Muscle

Question 1

Contraction of skeletal muscle - sliding filament mechanism

Answer 1

1. Muscle stimulation, action potential travels deep into fibre via T tubles
2. Tropomyosin molecule prevents myosin head from attaching to binding site on actin molecule
3. Calcium ions released from the endoplasmic reticulum causes tropomyosin molecule to change shape, pull away from binding sites on actin molecule
4. Myosin head now attached to binding sites on actin filament (cross bridge)
5. Head of myosin changes angle, moves actin filament along, ADP molecule released
6. ATP molecule fixes to myosin head, causes it to detach from actin filament
7. Hydrolysis of ATP to ADP by ATPase, provides energy for the myosin head to return to normal position
8. Head of myosin reattached to binding site further along actin filament, the cycle is repeated