SME
Human Anatomy & Physiology · Problem type
The cross-bridge cycle in order
Use this for “Put these in order: the power stroke, ATP binding myosin, Ca²⁺ binding troponin, the head recocking.”
Put in order
Put the steps of one cross-bridge cycle in order, from the calcium signal.
1
?
2
?
3
?
4
?
5
?
Assumptions
•
The cycle is one myosin head’s; thousands of heads cycle out of step, so the filaments slide smoothly.
•
It repeats while Ca²⁺ stays bound and ATP lasts, and each stroke pulls actin toward the sarcomere’s center.
•
Without ATP the heads cannot let go of actin: this is rigor mortis.
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