Skeletal Muscle Contraction

What exerts the pulling force in muscle contraction?

• Myosin

• Actin

• Tropomyosin

• Troponin

What is the result of the shortening of muscle fibers?

• Muscle contraction

• Muscle relaxation

• Muscle elongation

• Muscle fatigue

Fill in the blank: A group of myosin molecules forms a _________.

• thick filament

• thin filament

• muscle fiber

• sarcomere

What do actin molecules consist of?

• A) Globular proteins arranged in twisted filaments

• B) Linear proteins arranged in straight filaments

• C) Fibrous proteins arranged in sheets

• D) None of the above.

Fill in the blank: Troponin and tropomyosin are two proteins associated with the surface of the actin molecules; together, these three proteins form the ________.

• thin filaments

• thick filaments

• myosin heads

• sarcomere

What role does Tropomyosin play in the structure of Actin filaments?

• It binds calcium ions

• It blocks the active binding site on Actin molecules

• It forms a double strand helix

• It displaces Troponin

Identify the myosin heads:

Identify troponin:

According to the sliding filament model of muscle contraction, a myosin head attaches to what during muscle contraction?

• Actin filament

• Tropomyosin

• Troponin

• Calcium ions

What is formed when a myosin head attaches to a binding site on the actin filament?

• A cross-bridge is formed

• An actin filament is broken

• A myosin filament is created

• ATP is released