181 E Exam#5 mheducation.com/tlow/connect.htm #50 Help Required information Once

Question

181 E Exam#5 mheducation.com/tlow/connect.htm #50 Help Required information Once tissues die they cease the production of ATP. which is the molecule required to detach myosin crossbridge heads from a the absence of ATP, the breakage of the link between actin and myosin does not occur, and the thick and thin myo laments ren bound to each other in an immobilized, rigid fashion. Rigor mortis persists unti the muscle tissue decomposes 3 of 3 1 The presence of calcium in the sarcoplasm is directly responsible for O exposing the binding sites on actin O decreasing the length of the myosin myofilament the movement of actin towards the M line O energizing the myosin heads 00 3019 2. Rigor mortis occurs after death because O detachment of crossbridges does not occur due to the lack of ATP O actin binding sites become permanently blocked so that crossbridge formation cannot occur O the power stroke becomes stronger after death no calcim is present to bind to the regulatory protein tropomyosin

Explanation / Answer

1.(a) The presence of Calcium in the sarcoplasm is directly responsible for exposing the binding sites on actin. What happens is that Calcium binds to troponin which exposes the binding sites on Actin filaments. This Myosin heads binds at this site because it is attracted to actin.

2.(a) Rigor mortis occurs after death because detachment of crossbridges does not occur due to the lack of ATP. When Mysoin is attracted to actin and binds with the actin filaments then it forms a cross bridge. This cross bridge can be separated only using ATP and in this case there is lack of ATP because of the diminishing glycogen. This leads to rigor mortis after death.

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