Question

draw a short comic that illustrates the steps of muscle contraction (including stimulus for contraction, excitation-contraction coupling, contraction, cross bridge cycling, and relaxation). Your finished drawing should have a minimum of 7 “panels” - one for each step of muscle contraction listed above, and one each for the establishment and the conclusion of the story you are telling. All chemical and structural participants in this complex interaction should be accounted for.

All components of your comic should be labelled (which will allow the viewer to distinguish between structures). Captions should be provided for each panel that clearly describe what “action” is occurring in the picture.

Answer 1

The muscle contraction unit is mainly formed by Actin and myosin filament which slide over each other on stimulation.

Step 1)Resting phase- The Myosin binding sites on Actin molecules are covered the resting fibres .

Step 2) Contraction- The Tropomyosin covers the myosin binding site which uncovers on excitation by the release of Ca2+ ions .

Step 3) Ca2+ on binding with Troponin makes Tropomyosin to move.

Step 4) Cross - Bridge cycling - Myosin binds with actin and forms cross bridge.

Step 5) Myosin head pivots and Actin moves . The ADP (ADENOSINE PHOSPHATE) and Pi(INORGANIC PHOSPHATE) are released from Myosin head.

Step 6) Relaxation - Now Myosin releases Actin when fresh ATP (ADENOSINE TRIPHOSPHATE) binds.

Step 7) Myosin binds with Actin and ADP binds with Pi hence ATP forms .

Thus cycle repeats untill the stimulation is provided.