Which energy is used in cellular metabolism?

AIIMS Delhi NO - 2017

Applied Nutrition & Dietetics

Easy

Appeared in: AIIMS Delhi NO - 2017

Explanation

ATP (Adenosine Triphosphate) is the principal molecule for storing and transferring energy within cells.
It is a nucleotide composed of an adenine base, a ribose sugar, and three phosphate groups.
Energy is released for cellular work when the terminal high-energy phosphate bond is broken, converting ATP into ADP (Adenosine Diphosphate) and inorganic phosphate.
This released energy powers almost all cellular functions, including biosynthesis, muscle contraction, and active transport across membranes.

Option B: ADP (Adenosine Diphosphate) is the result of ATP releasing its energy. It is in a lower-energy state and must be 'recharged' back into ATP to be used as an energy source.
Option C: ASP stands for Aspartic acid, which is an amino acid. Amino acids are the building blocks of proteins and are not used as the primary, immediate energy currency of the cell.
Option D: AMP (Adenosine Monophosphate) has only one phosphate group and contains even less energy than ADP. It is not a direct source of energy for most reactions.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Cellular energy currency as background academic context rather than a clinical decision trigger.
Understanding ATP's role is crucial for comprehending diseases involving energy deficits, such as mitochondrial myopathies or ischemia, where impaired ATP production leads to cell dysfunction and death.
Nurses monitor patients for clinical signs of cellular hypoxia (e.g., altered mental status, cyanosis, elevated lactate), which are direct consequences of failed aerobic ATP production.
What if? If a patient suffers from cyanide poisoning, the poison blocks the electron transport chain, halting the primary mechanism of ATP synthesis (oxidative phosphorylation). This causes a catastrophic and rapid drop in cellular energy, leading to widespread cell death and a life-threatening emergency.

How to Approach the Question

First, identify the keywords in the question: 'energy' and 'cellular metabolism'. This points to the core process of how cells power their functions.
Recall the fundamental molecules of bioenergetics. The question is asking for the main 'fuel' molecule.
Recognize that ATP (Adenosine Triphosphate) is universally known as the 'energy currency' of the cell.
Differentiate ATP from its related but lower-energy forms, ADP (diphosphate) and AMP (monophosphate).
Eliminate unrelated options like ASP (Aspartic acid), which is an amino acid for building proteins, not for immediate energy transfer.
Select ATP as it is the molecule that directly provides energy for most cellular reactions by breaking its high-energy phosphate bond.

Concept Tested & Keywords

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E6 Harper's Illustrated Biochemistry2023 (pp 26-793 of 813) p. 96-98

E6 Textbook of Biochemistry for medical StudentsDM Vasudevan Part 1 (pp 26-370 of 370) p. 128-130

E6 Physiology Guyton 4SAE Part 1 p. 49-51