Glossary C

Capsid: The protective shell of protein that surrounds the genetic material of a virus.

Capsomere: A protein-based subunit of a viral capsid (the protective protein shell that protects the genetic material of a virus). Capsomeres are designed to attract each other in a certain pattern - when enough are present, they self-assemble to form the capsid.

Carbohydrate: An organic compound composed of carbon, hydrogen, and oxygen, with a 2 to 1 ratio of hydrogen to oxygen. Sugars, starches, and cellulose are all forms of carbohydrate.

Catalyst: A substance, usually present in small amounts, that influences the rate of a chemical reaction without being changed in the process.

Cell: The smallest component of a living organism (with the exception of viruses, which do not have cells). Some organisms, like bacteria and algae, consist of only a single cell, which contains all of their functions and processes. More complex organisms (like humans, for example), consist of large numbers of specialized cells (heart cells, muscle cells, blood cells, etc.) which combine to form the larger organism. A typical cell consists of a

cell membrane or cell wall (sort of like the cell's skin) which contains the cell's structures, a cytoplasm (a jelly-like substance which fills the cell), a nucleus (a central structure within the cell which contains genetic material), and a number of smaller components which are responsible for generating energy, disposing of waste, and producing materials necessary for the operation of the cell.

Cell Membrane: A delicate structure which encloses the cell, separating the contents of the cell from the surrounding environment.

Cell Wall: A semirigid, permeable structure that is composed of cellulose, lignin, or other substances and that envelopes most plant cells.

CD4: Another name for a "helper" T-cell.

CD8: Another name for a "killer" T-cell.

Chylomicrons: Minute fat particles present in lymph which normally are quickly cleared from the blood.

Chronic hepatitis: A long-lasting, progressive destruction of the liver, leading eventually to cirrhosis and liver failure.

Chronic infection: An infection of slow progress and persisting over a

long period of time.

Chronic liver disease: A liver disease of slow process and persisting over a long period of time, resulting in a progressive destruction of the liver.

Circular Deoxyribonucleic Acid: A single or double stranded ring of DNA found in certain bacteriophages and in the human wart virus.

Cirrhosis: Scarring of the liver tissue, usually as the result of hepatitis. Scarring of liver tissue renders the tissue useless in liver function, and can reduce the function of or restrict blood flow to surrounding liver tissue.

Citric acid: A colorless crystalline acid.

Coinfection: Infection with a virus when another infection is already present - hepatitis D, for example, only infects people who are already infected with hepatitis B.

Cytoplasm: The jelly-like protoplasm or substance that fills the interior spaces of a cell.

Cytochrome: A respiratory enzyme capable of undergoing alternate reduction and oxidation.

Cytosine: A pyrimidine base; one of the four basic nucleotides that comprise DNA.