During muscle contraction, energy is provided by (a). acetyl-CoA (b). Phosphagen (c). AMP (d). Glucose?

Question

Answer

In the resting muscle, creatine combines with phosphoric acid to form phosphagen . When the muscle contract phosphagen splits back into creatine and phosphoric acid, with the release of energy. This energy is responsible for the actual muscle contraction.so, correct option is B.

Answer

Phosphocreatione (PC) ...phosphogen  is a high. energy phosphoric ester that serves as a reservoir of phosphocreatione in vertebrates ...

Answer

During muscle contraction, energy is primarily provided by glucose, which is broken down through several metabolic pathways to generate ATP (adenosine triphosphate), the energy currency of the cell. The process involves the conversion of glucose to pyruvate through glycolysis, followed by further breakdown in the mitochondria.

Glucose Metabolism in Muscle Contraction:

1. Glycolysis:
- Glycolysis occurs in the cytoplasm and is the initial step in glucose metabolism. It involves the breakdown of glucose into two molecules of pyruvate, producing a small amount of ATP and NADH in the process.
- The ATP produced during glycolysis is readily available for immediate use by the contracting muscles.

2. Pyruvate Conversion:
- Pyruvate is transported into the mitochondria where it undergoes further breakdown.
- Pyruvate is converted into acetyl-CoA, a key molecule in the citric acid cycle (also known as the Krebs cycle or TCA cycle).

3. Citric Acid Cycle:
- The citric acid cycle occurs in the mitochondria and involves a series of chemical reactions that further break down acetyl-CoA.
- During this cycle, high-energy electrons are transferred to electron carriers (NADH and FADH2), which will later enter the electron transport chain.

4. Electron Transport Chain:
- The electron transport chain is located on the inner mitochondrial membrane and is responsible for the majority of ATP production.
- Electrons from NADH and FADH2 are transferred through a series of protein complexes, generating a proton gradient across the membrane.
- This proton gradient is used to drive ATP synthesis through the enzyme ATP synthase.

5. ATP Production:
- ATP synthase utilizes the energy from the proton gradient to convert ADP (adenosine diphosphate) to ATP.
- This process, known as oxidative phosphorylation, generates the majority of ATP during muscle contraction.

Other Energy Sources:

While glucose is the primary energy source during muscle contraction, other energy sources can be utilized under certain conditions:

- Phosphagen System: Phosphocreatine (PCr) is a high-energy molecule stored in muscle cells. It can rapidly donate a phosphate group to ADP, forming ATP, during intense muscle contractions. This system provides a quick burst of energy but is limited in duration.

- Acetyl-CoA: Acetyl-CoA can also be derived from other fuel sources, such as fatty acids and amino acids, through various metabolic pathways. However, these pathways are not as efficient for quick energy production during muscle contraction compared to glucose metabolism.

Conclusion:

During muscle contraction, glucose is the primary energy source. It undergoes glycolysis to produce ATP in the cytoplasm, followed by further breakdown in the mitochondria through the citric acid cycle and electron transport chain. This process efficiently produces ATP to meet the energy demands of muscle contraction. However, under certain conditions, the phosphagen system and other fuel sources like acetyl-CoA can contribute to energy production.

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