Actin Myofilament Structure Quiz

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What is the function of the Z disks in a myofibril?

Allow myosin heads to bend during muscle contraction

Release energy through ATP breakdown

Hold the myosin filaments in place (correct)

Form cross-bridges with action molecules

What is the main role of the myosin molecule heads in muscle contraction?

Extend from Z disks to ends of myosin filaments

Bind to active sites of action molecules forming cross-bridges (correct)

Surround each myosin filament with six actin filaments

Breakdown ATP using ATPase enzyme

What is the function of the A bands in a sarcomere?

Extend the length of the myosin filament (correct)

Bind to ATPase enzyme for energy release

Surround each myosin filament with six actin filaments

Hold actin and myosin filaments in place

Which component of the myosin molecule releases energy through ATP breakdown?

Myosin heads Signup and view all the answers

What is the purpose of the I bands in a sarcomere?

Extend from Z disks to ends of myosin filaments Signup and view all the answers

How do Z disks contribute to muscle contraction?

Hold the actin filaments in place Signup and view all the answers

What is the term used to describe muscles that work together in a group to cause a movement?

Synergists Signup and view all the answers

In the context of muscle movements, what is the role of fixator muscles?

To stabilize joints Signup and view all the answers

Which muscle is described as the prime mover when flexing the elbow according to the text?

Brachialis Signup and view all the answers

What is the main role of an antagonist muscle in a muscle group?

To oppose the action of the prime mover Signup and view all the answers

In muscle movements, what is a lever defined as, based on the laws of physics?

A rigid shaft for transferring force Signup and view all the answers

When performing finger extension, what is the function of fixator muscles like flexor carpi radialis and flexor carpi ulnaris?

To stabilize the wrist Signup and view all the answers

Which muscle functions to flex the hip?

Iliacus Signup and view all the answers

What is the common site for injections by doctors in the hip region?

Gluteus maximus Signup and view all the answers

Which muscle is used for propulsion from a sprinter's stance?

Gluteus maximus Signup and view all the answers

Which muscle is not categorized as one of the thigh muscles discussed in the text?

Gluteus minimus Signup and view all the answers

Which category do the posterolateral hip muscles belong to?

Anterior hip muscles Signup and view all the answers

What is the function of the deep hip muscles mentioned in the text?

Rotation of the thigh Signup and view all the answers

Which muscle primarily functions to move the forearm?

Biceps brachii Signup and view all the answers

Which muscle is not involved in shoulder abduction?

Pectoralis major Signup and view all the answers

What muscle extends the elbow?

Triceps brachii Signup and view all the answers

Which muscle is responsible for lateral rotation of the arm?

Infraspinatus Signup and view all the answers

What muscle holds the head of the humerus?

Coracobrachialis Signup and view all the answers

Which muscle is involved in both flexion and extension of the shoulder?

Deltoid Signup and view all the answers

What is a troponin molecule composed of?

One sub-unit that binds to calcium ions, another that binds to actin, and a third that binds to tropomyosin Signup and view all the answers

What is the structure of the myosin myofilament?

An elongated golf club-like shape with heavy and light myosin chains Signup and view all the answers

What is the primary function of the G-actin monomers in F-actin polymer?

Provide an active site for myosin binding Signup and view all the answers

How are the heads of myosin molecules positioned within a myosin myofilament?

Alternating directions on each end of the filament Signup and view all the answers

What is the main role of tropomyosin in the actin myofilament?

Coils around the F-actin strands and provides structure Signup and view all the answers

Which component of the troponin molecule binds specifically to calcium ions?

Sub-unit that binds to calcium ions Signup and view all the answers