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Reg of Expression
Terms from Regulation unit at NW 04-350
| Term | Definition |
|---|---|
| environmental signal | some substance in the environment responsible for triggering a change in gene expression. Could be chemical substance, radiation, temperature, pH, or environmental condition |
| structural gene | gene that is coding for a metabolic enzyme or protein used to build a structure |
| constitutive expression | genes that are always being expressed, and therefore not regulated, are constitutively expressed |
| housekeeping genes | genes coding for absolutely essential proteins that are constantly being expressed because they are always needed. not regulated |
| regulatory product | protein or RNA that influences the expression of other genes by binding to the regulatory element. may influence transcription or translation. trans acting |
| regulatory element | nucleic acid sequence (DNA or RNA) which the regulatory product attaches, influencing the expression of genes physically connected to the element. cis acting |
| positive control | when a genes expression is stimulated by binding of regulatory product to the regulatory element, but expression is turned off when they do not bind |
| negative control | when a genes expression is repressed by binding of a regulatory product to the regulatory element, but expression is turned on by their failure to bind. |
| activator | a regulatory product responsible for positive control |
| repressor | a regulatory product responsible for negative control |
| inducible | when gene expression is stimulated by the presence of an environmental signal |
| repressible | when gene expression is turned down by the presence of an environmental signal. |
| inducer | an environmental signal responsible for inducible expression |
| operon | system of regulation common in prokaryotes. involves multiple genes coding for proteins involved in the same biochemical process sharing a single promoter and regulatory element. when one gene is expressed all are expressed. produces a polycistronic mRNA |
| promoter | site where initiation of transcription occurs due to binding of RNA polymerase |
| operator | common term for a regulatory element adjacent to the promoter. binding site for a regulatory product |
| lac operon | cluster of co regulated genes involved in lactose metabolism |
| Lac Z | gene coding for Beta Galactosidase, the enzyme that breaks lactose into monosaccharides glucose and galactose |
| Lac Y | gene coding for permease, transporter protein used to move lactose into the interior of the cell from the external environment |
| Lac A | gene coding for trans acetylase |
| Lac I | gene coding for the lac repressor, will shut down expression of the operon in the absence of lactose by binding to the operator |
| catabolite activator protein (CAP) | regulatory product involved in positive regulation of lac operon and others as a response to glucose concentration |
| cAMP | cyclic adenosine monophosphate, common metabolic signalling molecule. concentration is inversely related to glucose concentration |
| antisense RNA | a small RNA molecule that is the reverse complement of a normal mRNA. the two may hybridize, preventing translation by blocking the ribosomal binding site in prokaryotes |
| riboswitch | used in the regulation of translation. a molecule that alters the structure of the 5' UTR of mRNA, preventing the ribosome from binding or accessing the start codon |
| chromatin structure | level of organization of a eukaryotic chromosome, euchromatin vs heterochromatin |
| acetylation | addition of an acetyl group, cancels out the positive charge of histone proteins, causing chromatin structure to loosen |
| deacetylation | removal of an acetyl group |
| sex lethal (sxl) | protein produced in female fruit flies that alters the splicing of the tra mRNA, producing a functional protein. males don't express sxl so tra mRNA is spliced in a different way, producing a nonfunctional protein |
| gal4 | activator of gal1 expression by binding to UAS and making contact with the mediator |
| gal80 | repressor protein that blocks gal4 from making contact with the mediator, and therefore stops expression of the gal1 gene |
| gal3 | repressor of the repressor gal80... therefore an activator. prevents gal80 from blocking contact between gal4 and the mediator. responds to galactose concentration as an environmental signal |
| upstream activation sequence (UAS) | name given to the enhancer influencing gal1 expression |
| western hybridization | technique used to measure the amount of protein present by binding a specific protein with an antibody probe |
| northern hybridization | technique used to measure the amount of RNA present by binding a labelled DNA probe to an RNA |
| primary antibody | immunoglobulin that recognizes the 3d shape of a protein (epitope) and is able to bind |
| secondary antibody | immunoglobulin that recognizes the shape of a primary antibody. secondary is produced in large volumes to allow conjugation with other substances (enzyme, fluorescent compound, gold particle) |
| hybridization | general term used to describe any time one molecule binds with another. could be two dna strands or one dna strand and one rna strand or two proteins |
| microarray | technique used to measure the amount of RNA expression for many genes simultaneously. involves hybridizing cDNA with gridded spots of DNA sequence on a substrate |
| reverse transcriptase | enzyme used to convert RNA into its DNA coding sequence, cDNA. done to give a more stable molecule to work with in the lab instead of unstable RNA |
| reporter gene | gene whose protein product is easily detectable (enzymatic reaction, light production etc). often attached to regulatory element and used to make transgenic organisms to identify where expression of a gene would normally occur |
| transgenic organism | organism that has been genetically altered so that it is carrying a foreign piece of DNA |
Created by:
jthorns
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