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| Term | Meaning | Link |
| beta-galactosidase | This is an enzyme that stimulates the breakdown of complex sugars in to smaller simpler units which can be used to release energy. | 1. Wikipedia |
| CAS | Chemical Abstracts Service (CAS) numbers are unique to each chemical. The American Chemical Society runs this service and they, assign an identifier to every chemical described in relevant literature. Note that CAS numbers are also referred to as CAS RNs or CAS #s. |
1. Chemical Abstracts Service 2. American Chemical Society |
| Enzyme | This the name applied to proteins which can stimulate (or catalyse) chemical reactions. They are essential to biological organisms as they drive and regulate most of the chemical processes that occur in cells. Normally they operate only in specific temperate and PH ranges. | 1. Wikipedia |
| Expression | This is the process in which a cells DNA is read and proteins are created. | 1. Wikipedia |
| Lac (operon) | This is the shorthand for a particular area of DNA in bacteria such as E Coli. The Lac operon is found on the circular DNA of bacteria and is normally switched off. When this gene is switched on (this happens naturally when lactose is in the environment) it produces proteins called permease (that transport lactose from the environment into the bacteria) and beta-galactosidase (which cuts lactose into glucose and galactose). The cell then eats or metabolises the resulting sugars. | 1. Wikipedia |
| Lactose | Lactose is a type of sugar commonly found in milk. | 1. Wikipedia |
| Gene transfer experiments |
In these experiments scientists cut up DNA (genetic material) and select
a specific gene to introduce into a carrier organism - usually a simple
bacteria. This has been done to get bacteria to produce human
insulin for treating diabetes - in this case a human gene was obtained
and inserted into the DNA of bacteria. However in most of these techniques only one in several million bacteria cells will pick up the new gene - this where markers and selective agent come in - they allow scientists to sort those bacteria which have a particular gene of interest from those that do not (see below for further information). |
1. Wikipedia |
| Markers (genetic) | Genetic markers are simply specific areas of DNA which can can pinpointed some how. They can be a tiny area of a gene or DNA strand or whole genes. One type of genetic marker is a 'selectable marker', this gene(s) will keep a cell alive when it is exposed to something that would normally kill it. |
1. Wikipedia 2. Wikipedia |
| Operon | An operon is a section of DNA that contains one or more genes as well as areas of DNA that control the activity of these genes - operators and promoters. | 1. Wikipedia |
| Phenotype | This word is used to describe physical characteristic, or traits, such as eye or flower colour. Some phenotypes are indicative of particular genes are are used as markers for these genes or genotpyes. | 1. Wikipedia |
| Repressor | These proteins are part of the molecular mechanism that controls the expression of genes. These particular proteins bind to an area of DNA called the operator and prevent a gene from being active. | 1. Wikipedia |
| X-gal | X-gal is used by scientists as a phenotypic marker. Bacteria that contain a functioning lac operon produce the enzyme beta-galactosidase which slices X-gal into a chemical which is blue, the blue colonies are visible to the naked eye. They can then be sorted from colonies that do not contain an active gene and are white. The experiment will start with bacteria that do not have a functioning lac operon, small pieces of DNA called plasmids will be mixed up with the cells. The plasmids will contain the DNA the scientist wants to introduce (eg genes to produce insulin to make treatments for diabetics) and the marker DNA - in this case a functioning lac operon. If the cell takes up the plasmid it will produce the insulin protein - but how can the scientist see this and sort the cells producing insulin from the ones that do not? Because the marker gene (lac operon) was also on the plasmid and we can see the blue colour produced when x-gal is added. | 1. Wikipedia |