Question

learning target: ap.5.3 - explain the molecular processes involved in the sliding filament model and biochemical mechanisms that provide energy for muscle contraction and relaxation.
instructions:
complete the following sentences and answer the questions related to muscle contraction. completing the muscle contraction interactive bioman game will help you.

1. when a nerve impulse reaches a muscle, it causes ____________ to be released.
2. calcium ions cause __________ to change shape and move ________ so that it no longer blocks myosin binding sites on __________.
3. troponin causes __________ to move, so that __________ can bind to actin.
4. what structure is formed when the myosin head binds to an actin filament during muscle contraction?
5. what form of energy is needed to drive a muscle contraction?
6. what is the first role of atp in a muscle contraction?
7. how does atp release its stored energy?

Explanation:

1. When a nerve impulse reaches a muscle, it causes calcium ions to be released. This is a key step in initiating muscle contraction as calcium is crucial for the subsequent events in the sliding filament model.
2. Calcium ions cause troponin to change shape and move tropomyosin so that it no longer blocks myosin binding sites on actin. Troponin - tropomyosin complex plays a regulatory role in muscle contraction.
3. Troponin causes tropomyosin to move, so that myosin can bind to actin. This binding is essential for the power stroke in muscle contraction.
4. When the myosin head binds to an actin filament during muscle contraction, a cross - bridge is formed. Cross - bridges are responsible for the sliding of filaments.
5. The form of energy needed to drive a muscle contraction is chemical energy in the form of ATP (adenosine triphosphate). ATP provides the energy for the movement of myosin heads.
6. The first role of ATP in a muscle contraction is to bind to the myosin head and cause it to detach from actin. This is part of the cross - bridge cycle.
7. ATP releases its stored energy by breaking the bond between its second and third phosphate groups, forming ADP (adenosine diphosphate) and inorganic phosphate.

Answer:

1. calcium ions
2. troponin; tropomyosin; actin
3. tropomyosin; myosin
4. cross - bridge
5. chemical energy (ATP)
6. to bind to the myosin head and cause it to detach from actin
7. by breaking the bond between its second and third phosphate groups, forming ADP and inorganic phosphate