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

Loading and unloading of sieve tubes, Loading and Unloading of Sieve Tubes ...

Loading and Unloading of Sieve Tubes In order to understand the loading of food from manufacturing leaf cells to sieve tubes we must examine the anatomy of a minor vein shown

Natural selection and genetic drift, Tell me which statement belongs to eit...

Tell me which statement belongs to either natural selection, genetic drift, or gene flow Can you tell me if I am correct? -Consistently causes a population to become better adapted

Define the buffer capacity - nutritional biochemistry, Define the Buffer ca...

Define the Buffer capacity - Nutritional Biochemistry? Buffer capacity can be defined as, 'the capacity of a solution to resist changes in pH on the addition of strong acid or

Explain about adhesive tape of many varieties, Explain about Adhesive tape ...

Explain about Adhesive tape of many varieties Adhesive tape of many varieties with backing materials coated with an adhesive to keep the dressing in place. The adhesive bandage

Define rna synthesis , The general mechanism of RNA synthesis by these euk...

The general mechanism of RNA synthesis by these eukaryotic RNA polymerases is the same as for the prokaryotic enzyme that is: ?   The initiation  of RNA synthesis  by RNA polyme

#sponges, expanciate the process of oxygen and carbon dioxide exchange in s...

expanciate the process of oxygen and carbon dioxide exchange in sponges

What is the scientific means about cat and mouse, Toxoplasma cycles between...

Toxoplasma cycles between its rodent and feline hosts, living out different phases of its existence in each. What is the scientific means about the cat and mouse?

What do you mean by the glycolytic or gluconeogenic enzyme, Which of the fo...

Which of the following activators is correctly paired with the glycolytic or gluconeogenic enzyme that is activates? -AMP: Fructose 1,6 Bis -Citrate: Fructose 1,6 Bis -Fru

How is excretion done in fishes, Q. How is excretion done in fishes? Fi...

Q. How is excretion done in fishes? Fishes have a pair of kidneys that filtrate the blood, bony fishes excrete nitrogen as ammonia NH3 (they are ammoniotelic) and cartilaginous

Define precautions for estimation of vitamin c in a solution, Define Precau...

Define Precautions for estimation of vitamin c in a solution? 1. Rinse all glassware with 3% metaphosphoric acid before you begin your practical and subsequently each time you

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