3.6.3 skeletal muscles as effectors

Question 1

Describe the role of ATP in muscle contraction

Answer 1

5. Hydrolysis of ATP (on myosin heads) causes myosin heads to bend;
6. (Bending) pulling actin molecules;
7. Attachment of a new ATP molecule to each myosin head causes myosin heads to detach (from actin sites);

Question 2

Describe the role of Ca ions in muscle contraction

Answer 2

1. Calcium ions diffuse into myofibrils from (sarcoplasmic) reticulum;
2. (Calcium ions) cause movement of tropomyosin (on actin);
3. (This movement causes) exposure of the binding sites on the actin;
4. Myosin heads attach to binding sites on actin;

Question 3

role of glycogen in skeletal muscle?

Answer 3

1. As a store of glucose
   OR
   To be hydrolysed to glucose;
2. For respiration/to provide ATP;