Question

Describe and/or illustrate the shortening of a muscle fiber. What provides the energy for this reaction? Where does the force of the contraction come from? What is important about the organization of myosin and actin in the fibers that allow muscles to exert so much force? What regulates the process of muscle contraction?

Answer 1

The molecular events of muscle fiber shortening occur within the fiber's sarcomeres. The constriction of a striated muscle fiber occurs as the sarcomeres, directly orchestrated inside myofibrils, shorten as myosin heads pull on the actin fibers.

This activity requires energy, which is provided by ATP.

In the event that the actin binding sites are revealed, a cross-extension will frame; that is, the myosin head traverses the separation between the actin and myosin particles. Pi is then discharged, permitting myosin to exhaust the put away energy as a conformational change. The myosin head pushes toward the M line, pulling the actin alongside it. As the actin is pulled, the fibers push roughly 10 nm toward the M line. This development is known as the force stroke, as it is the progression at which power is delivered. As the actin is pulled toward the M line, the sarcomere abbreviates and the muscle contracts.

The movement of muscle shortening occurs as myosin heads tie to actin and pull the actin inwards. Myosin binds to actin at a binding site on the globular actin protein.

At the point when the myosin head is positioned, it contains energy and is in a high-energy design. This energy is exhausted as the myosin head travels through the force stroke. Toward the finish of the force stroke, the myosin head is in a low-energy position. After the force stroke, ADP is discharged. Nonetheless, the cross-connect shaped is still set up, and actin and myosin are bound together. ATP would then be able to join to myosin, which permits the cross-connect cycle to begin again and additionally muscle contraction can happen.