structure of myofibril

What is the basic contractile unit of a myofibril?

• Myofilament

• Sarcomere

• Myofiber

• Z-disc

Which of the following proteins is a component of the thin filament in muscle fibers?

• Myosin

• Actin

• Titin

• Myomesin

The I-band in a sarcomere contains:

• Only thick filaments

• Thick and thin filaments

• Only thin filaments

• No filaments

Which protein blocks the myosin-binding sites on actin in a resting muscle?

• Troponin

• Nebulin

• tropomyosin

• Desmin

During muscle contraction, which band shortens?

• A-band

• I-band

• M-line

• Z-line

Each sarcomere runs from one Z-disc to the next.

• TRUE

• FALSE

Myofibrils are made of repeating units called myofilaments.

• TRUE

• FALSE

8. Tropomyosin is involved in calcium binding during muscle contraction.

• TRUE

• FALSE

The thick filaments of the sarcomere are primarily composed of the protein ___.

Name one protein that helps stabilize or align actin filaments in the sarcomere.