Cellular Respiration and Energy Production
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Cellular Respiration and Energy Production

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Questions and Answers

What is the net ATP gain from substrate-level phosphorylation during glycolysis?

  • 6 ATP
  • 4 ATP
  • 0 ATP
  • 2 ATP (correct)

    • How many NADH molecules are produced during glycolysis from one glucose molecule?

  • 1
  • 2 (correct)
  • 3
  • 4

    • What is the primary mechanism of ATP production in the electron transport chain?

  • Fermentation
  • Substrate-level phosphorylation
  • Photophosphorylation
  • Oxidative phosphorylation (correct)

    • What is the total ATP yield from one glucose molecule after accounting for shuttle costs?

    <p>30 ATP</p> Signup and view all the answers

    Which phase of cellular respiration directly produces the most ATP?

    <p>Electron Transport Chain</p> Signup and view all the answers

    What role does NADH play in cellular respiration?

    <p>It acts as an electron carrier.</p> Signup and view all the answers

    During substrate-level phosphorylation, where does the energy for ATP production primarily come from?

    <p>Direct phosphorylation from substrates</p> Signup and view all the answers

    In which part of cellular respiration is glucose oxidized?

    <p>Citric Acid Cycle</p> Signup and view all the answers

    What is the primary outcome of the first phase of glycolysis regarding ATP?

    <p>A net gain of two ATP molecules occurs.</p> Signup and view all the answers

    Which of the following accurately describes substrate-level phosphorylation?

    <p>It generates ATP through direct transfer of a phosphate group.</p> Signup and view all the answers

    What is the formula for pyruvic acid produced from glycolysis?

    <p>C3H4O3</p> Signup and view all the answers

    How many molecules of NADH are produced during glycolysis?

    <p>Two molecules</p> Signup and view all the answers

    In glycolysis, what happens to the hydrogen atoms associated with glucose?

    <p>They are bound to NAD+ to form NADH.</p> Signup and view all the answers

    During which phase are the 3-carbon fragments oxidized and ATP is formed?

    <p>Phase 3</p> Signup and view all the answers

    What is the total ATP yield from glycolysis including the consumed ATP?

    <p>Two ATP molecules</p> Signup and view all the answers

    What two byproducts are formed from glucose oxidation that have yet to appear in glycolysis?

    <p>Carbon dioxide and water</p> Signup and view all the answers

    What is the primary product of glycolysis?

    <p>Pyruvic acid</p> Signup and view all the answers

    How many ATP molecules are generated from one NADH + H+ during oxidative phosphorylation?

    <p>2.5 ATP</p> Signup and view all the answers

    Which process involves the formation of glucose from noncarbohydrate precursors?

    <p>Gluconeogenesis</p> Signup and view all the answers

    How much ATP is generally produced from one FADH2 during oxidative phosphorylation?

    <p>1.5 ATP</p> Signup and view all the answers

    What is the total maximum yield of ATP from the complete oxidation of one glucose molecule?

    <p>32 ATP</p> Signup and view all the answers

    Which shuttle mechanism is responsible for transporting NADH electrons into the mitochondria?

    <p>Glycerol phosphate shuttle</p> Signup and view all the answers

    Which of the following statements is true regarding the efficiency of FADH2 in ATP production?

    <p>It donates electrons at a lower energy level in the chain.</p> Signup and view all the answers

    When glycolysis occurs outside the mitochondria, what is the consequence for NADH + H+ production?

    <p>There is an energy cost in transferring electrons to the electron transport chain.</p> Signup and view all the answers

    Study Notes

    Cellular Respiration and Energy Production

    • NADH + H+ and FADH2 are electron carriers that feed into oxidative phosphorylation, generating approximately 28 ATP molecules.

    • Each NADH + H+ molecule generates about 2.5 ATP molecules through the proton gradient.

    • The two NADH + H+ molecules produced during glycolysis yield 5 ATP.

    • The 8 NADH + H+ molecules generated during the transition reaction and the citric acid cycle produce 20 ATP.

    • FADH2 is less efficient than NADH + H+ because it donates electrons to a lower energy level in the electron transport chain (at complex II).

    • Each FADH2 generates around 1.5 ATP, resulting in 3 ATP from the 2 FADH2 molecules produced in the citric acid cycle.

    • The complete oxidation of one glucose molecule to CO2 and H2O through substrate-level phosphorylation and oxidative phosphorylation yields a maximum of 32 ATP molecules.

    • There is uncertainty about the exact ATP yield from the NADH + H+ produced during glycolysis outside the mitochondria.

    • The inner mitochondrial membrane is impermeable to reduced NADH, requiring shuttle molecules to transfer electrons to the electron transport chain.

    • Some shuttles (like the glycerol phosphate shuttle) have an energy cost of 1 ATP per NADH, while others seem to provide a "free ride."

    • Cellular respiration does not result in unlimited ATP synthesis, as cells cannot store large amounts of ATP.

    • Aside from cellular respiration, carbohydrate metabolism focuses on maintaining the right glucose level in the blood, involving three key processes:

      Glycogenesis

      • Polymerizes glucose to form glycogen

      Glycogenolysis

      • Hydrolyzes glycogen to glucose monomers

      Gluconeogenesis

      • Forms glucose from noncarbohydrate precursors

    • Glycolysis, the first stage of glucose metabolism, converts glucose to pyruvate (pyruvic acid).

    • During glycolysis, 4 ATP molecules are produced, but 2 are consumed for activation energy, resulting in a net gain of 2 ATP.

    • Each pyruvate molecule (C3H4O3) contains four hydrogen atoms, whose electrons are bound to two molecules of NAD (NADH).

    • While glycolysis generates some ATP, energy from the remaining products (H2O and CO2) is not harvested until later stages.

    • The energy flow in cellular respiration follows this sequence: glucose -> NADH + H+ -> electron transport chain -> proton gradient energy -> ATP.

    • Substrate-level phosphorylation contributes a net gain of 4 ATP (2 from glycolysis and 2 from the citric acid cycle).

    • Oxidative phosphorylation generates approximately 28 ATP from electron transport chain activity and proton gradient energy.

    • Taking into account potential shuttle costs (2 ATP), the typical ATP yield per glucose molecule is estimated to be 30 ATP.

    • The proton gradient is also used for other cellular processes, so the actual ATP yield may be less than 30 ATP.

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    Description

    Test your understanding of cellular respiration and the ATP yield from NADH and FADH2. This quiz covers the processes of oxidative phosphorylation and substrate-level phosphorylation in detail. Learn how glucose oxidation leads to energy production in cells.

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