Which statement best describes the molecular basis of muscle shortening?
A) Individual filamentous proteins contract.
B) Individual filamentous proteins shorten by coiling.
C) Rod-shaped protein polymers shorten by losing subunits from their ends.
D) Protein filaments ratchet along other protein filaments.

Question

Quizplus · Accepted Answer

Muscle shortening is based on the sliding filament theory, which suggests that the thin filaments slide over the thick filaments, leading to muscle contraction. The individual filaments (thin and thick) do not contract or shorten, but rather they remain the same length while sliding and overlapping with each other. Therefore, option D is the best choice since it describes the sliding of protein filaments along each other.

Which Statement Best Describes the Molecular Basis of Muscle Shortening