8 Number the following events of skeletal muscle contraction in the proper order

Question

8 Number the following events of skeletal muscle contraction in the proper order, with number 1 for the first eve and number 6 for the last event. A power stroke occurs as myosin moves into its relaxed position and pulls the thin filament toward the M Calcium ions bind to troponin, which pulls tropomyosin away from actin. ATP breaks the actin-myosin attachment, after which ATP is hydrolyzed and myosin is recocked. The myosin head binds to an actin subunit. The energy from ATP hydrolysis "cocks" the myosin head into an upright position. The terminal cisternae of the sarcoplasmic reticulum release calcium ions into the sarcoplasm. 9 Maximal tension in a skeletal muscle contraction is generated a. when the sarcomeres are at about 100 to 120 percent of their natural length. b. when the muscle fiber is stretched before the contraction. c. when the muscle fiber is shortened before the contraction, and there is a maximal zone of overlap d. when the sarcoplasmic reticulum releases fewer calcium ions

Explanation / Answer

Question 8: 1. the terminal cisternae of the sarcoplasmic reticulum release calcium ions into the sarcoplasm

2. calcium ions bind to troponin, which pulls tropomyosin away from actin

3. The energy from ATP hydrolysis cocks the myosin head into an upright position

4. The myosin head binds to an actin subunit

5. A power stroke occurs as myosin moves into its relaxed position and pulls the thin filament towards the M line

6. ATP breaks the actin myosin attachment, after which ATP is hydrolysed and mysoin is recocked

Question 9: a. when the sarcomeres are at about 100 to 120 percent of their natural length

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