Correctly relate the story of contraction events in order in…

Cоrrectly relаte the stоry оf contrаction events in order in а muscle fiber by numbering each event below. 1.  Troponin changes shape. 2.  Calcium ions bind to troponin. 3.  Myosin heads bind to active sites on actin molecules. 4.  Tropomyosin moves and exposes the active sites on the actin molecules. 5.   Cycling continues until calcium ions are taken back into the sarcoplasmic reticulum. 6.   Myosin heads pull on thin myofilaments and slide them toward the center of the sarcomere.