Question

The following is a list of the events that occur during a muscle contraction. What is the correct sequence of these events? 1. Myosin cross-bridges bind to the actin. 2. The free myosin head splits ATP. 3. Calcium ion is released from the sarcoplasmic reticulum. 4. The myosin head pivots toward the center of the sarcomere. 5. Calcium ion binds to troponin. 6. The myosin head binds an ATP molecule and detaches from the actin.

Answer 1

Answer:

3, 5, 1, 4, 6, 2.

Explanation:

Muscle contraction refers to the actin sliding over myosin in muscle cells, allowing the body to move.

For muscle contraction to occur, three elements are required:

• Nervous system stimulation;

• Contractile proteins, actin and myosin;

• Contraction energy provided by the ATP.

The whole process of muscle contraction happens as follows:

1. Calcium ion is released from the sarcoplasmic reticulum.
2. Calcium ion binds to troponin.
3. Myosin cross-bridges bind to the actin.
4. The myosin head pivots toward the center of the sarcomere.
5. The myosin head binds an ATP molecule and detaches from the actin.
6. The free myosin head splits ATP.