Category: R

The inhibition of transcription (or translation) by the binding of a repressor protein to a specific site on the DNA (or RNA) molecule. The repressor molecule is the product of a repressor gene.  

An enzyme whose synthesis (rate of production) is inhibited (repressed) when the product that it (or it in a multienzyme sequence) synthesizes is present in high concentrations. It is a way of shutting down the synthesis of an enzyme whose product is not required because so much of it is readily available to the cell.…

The point at which strands of parental duplex DNA are separated in a Y shape. This region represents a growing point in DNA replication.  

Reproduction of the original virus. This process can be viewed as occurring in stages, in which the first stage consists of the adsorption of the virus to the host cell, followed by penetration of the virus (or its nucleic acid) into the cell, the taking over of the cell’s biomachinery and harnessing of it to…

A virus containing double-stranded RNA. It is isolated from the respiratory and intestinal tracts of humans and other mammals. The prefix “reo-” is an acronym for respiratory enteric orphan. A virus which affects both the intestine and the respiratory system, but does not cause serious illness. One of a group of small RNA containing viruses…

Those chemicals that act to block the hypertensive (i.e., high blood pressure-inducing) effect of the enzyme, renin.  

A proteolytic enzyme that is secreted by the juxtaglomerular cells of the kidney. Its release is stimulated by decreased arterial pressure and renal blood flow resulting from decreased extracellular fluid volume. It catalyzes the formation of angiotensin I from hypertensinogen. Angiotensin I is then converted to angiotensin II by another enzyme located in the endothelial…

The return to the natural structure of a protein or nucleic acid from a denatured (more random coil) state. For example, a protein may be denatured [lose its native (natural) structure] by exposure to surfactants such as SDS or to changes in the pH of the medium, etc. If the surfactant is slowly removed or…

The cleanup or containment (if chemicals are moving) of a hazardous waste disposal site to the satisfaction of the applicable regulatory agency [e.g., the Environmental Protection Agency (EPA)]. Such cleanup can sometimes be accomplished via use of microorganisms that have been adapted (naturally or via genetic engineering) to consume those chemical wastes that are present…

A DNA sequence involved in regulating the expression of a gene, e.g., a promoter or operator region (in the DNA molecule).