Question

You isolate some muscle fibers to examine what regulates muscle contraction. When you bathe the muscle fibers in a solution containing ATP and Ca^2 , you see muscle contraction (experiment 3). Ca^2 is necessary, as solutions containing ATP alone or nothing do not stimulate contraction and thus the muscle remains in a relaxed (uncontracted) state (experiments 1 and 2). From what you know about the mechanism of muscle contraction, fill in your predictions of whether the muscle will be contracted or relaxed for experiments 4, 5, 6 and 7. Briefly explain each of your answers.

Answer 1

Experiment 4. Relaxed, the drug will stop the calcium so that it does not act on the troponin

Experiment 5. Contraction: In order for the muscle to relax, the actin and tropomyosin union must occur.

Experiment 6. Relaxation: the release of the actin-myosin complex occurs with consumption of ATP, thus it slides and generates contraction, by adding a hydrolyzable analog, this reaction is avoided giving rise to a prolonged actin-myosin binding which leads to relaxation while last effect.

Experiment 7. Ca2 + Contraction is very necessary so that during muscle contraction troponin can be extracted.