Mechanism of Muscle Contraction

Ca²⁺ released by sarcoplasmic reticulum will bind to ____

• Actin

• Troponin

• Myosin

• Tropomyosin

The part of the sarcomere that labelled D (Red) refers to?

• Actin

• Myosin

• Troponin

• Tropomyosin

What state is the sarcomere in #3?

• Relaxed

• Contracting

• Fully Contracted

• None of the above

What happens to the H zone during a fully muscle contraction?

• It disappears

• It gets closer together

• It gets bigger

• None of these

What is necessary for the myosin to release the actin?

• ATP

• Calcium

• ADP

• Sodium

Explain the sliding filament theory of muscle contraction.

• Actin filaments slide over myosin filaments, shortening the sarcomere and causing muscle contraction.

• Myosin filaments slide over actin filaments, lengthening the sarcomere and causing muscle relaxation.

• Actin and myosin filaments remain stationary, and the sarcomere changes length.

• Myosin filaments dissolve, allowing actin filaments to contract.

Tags

DOK Level 2: Skill/Concept

Describe the role of calcium ions in muscle contraction.

• They bind to troponin, causing a conformational change that allows myosin to bind to actin.

• They provide energy for the contraction process.

• They break down ATP to release energy.

• They transport oxygen to the muscle fibers.

Tags

DOK Level 2: Skill/Concept

What is the role of ATP in the sliding filament theory?

• ATP binds to actin, causing it to slide over myosin.

• ATP provides the energy for myosin heads to detach from actin and reattach for another cycle.

• ATP is not involved in the sliding filament theory.

• ATP binds to calcium ions, facilitating muscle contraction.

Tags

DOK Level 2: Skill/Concept

Predict the effect of a malfunctioning sarcomere on muscle function.

• Muscles would contract more efficiently.

• Muscles would be unable to contract properly, leading to weakness.

• Muscles would become more elastic.

• Muscles would produce more ATP.

Tags

DOK Level 3: Strategic Thinking

Match the following:

• Muscle fibers

• Myofibrils

• Thick fibers

• Myosin

• Thin fibers

• Actin