Question

myosin, a protein found in muscle cells, is responsible for relaxing and contracting all muscles cells in your body. myosin is able to contract muscle fibers by walking along the muscle fiber. this walking process requires energy and is shown in the diagram below. you can see the myosin in pink and the muscle fiber it is walking along in gold. which of the following statements explains how the myosin is able to use energy to move along muscle fibers?
myosin uses important energy molecules like glucose to energize the muscle cell, by adding a phosphate group to adp to make atp.
myosin breaks down atp to make quick energy in the form of glucose to contract the muscle cells.
myosin breaks the bonds in its amino acid chain to make atp and move along the muscle cells.
myosin breaks bonds in atp to release energy that allows the myosin to move up the muscle cell allowing it to contract.

Explanation:

Myosin is an ATPase enzyme. When ATP binds to myosin, it undergoes hydrolysis. The energy released from the breakdown of ATP (by breaking its bonds) is used by myosin to change its conformation and move along muscle fibers (actin filaments in muscle contraction). This energy - driven movement is crucial for muscle contraction.

• The first option is correct because the energy for myosin movement comes from ATP bond - breaking.
• The second option is wrong as myosin doesn't break bonds in its amino - acid chain to make ATP.
• The third option is incorrect because myosin doesn't break down ATP to make glucose.
• The fourth option is wrong because adding a phosphate group to ADP to make ATP is not how myosin gets energy for movement.

Answer:

Myosin breaks bonds in ATP to release energy that allows the myosin to move up the muscle cell allowing it to contract.