Question

The correct sequence of events occurring during the contraction of skeletal muscle is:
A. Troponin-Calcium complex uncovers active sites on actin
B. Linking of actin and myosin filaments
C. Action of ATPase for providing energy
D. Depolarisation of the Sarcolemma and T tubules
E. Release of Calcium ions
Choose the correct answer from the options given below:

• A. C, B, A, D, E
• B. D, A, E, B, C
• C. D, E, A, B, C
• D. D, E, A, C, B

Hint:

Depolarize → Calcium → Actin exposed → Cross-bridge → Contraction

Answer 1

The Correct Option is C

Concept:
Skeletal muscle contraction follows excitation-contraction coupling, where electrical signals lead to mechanical contraction.

Step 1: Initiation – depolarisation.

• Nerve impulse causes depolarisation of sarcolemma
• Signal travels through T-tubules Thus: \[ D: Depolarisation \]

Step 2: Calcium release.

• Depolarisation triggers sarcoplasmic reticulum
• Calcium ions are released Thus: \[ E: Release of Calcium ions \]

Step 3: Exposure of binding sites.

• Calcium binds to troponin
• Tropomyosin shifts exposing actin sites Thus: \[ A: Troponin-Calcium complex \]

Step 4: Cross-bridge formation.

• Myosin heads attach to actin Thus: \[ B: Linking of actin and myosin \]

Step 5: Power stroke.

• ATPase provides energy
• Contraction occurs Thus: \[ C: Action of ATPase \]

Step 6: Final sequence.
\[ D \rightarrow E \rightarrow A \rightarrow B \rightarrow C \] \[ \boxed{\text{Correct answer = Option (3)}} \]