Heat-shock response, Biology

Assignment Help:

Heat-shock Response

When growing plantlets or tissues of plants are shifted to 42°C and above, the synthesis of normal proteins rapidly declines and instead a set of new proteins appears. Since these proteins are known to be induced by hike in temperature, they are often called heat-shock proteins (hsp). These proteins are known to be self-regulatory in that their synthesis is switched off after 6 to 8 hours at the elevated temperature while synthesis of the normal proteins resumes. The heat-shock proteins span over a wide range of molecular weight (15 to 102 kd). Several hsps are known to be induced also by heavy metals and arsenites.

The hsps are now known to occur in representatives of all the major groups of organisms. Curiously, a pre-treatment at elevated temperature (e.g., 2 hours at 45°C) eliminates the heat-shock response on subsequent exposure to similar conditions. It is believed that heat shock protein2 protect essential enzymes and nucleic acids from denaturation. Induction of synthesis of heat-shock proteins has also been observed under field conditions. In dry fields during summer when the leaf temperature reaches or exceeds the ambient temperature (>40"C), hsp's are synthesised as under experimental conditions.

Heat-shock response involves changes in transcriptional as well as translational control. The pre-existing transcripts for normal proteins remain intact for sometime while protein synthesis ceases. How do hsp's help in heat-shock avoidance? They probably help important cellular proteins to acquire conformations that would be safe and functional under high temperature and the protein will remain in soluble state in the cytoplasm.


Related Discussions:- Heat-shock response

How mineral salts participate in enzymatic activity, Q. How mineral salts p...

Q. How mineral salts participate in enzymatic activity? Many mineral salts are cofactors of enzymes that are the substances without which enzymes do not work.

Describe open circulatory system, Q. What is an open circulatory system? ...

Q. What is an open circulatory system? Open circulatory system is the one in which blood doesn't circulate only inside blood vessels but it also falls in cavities that irrigate

Define the term- adaptation, Define the term- Adaptation The terms sco...

Define the term- Adaptation The terms scotopic and photopic vision are relative to the lighting conditions of an individual place. Light adaptation is a very quick process and

What is coelom - body cavity explain, What is Coelom - Body Cavity explain?...

What is Coelom - Body Cavity explain? Among the bilaterally symmetrical organisms, animals have three different types of body plans with respect to body cavities. The term coel

The human impact on the environment, what are the principle sources of exce...

what are the principle sources of excessive nitrate and phosphate in rivers and lakes?

Define seminal plasma in human male, Seminal plasma in human males is rich ...

Seminal plasma in human males is rich in : 1. fructose and calcium 2. glucose and calcium 3. DNA and testosterone 4. ribose and potassium Fructose and Calcium

Oxidative phosphorylation, Oxidative phosphorylation Oxidative phosphor...

Oxidative phosphorylation Oxidative phosphorylation is a metabolic pathway which uses energy released through the oxidation of nutrients to generate adenosine triphosphate (ATP

What is esophagus called, What is the valve that separates the stomach from...

What is the valve that separates the stomach from the esophagus called? What is its function? The valve that separates the stomach from the esophagus is the cardia. It has the

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