Structure of Myofilaments Quiz

What are the two myofilaments that make up a sarcomere?

• Actin and myosin

• Actin and troponin

• Tropomyosin and troponin

• Calcium ions and myosin

What is the function of tropomyosin?

• Stiffens and stabilizes actin

• Binds to calcium ions

• Binds to myosin

• Blocks myosin-binding sites

What is the role of troponin?

• Stiffens and stabilizes actin

• Binds to calcium ions

• Blocks myosin-binding sites

• Binds to myosin

What happens when a calcium ion binds to troponin?

• It stiffens and stabilizes actin

• It binds to myosin

• It pulls tropomyosin off of the myosin-binding sites of actin

• It blocks myosin-binding sites

During muscle contraction, which molecule provides the energy for myosin to move along actin filaments?

• ATP

• ADP

• Calcium ions

• Troponin

What is the result of the cross-bridge cycle in muscle contraction?

• Shortening of the sarcomere

• Lengthening of the sarcomere

• Breaking down of actin filaments

• Detachment of myosin heads

Which ion is responsible for the initiation of the muscle contraction process?

• Sodium ions

• Potassium ions

• Calcium ions

• Magnesium ions