Glossary of Scientific Terms

I - J

Immunology
Immunology is the science of molecular self-defense of organisms against infections. It deals with the immune system, a complex organ that produces both cells and proteins involved in detecting and destroying foreign molecules and microorganisms (the 'non-self'). It is most elaborate in mammals. The immune cells are white blood cells, originate from the bone marrow and mature in the lymph system. Some of these cells produce antibodies (proteins) that circulate in the blood as a result of a detected infection. These antibodies can be produced for a very long time after the initial infection and are the basis of immunity against further infection by the same microorganism (e.g. flu vaccine). If the microorganism mutates, as if often the case, immunity is no longer given and a new response must be provided by the immune system. In order to avoid costly development of antibodies, the innate immune system provides a broad and less specific protection against a large class of pathogens. Sometimes, the immune system overreacts and destroys cells of the body (the 'self'). The result is an autoimmune disease. Common autoimmune diseases are arthritis, lupus, and type I or juvenile diabetes. There are no known cures for autoimmune disease except for immune system suppressant and pain relievers.

Insulin
A protein hormone that regulates the use of glucose after a carbohydrate rich meal stimulating the degradation of glucose to extract energy and the storage of excess glucose in glycogen or metabolic conversion to fatty acids and cholesterol.

Inorganic
Compounds that do not contain carbon, such as minerals and water. Inorganic is not synonymous with synthetic as is some times erroneously suggested.

Ions
Positively or negatively charged molecules due to an unequal number of protons (+) and electrons (-), mostly one, two, or three. Salts are composed of pairs of ions that readily dissolve in water. Important metal ions in cells are sodium, potassium, calcium, magnesium, zinc and iron. The positively charged metal ions are always found with an equal number of negatively charged counter ions like chloride or phosphate.

Intron
An intron in genetics is a part of a gene, which is excised at the level of the transcript. An intron sequence is a non-coding sequence, meaning it is not translated or used to make a protein. Introns interrupt exons, the protein coding parts of genes. When introns are excised, the exons are spliced together forming a contiguous coding sequence that will be read by the ribosomes and translated into a protein. Introns are found mostly in eukaryotic genes, in some archaea genes and very rarely in bacterial genomes (see also exon).

Joule
The modern unit in physics for energy. Is used in place of calorie. 1 cal equals 4.184 J.