operon

Inducible Operon - This is a type of operon which is switched on when a chemical, called inducer, is present. The inducer is almost always a substrate. This operon has following componen..

This is a type of operon which is switched on when a chemical, called inducer, is present. The inducer is almost always a substrate. This operon has following componen..

Another type of operon system is the repressible operon which is regulated by a chemical substance called co-repressor. It is almost always the end product of a metabolic reaction. The operon is switched off when the co-repressor, is presen..

In 1961, two French microbiologists, Francois Jacob and Jacques Monod proposed a mechanism, called Operon Hypothesis , for the regulation of gene action in E. coli. It got them the Nobel Prize in 1965. fig. 23.1 - Francois Jacob and Jacques Monod with their Colleague They found that..

These genes produce mRNAs (transcription), which in turn synthesize specific polypeptides on the ribosomes (translation). The polypeptides so formed act as enzymes to catalyse some metabolic reaction in the cell. An operon may have one or more structural genes. The lactose or lac op..

Protein synthesis is a controlled process in which a given protein is synthesised in the cell only when it is necessary. When a particular protein is to be synthesised the specific gene has to express and initiate transcription. The mechanism that stimulates the expression of certain genes ..

This gene is located adjacent to the operator gene. It has two functions. 1.The promoter gene marks the site at which the RNA polymerase enzyme binds. When the operator gene is turned on, the enzyme moves over the operator gene to reach the structural genes and the transcription of mRNA starts. 2...

Inducible operon system consists of structural genes (cistrons), operator gene can either switch on or switch off the structural genes by allowing or not allowing RNA polymerase molecules found attached to promoter gen..

These genes transcribe mRNAs, which are translated by ribosomes and tRNAs into the polypeptides. The latter function as enzymes. The trytophan operon comprises 5 structural genes denoted as E, D, C, B, and ..

An operon is the unit of transcription. When excess protein is present, it is no longer economical for the cell to use up its energy and materials in the synthesis of enzymes that are not immediately needed. Hence, the protein synthesis is stopped. This is clearly advantageous for the cel..