Difficulty: Easy
Correct Answer: They localize the pathway’s enzymes together in the same cellular region to facilitate substrate channeling
Explanation:
Introduction / Context:
Cellular metabolism is organized into multistep pathways rather than single giant reactions. A key efficiency gain comes from the spatial organization of enzymes, which can form complexes (metabolons) or colocalize within specific compartments. This architecture reduces diffusion time, protects labile intermediates, and enables coordinated regulation.
Given Data / Assumptions:
Concept / Approach:
When enzymes are localized together, intermediates are passed directly from one active site to the next (substrate channeling). This minimizes loss to competing reactions, decreases effective transit time, and can couple thermodynamically unfavorable steps to favorable ones through proximity and rapid consumption of intermediates.
Step-by-Step Solution:
Verification / Alternative check:
Experimental reconstitution of multienzyme complexes often shows increased flux compared to dispersed enzymes, consistent with channeling and reduced transit times.
Why Other Options Are Wrong:
Common Pitfalls:
Equating pathway efficiency only with thermodynamics; spatial and temporal organization are equally crucial for flux control and robustness.
Final Answer:
They localize the pathway’s enzymes together in the same cellular region to facilitate substrate channeling
Discussion & Comments