18. Under what condition is cellular respiration impossible? What alternative me
ID: 195458 • Letter: 1
Question
18. Under what condition is cellular respiration impossible? What alternative metabolic process can be used to produce ATP from glucose? Describe this metabolic pathway and indicate how much ATP is produced. 19. Explain substrate-level phosphorylation and oxidative phosphorylation. What is the primary difference between the two processes? 20. No chemical reaction is 100% efficient but how efficient is cellular respiration. The energy available in i mole of glucose is 686 kcal. Cellular respiration is able to produce 32 moles ATP from 1 mole glucose, and ATP contains 7.3 kcal per mole. How much energy (kcal) is converted to ATP during cellular respiration per mole of glucose? What percentage of energy from the original glucose is still available for use as ATP? 21. How much energy is converted to ATP during fermentation? What percentage of energy from the original glucose is still available for use as ATP?Explanation / Answer
20. 1 mol ATP=7.3 KCAL so 32 ATP=32×7.3=233.6 kcal
Original energy present 686 kcal I. e 34% energy converted into 32 ATP Still 66% energy is used as an ATP.
21.During Fermentation 2 ATP formed means 2×7.3=14.6 kcal energy produced. This percentage will be 2% it means still 98% energy is used as an ATP.
19.
Substrate level phosphorylation is when ADP is converted to ATP by the direct transfer of a phosphate group. The phosphate group is donated or transfered from a phosphorylated intermediate. This is in contrast to oxidative phosphorylation, where a chemiosmotic gradient is used to power the phosphorylation process.
A simple way to think of the difference is that in substrate level, the phosphorylation is a direct process, with no middle man. The phosphate comes off of one molecule (the intermediate) and is directly transfered to another (the ADP). The energy for the phosphorylation of ADP is provided directly from breaking the high energy phosphate bond on the intermediate molecule. This is referred to as reaction coupling.
Oxidative phosphorylation has middle men in the form of NADH and the electron transport enzymes. The phosphate comes from a pool of inorganic phosphates instead of directly from another molecule, and the energy to phosphorylate the ADP comes from the proton gradient, not from coupled reactions.
The most famous examples of substrate level phosphorylation are found in the glycolysis pathway. The ATP are produced in the pay off phase of glycolysis by the action of the enzymes phosphoglycerate kinase and pyruvate kinase. Another example of the process is seen in the phosphocreatine pathway, and the enzyme responsible is creatine phosphokinase.
18.
If there isn't any oxygen available, cellular respiration cannot take place. Fermentation is used in place of cellular respiration and occurs in two types - lactic acid fermentation and alcohol fermentation. Both of these processes result in the creation of 2 ATP for every mole of glucose but have different end products as their name suggests.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.