After a very few hours of sleep you have arrived at the venue to take your MCAT

Question

After a very few hours of sleep you have arrived at the venue to take your MCAT exam. Your mind is racing and you fear the essay portion of the exam. (For those of you who are not familiar, you are given any topic and asked to write a few paragraphs about it). Large amounts of epinephrine is released into your bloodstream.

During the intracellular transmission of the signal, a second messenger is formed. Name the second messenger.

What is the final cellular response in this cascade?

If the cAMP phosphodiesterase activity is high (due to another intracellular pathway) during the same time, what will be the final cellular response?

If there is a mutation in the phosphoprotein phosphatase involved in this pathway, how will this change the final cellular response?

Explanation / Answer

Adrenalin is usually released in large amounts in blood. Adrenalin is get released from adrenal gland. when we face dtrong emotions like fear, anger then adrenalin is released into blood. This results in increased blood pressure , heart rate ot metabolism of sugar.

In a intracellular signalling pathway of epinephrine , a second messenger cyclic AMP is formed.

The final cellular response of this pathway is generation of protein kinase A and several other effector molecule.

Phosphodiesterase will break down the phosphodiester bond of cAMP and 5'-AMP. As a result cAMP can not be functional and protein kinase A will not be generaed.

The second messenger cAMP will control the protein kinase A which in turn will control the phophorylation stages of gycogen phosphorylase and glycogen synthase. These steps helps to break down glucose. Now, on the other hand phosphoprotein phosphatase-1 is responsible for dephosphorylation of glycogen phosphorylase and glycogen synthase . Thus a mutaiton in phosphoprotein phosphatase will inhibit the dephophorylation state. As a result, gycogen phosphorylase and glycogen synthase will be phophorylated and glucose will glycogenolysis will continue.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.