Biology Biomolecules MDCAT 2015
PMDC Verified Question 139 of 142
Which molecular structure of enzyme is essential for activity of enzyme?
A
Primary structure
B
Quaternary structure
C
Secondary structure
D
Tertiary structure
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: Tertiary structure
Concept:

An enzyme must have a specific, complex three-dimensional shape (the active site) to bind to its substrate.

Solution:

  • The functional active site of an enzyme is formed when the linear polypeptide chain twists, bends, and folds back upon itself into a complex, 3D globular shape.


  • This overall 3D folding pattern is the Tertiary structure. Without attaining at least the tertiary level, the active site physically does not exist, and the enzyme is utterly inactive.


Why other options are incorrect:

  • Primary/Secondary: These form a straight chain or simple spirals, lacking the 3D pocket required for catalysis.


  • Quaternary: While some enzymes have multiple subunits, many enzymes function perfectly with just a single polypeptide chain in its tertiary state.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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