The best way to approach these type of questions (worth 8 marks) is to explain everything step by step. This will make it much easier for you to explain under stressful exam situations as well as for the examiner to understand your thought process.
1 - An action potential reaches the end of the motor neuron, triggering the release of Ca to be released from the sarcoplasmic reticulum.
2 - the Ca ions bind to proteins called troponin, which are attached to the tropomyosin proteins of the thin actin filaments of the sarcomere
3 - tropomyosin reveals its binding site on the thin actin filaments
4 - myosin heads of the thick myosin filaments attach to the binding sites on actin, resulting in a cross-bridge
5 - ATP on the myosin heads is hydrolysed, releasing ADP and phosphate
6 - myosin head cocks toward the sarcomere centre - this is called a power stroke
7 - another ATP molecule binds to the myosin head, breaking the cross bridge between myosin heads and actin
8 - the whole process is repeated
One to one online tuition can be a great way to brush up on your Biology knowledge.
Have a Free Meeting with one of our hand picked tutors from the UK’s top universitiesFind a tutor