HP CHO -9 October 2022
Biochemistry & Nutrition
Easy
cAMP is synthesized with the help of enzyme:
Appeared in: HP CHO -9 October 2022
Explanation
- Adenylyl cyclase is the specific enzyme responsible for the synthesis of cyclic adenosine monophosphate (cAMP).
- It catalyzes the chemical reaction that converts adenosine triphosphate (ATP) into cAMP.
- This enzyme is a key component of the signal transduction pathway and is typically activated by a G-protein after a hormone binds to a cell surface receptor.
Why Other Options Were Wrong
- Option A: This enzyme performs the opposite function; it degrades or breaks down cAMP into adenosine monophosphate (AMP), which terminates the cellular signal.
- Option B: Adenosine monophosphate (AMP) is a molecule, not an enzyme. It is the inactive product that results from the breakdown of cAMP by phosphodiesterase.
- Option D: G-proteins are regulatory signal transducers. They are activated by hormone receptors and in turn activate adenylyl cyclase, but they do not directly synthesize cAMP.
Related Visual
Clinical Relevance
- Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Second Messenger System (cAMP pathway) as background academic context rather than a clinical decision trigger.
- Understanding the cAMP pathway is vital in pharmacology, as many drugs target its components. For instance, caffeine and theophylline are phosphodiesterase inhibitors that increase intracellular cAMP levels, prolonging its effects.
- Pathologically, certain toxins hijack this system. Cholera toxin causes irreversible activation of the G-protein that stimulates adenylyl cyclase, leading to massive cAMP production, ion channel disruption in the intestine, and severe, life-threatening watery diarrhea.
- What if? If a patient is taking a phosphodiesterase inhibitor (e.g., sildenafil), the effects of signaling pathways that increase cGMP (a similar cyclic nucleotide) are enhanced, leading to vasodilation. This is the mechanism used to treat erectile dysfunction and pulmonary hypertension.
How to Approach the Question
- First, identify the keywords in the question: 'cAMP', 'synthesized', and 'enzyme'. This directs you to find the specific enzyme that creates cAMP.
- Recall the main components of the cAMP second messenger pathway.
- Systematically evaluate the role of each option: Is it a synthesizer, a degrader, a regulator, or a product?
- Adenylyl cyclase is the synthesizer (creates cAMP from ATP).
- Phosphodiesterase is the degrader (breaks down cAMP to AMP).
- G-protein is the regulator (activates adenylyl cyclase).
Concept Tested & Keywords
- Concept Tested: Second Messenger System (cAMP pathway)
- Stem keywords: cAMP, synthesized, enzyme
- Lead-in keywords: BEST, MOST RELEVANT CLUE
- Negative lead-in flag: false
Question ID
QnmREfffExSLm3XQbTJU3w
Reference Book
E6 Textbook of Biochemistry for medical StudentsDM Vasudevan Part 2 — Subpart B (pp 240-463 of 478) p. 137-139
E6 Robert Boland, Marcia L. Verduin - Kaplan and Sadock's Comprehensive Text of Psychiatry-Wolters Kluwer Health (2024) (pp 1-16525 of 16525) p. 603-605
E6 Harper's Illustrated Biochemistry2023 (pp 26-793 of 813) p. 497-499
Practise the full HP CHO -9 October 2022
Attempt every question from this paper in a timed mock, then review the full solution for each one.
More Clinical Enzymology Questions
- Which one of the following serum enzymes is used in clinical diagnosis of acute pancreatitis?
- Proteins that act as catalysts?
- The agent responsible for catalyzing chemical and physical changes within the cells is?
- An increase in the creatinine kinase MB iso-enzyme (CKMB) can be caused by?
- Telomerase is an enzyme which is?
- The enzyme which catalyzes geometric or structural changes within a molecule is?
- The mineral which functions as a prosthetic group in enzymes is?
- Deficiency of which enzyme results in increased 2,3-BPG levels and low glucose values in vitro?
- The proteins that catalyze biochemical reactions are called:
- Suicidal enzyme complexes often contain:
More HP CHO -9 October 2022 Questions
- Early diagnosis and treatment is an example of:
- Reversibility is a characteristic feature of:
- Which of the following is the best conflict management style?
- Which of the following is NOT an external cause of frustration?
- Individual's life goal is:
- A client expresses the belief that armed forces are out to kill him. This is an example of:
- A false belief unexplained by reality, shared by several people is:
- Preoccupation with body diseases is seen in:
- All are Bleuler's 4 A's of schizophrenia except:
- All are affective disorders EXCEPT: