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BUILD A PROCESS

Build the cross-bridge cycle

Begin with attached myosin after its power stroke.

Build a process

Use the up and down buttons to build the sequence, then check your reasoning. Some biological events overlap; follow the simplified pathway described here.

  1. 1
    ADP leaves
  2. 2
    Phosphate release and power stroke
  3. 3
    Myosin binds exposed actin
  4. 4
    ATP is hydrolysed
  5. 5
    ATP binds myosin
Read the complete pathway
  1. ATP binds myosin. Myosin loses affinity for actin and detaches.
  2. ATP is hydrolysed. The head is re-cocked with ADP and phosphate retained.
  3. Myosin binds exposed actin. Calcium binding to troponin permits site exposure.
  4. Phosphate release and power stroke. The head pulls actin.
  5. ADP leaves. The head remains attached until another ATP binds.

Explain what you observed

Why can ATP depletion cause persistent attachment?

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Your study notes

Take the next step

Connect this activity with your lesson notes and chapter practice.

Read a related learning guide →Practise Support & Movement →Open the student notes folder ↗

Concepts and sources

Curriculum connections: 9.5. Selected concepts.

Read the supporting source ↗PMDC curriculum ↗

Questions and explanations are original teaching material; these are not official exam questions.

Keep exploring Support & Movement

Sort & explain

Compare bone, cartilage and muscle

Connect tissue structure with mechanical function.

Model

Slide the filaments

Change sarcomere length and inspect A band, I band and overlap.

Sort & explain

Read a sarcomere

Identify the landmarks used to describe contraction.