Topic 4 - Muscle Contraction

Question 1

Describe Myosin filaments

Answer 1

• They have globular heads that are hinged, so they can move back and forth
• Each head has a binding site for Actin and one for ATP

Question 2

Describe Actin filaments

Answer 2

• Have binding sites for myosin heads (actin-myosin binding sites)
• Tropomyosin (A type of protein) is found between actin filaments. It helps myofilaments move past each other

Question 3

What is tropomyosin?

Answer 3

A protein found between actin filaments attached to another protein. Together the two proteins help myofilaments move past each other

Question 4

Why can myofilaments not slide past each other in resting muscles?

Answer 4

Because the actin-myosin binding site is blocked by tropomyosin, which means the myosin head cannot bind to the actin-myosin binding site