Question

1. adenosine triphosphate (atp) plays what role in muscle contraction?

a. the molecule that attaches to troponin and moves actin out of the way.
b. the molecule that causes myosin to move in towards actin.
c. the molecule that causes myosin to move out of the way on the actin.
d. the molecule that causes myosin heads to detach from actin.

1. calcium plays what role in muscle contraction?

a. the molecule that attaches to troponin and moves tropomyosin out of the way.
b. the molecule that causes myosin heads to detach from sarcomeres.
c. the molecule that cases myosin to move in towards actin.
d. the molecule that causes the sarcomere to attach to myosin heads.

1. match the muscle types to their correct cellular structure by drawing a line.

smooth muscle cardiac muscle skeletal muscle

1. match the same muscle types to what the muscle controls and where it can be found in the body.

smooth muscle ____ found throughout the body, allowing us to move.
cardiac muscle ____ found in the heart, involuntary movement.
skeletal muscle ____ found in organs, involuntary movement.

1. what is the big idea behind the sliding filament theory of muscle contraction?

a. during contraction actin moves in towards myosin, causing the sarcomere to shorten.
b. during contraction myosin shrinks due to actin, causing the sarcomere to shorten.
c. during contraction myosin heads pull on troponin, causing the sarcomere to shorten.
d. during contraction calcium connects to z - lines, causing the sarcomere to shorten.

Explanation:

1. ATP in muscle contraction:

• ATP binds to myosin heads. When it is hydrolyzed (broken down), it provides the energy for the myosin heads to detach from actin. After detachment, the myosin heads can re - attach to a new position on actin.

1. Calcium in muscle contraction:

• Calcium (\(Ca^{2+}\)) is released from the sarcoplasmic reticulum. It binds to troponin. This binding causes a conformational change in troponin, which then moves tropomyosin out of the way. This exposes the binding sites on actin for myosin.

1. Muscle types and cellular structure:

• Smooth muscle: Has a non - striated appearance. The cells are spindle - shaped.
• Cardiac muscle: Has a striated appearance (due to the arrangement of actin and myosin filaments) and is branched.
• Skeletal muscle: Has a highly striated appearance and is multinucleated.

1. Muscle types and their locations/functions:

• Smooth muscle: Found in organs (e.g., the digestive tract, blood vessels). It is involuntary (not under conscious control).
• Cardiac muscle: Found only in the heart. It is involuntary.
• Skeletal muscle: Found throughout the body attached to bones. It is voluntary (under conscious control) and allows for movement.

1. Sliding Filament Theory:

• The basic idea is that during muscle contraction, actin filaments slide over myosin filaments. Myosin heads bind to actin, undergo a power stroke (a conformational change that pulls actin), and then detach (using ATP). This repeated cycle causes the sarcomere (the basic unit of muscle contraction) to shorten.

Answer:

1. d
2. a
3. Smooth muscle - non - striated, spindle - shaped; Cardiac muscle - striated, branched; Skeletal muscle - highly striated, multinucleated
4. Smooth muscle - Found in organs, involuntary movement; Cardiac muscle - Found in the heart, involuntary movement; Skeletal muscle - Found throughout the body, allowing us to move
5. a