3.6.6: Muscle structure and contraction Describe the roles of ATP in musc Flashcards
1
Q
Describe the roles of ATP in muscle contraction.
A
- To break actinomyosin (bridges);
- To move/bend the myosin head/arm;
- (So) actin (filaments) are moved (inwards);
- For active transport of calcium ions (into the sarcoplasmic/endoplasmic reticulum);
2
Q
Explain how a decrease in the concentration of
calcium ions within muscle tissues could cause a
decrease in the force of muscle contraction.
A
- (Less/No) tropomyosin moved from binding site
OR
Shape of tropomyosin not changed so binding site not exposed/available;
Ignore troponin.
Reject active site only once. - (Fewer/No) actinomyosin bridges formed;
Accept actin and myosin do not bind.
Reject active site only once. - Myosin head does not move
OR
Myosin does not pull actin (filaments)
OR
(Less/No) ATP (hydrol)ase (activation);
Reject ATP synthase.
Do not penalise reference to calcium rather than calcium ions.
Credit all mark points even if context relates to what happens when calcium
ions are present.