What is the role of ATP and ATP hydrolysis in the cycle of actin-myosin associat
ID: 481122 • Letter: W
Question
What is the role of ATP and ATP hydrolysis in the cycle of actin-myosin association and dissociation that leads to muscle contraction? Methanol (wood alcohol) is highly toxic because it is converted to formaldehyde in a reaction catalyzed by the enzyme alcohol dehydrogenase. NAD^+ + methanol rightarrow NADH + H^+ formaldehyde Part of the medical treatment for methanol poisoning is to administer ethanol(ethyl alcohol) in amounts large enough to cause intoxication under normal circumstances. Explain this in terms of what you know about examples of enzymatic reactions. When a vertebrate die, its muscles stiffen as they are deprived of ATP, in a state called rigor mortis. Explain the molecular basis of the rigor state. What ii the chemical basis for enzyme specificity? Briefly explain the meaning of K_s and K_x, and explain what they each measure, which one measure affinity of the enzyme complex?Explanation / Answer
The free energy of ATP hydrolysis is translated into a conformational change in the myosin head, so dissociation of myosin and actin , hydrolysis of ATP and rebinding of myosin and actin occur due to hydrolysis of ATP.
Ans 2:
Ethanol is a structural analog of methanol, and competes with methanol for the binding site of alcohol dehydrogenase, thus slowing down the conversion of methanol to formaldehyde, and allowing its clearance by the kidneys. The effect of ethanol is that of a COMPETITIVE INHIBITOR.
Ans 3:
Muscle cell membrane proteins use ATP to actively pump the calcium ions back out of the cell, restoring the membrane potential and preventing the calcium ions from re-stimulating contraction.
When breathing and circulatiom stop, muscle cells lack oxygen and therefore cannot use aerobic respiration to efficiently produce ATP. Respiration continues anaerobically at first, but the muscle cells eventually become ao short of ATP that the myosin and actin filaments cannot release from the contracted state anf the calcium ions cant be pumped back out of the muscle cell.
Unable to release contraction, all the muscles of the body remain tense, causing RIGOR MORTIS.
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