidental change in the DNA making up a gene or chromosome. Mutations can be caused, for example, by exposure to penetrating radiation or certain chemicals. Only if the sperm or egg cells are affected can these changes be passed on to the next generation.

 

nucleus

The place where DNA is stored inside an animal or plant cell. Instructions that control the production of proteins are issued from the nucleus.

 

proteins

A group of substances that are the basis of every cell. Proteins, which are very complex, are made up of hundreds or thousands of combinations of amino acids.

 

recessive

Describes something that is pushed back by, or weaker than, something else.

 

retrovirus

A simple kind of virus that contains only about ten genes.

 

SCID

Short for severe combined immunodeficiency, a genetic disease in which few or no white blood cells are manufactured to protect the body against infection.

 

sex-linked

Having to do with the sex chromosomes, X and Y.

 

sickle-cell anemia

A blood disease caused by a faulty gene that prevents blood cells from forming correctly. The abnormal cells are unable to carry oxygen properly.

 

stem cell

A young cell that has not yet developed into a special-purpose cell.

 

transgenic animal (or plant)

A new type of organism created by mixing together the genes from existing animals or plants.

 

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