What is prokaryotic gene expression, Biology

Assignment Help:

What is Prokaryotic Gene Expression ?

Control of prokaryotic gene expression occurs primarily at the level of transcription. Prokaryotic genes are arranged in units consisting of a regulator gene and associated units called operons. An operon consists of a promotor site, an operator site, and structural genes. The regulator gene, adjacent to the promotor and operator sites, produces repressors, protein molecules that bind to the operator site, preventing the attachment of RNA polymerase and the start of transcription of structural genes.

The concentration of certain enzymes, called inducible enzymes, is very much dependent upon the concentration of substrate in the cell. For example, in E. coli, the concentration of beta-galactosidase enzyme is very low in a lactose-free environment, but a large increase of the enzyme proportional to the lactose added to the growth medium is produced by a gene segment called the lac operon.

In high concentrations of lactose, inducer sugar molecules bind to the lac repressors and detach them from the operator, allowing RNA polymerase to bind and protein synthesis to occur. Two other proteins are produced along with beta-galactosidase - a permease and a transacetylase. The beta-galactosidase cleaves lactose into glucose and galactose; the permease facilitates transport of lactose across the bacterial cell membrane. The function of the transacetylase is not clear. When the lactose level decreases, repressors bind to the operator site and the operon becomes inactive.

1741_binding of inducer inactivates the repressor.png


Related Discussions:- What is prokaryotic gene expression

Kidney function test, Kidney impairment is one of the long term complicatio...

Kidney impairment is one of the long term complications of diabetes mellitus. Measurement and monitoring of kidney function parameters such as urea and creatinine, in addition to u

Explain the parts of the microscope, Explain the Parts of the Microscope? ...

Explain the Parts of the Microscope? Microscope, as you may have noticed in Figure or for that matter even seen in a laboratory, is a metal body composed of a base and an arm t

Animals vs plants, Animals vs Plants Organisms are of two main types an...

Animals vs Plants Organisms are of two main types animals and plants, although all the above mentioned Unifying concepts of Biology apply equally to both animals and plants, ye

Explain risk factors and their role in cad, Explain risk factors and their ...

Explain risk factors and their role in cad ? The concept of risk factors constitutes a major advance for developing strategies to prevent CVD. The Framingham Heat Study played

How many cellular nuclei does the pollen tube have, How many cellular nucle...

How many cellular nuclei does the pollen tube of angiosperms have? What is the ploidy of each of these nuclei? The pollen tube that is the mature male gametophyte of angiosperm

Define partition chromatography - basic separation technique, Define Partit...

Define Partition chromatography - basic separation technique? It is a technique in which separation is achieved as a consequence of the relative solubility of a substance in th

General protocol for media preparation, General Protocol for Media Preparat...

General Protocol for Media Preparation A general protocol for media preparation is as follows: 1. Prepare stock solutions one day before the medium is to be made. 2. Wei

Define precipitation or solubility of proteins, Define Precipitation or Sol...

Define Precipitation or Solubility of Proteins? Most of the functional properties are dependent on the degree to which the proteins are soluble. The solubility behaviour provid

What are the physical propertie of sol, What are the physical propertie of ...

What are the physical propertie of sol Sols resemble liquids in their main physical properties - that is, they flow and they do not show rigidity of form. However, when a sol a

Name the primary and secondary minerals found in soils, Name the Primary an...

Name the Primary and secondary minerals found in soils Minerals such as silicate clays and iron oxide, which are formed by breakdown and weathering of less resistant materials,

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd