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

Division of the exconjugant into daughter paramoecia, Division of the excon...

Division of the exconjugant into daughter paramoecia: Each exconjugant, with a single micronucleus and four macronuclei divides twice and forms four daughter paramoecia. E

Tell us about three kinds of dna, There are 3 types of DNA sequences. Genom...

There are 3 types of DNA sequences. Genomic DNA comes from the genome and haves both genes and extragenic material. cDNA is reverse transcribed from mRNA and corresponds only

Show the regulation of blood pressure, Q. Show the Regulation of blood pres...

Q. Show the Regulation of blood pressure? Nervous System control of BP Maintains primarily an adequate systemic BP, and alters blood distribution in body to meet specific fu

Name term for white blood cells producing immunoglobulins, Which of the bel...

Which of the below is a term for mononuclear, granulocytic white blood cells which produce immunoglobulins? a) Platelets b) Lymphocytes c) Erythrocytes (pron: eh-rith-reh

Life forms, why are life forms significant?

why are life forms significant?

What is an accommodation, What is an accommodation? Accommodation is th...

What is an accommodation? Accommodation is the ability of the eye to focus on an object situated at variable distances from the eye. Like a camera, even the eye requires to cha

What is the kind of digestion occurs in cnidarians, Q. What is the kind of ...

Q. What is the kind of digestion that occurs in cnidarians? These animals have a digestive cavity and they make intracellular and extracellular digestion. The extracellular dig

Closed heart surgery, CLOSED HEART SURGERY :  Operative procedures on ...

CLOSED HEART SURGERY :  Operative procedures on the heart or major intra thoracic vessels done when the heart is beating and supporting effective circulation come under the ca

Patient after cardiac transplant, Patient after cardiac transplant ...

Patient after cardiac transplant The major focus of medical and nursing care after transplantation is to prevent early identification of rejection so that appropriate

Which equipments are required for stress laboratory, The stress lab must ha...

The stress lab must have the following equipment: 1) A mercury Blood Pressure apparatus. 2) A Bed so that the patients ECG can be recorded in the recovery period in supine po

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