Respond to the following questions. Your answers should not be more than one par

Question

Respond to the following questions. Your answers should not be more than one paragraph each. Make sure that your answers are complete. The questions are:
Explain how cellular respiration releases chemical energy.

Respond to the following questions. Your answers should not be more than one paragraph each. Make sure that your answers are complete. The questions are:
Explain how cellular respiration releases chemical energy.

Respond to the following questions. Your answers should not be more than one paragraph each. Make sure that your answers are complete. The questions are:
Explain how cellular respiration releases chemical energy.

Explanation / Answer

Cellular respiration involves series of steps in which the biochemical energy stored in biomolecules in the form of bonds is being released and converted to ATP which is the energy source of the plants and animals. Glucose is a major fuel of most organism, relatively rich in potential energy. Its complete oxidation to CO2 and H2O yields 686 kcal energy/mol.

In physiological respiration there is uptake of O2 and release of CO2. Similarly in cellular respiration in terms of microscopic sense molecular processes involved O2 consumption and CO2 formation during TCA cycle. It is of two types A) Aerobic {in the presence of oxygen}; B) Anaerobic {in the absence of oxygen}.

The very first step in cellular respiration is conversion of one molecule of glucose into two molecules of pyruvate in the absence of oxygen in the cell cytoplasm. In a complete 10 steps of reaction their is a net gain of 2 ATPmolecules. Overall 4ATP molecules are produced and 2ATPs get utilized, therefore net gain of 2ATP. During the whole series of glycolytic reactions 2NADH2 molecules (reducing power, electron carriers) are also produced which on oxidative phosphorylation (reaction which takes place in the presence of oxygen in mitochondria) forms additional 3ATP, overall 6ATP from 2 molecules. The pyruvate thus formed under aerobic conditions is oxidized (oxidative decarboxylation) and forms 2C compound acetyl Coenzyme A with a release of one molecule of CO2 (overall 2). Again from 2 pyruvate molecules 2 NADH2 molecules are produced which on oxidative phosphorylation forms 6ATP. The acetyl CoA now enters mitochondria and there in a cyclic process known as TCA cycle or citric acid cycle or Krebs cycle is completely oxidized to CO2 and H2O in 8 steps.In whole TCA cycle 6NADH2, 2FADH2 and 2ATPs are formed.Thus overall

2ATP from glycosis. 6ATP from oxidative phosphorylation from glycosis, 6ATP from oxidative decarboxylation of pyruvate, 18ATP from NADH2, 4ATP from FADH2 and 2 ATP from substrate level phosphorylation in TCA. So there is an overall gain of 38ATP/glucose.

38x30.5kJ/mo (standard free energy change) l=1160kJ/mol 40% of the theoritical maximum of 2840kJ/mol.

In mitochondria electron carriers NADH2 and FADH2 transfer electrons to O2 which ultimately generates 3ATP/pair of electrons.

So first of all energy stored in glucose molecule is converted to energy currency ATP which on availability breaks down to ADP releasing 30.5kJ/mol.

Related Questions

Navigate

• Browse (All)
• Browse R
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.