Electron Transport Chain in Medical Biochemistry
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Questions and Answers

What is the energy source used for ATP synthesis in oxidative phosphorylation?

Energy released by the flow of H+ down its gradient

What is the role of ATP synthase in oxidative phosphorylation?

Coupling energy from H+ flow with ATP synthesis

How many protons are needed for the synthesis of 1 ATP?

4

What is the byproduct of the electron transport chain?

<p>H2O</p> Signup and view all the answers

What is the purpose of the proton gradient in oxidative phosphorylation?

<p>To generate ATP</p> Signup and view all the answers

What is the name of the theory that describes the generation of ATP using a proton gradient?

<p>Chemiosmotic theory</p> Signup and view all the answers

How many ATP are generated from the energy released by NADH?

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

What is the location of ATP synthase?

<p>In the mitochondrial inner membrane</p> Signup and view all the answers

What is the purpose of the electron transport chain?

<p>To generate ATP from the energy released during electron transport</p> Signup and view all the answers

Where is the electron transport chain located in the mitochondria?

<p>On the inner mitochondrial membrane</p> Signup and view all the answers

What percentage of energy is generated from the oxidation of NADH and FADH2?

<p>90%</p> Signup and view all the answers

What is the purpose of inhibitors of the electron transport chain?

<p>To prevent the generation of ATP during electron transport</p> Signup and view all the answers

What is the process by which the energy from NADH and FADH2 is used to produce ATP?

<p>Oxidative phosphorylation</p> Signup and view all the answers

Where does glycolysis take place in the cell?

<p>In the cytosol</p> Signup and view all the answers

What is the byproduct of the complete breakdown of glucose during cellular respiration?

<p>6CO2 + 6H2O + ATP</p> Signup and view all the answers

What is the purpose of the electrochemical gradient generated during electron transport?

<p>To drive ATP synthesis</p> Signup and view all the answers

What is the concentration of H+ called?

<p>proton-motive force</p> Signup and view all the answers

What is the function of ATP synthase molecules?

<p>allow H+ to diffuse back to the matrix</p> Signup and view all the answers

What is the effect of DNP on oxidative phosphorylation?

<p>dissipates gradient</p> Signup and view all the answers

Why can't NADH from glycolysis enter the mitochondrial matrix directly?

<p>Because it's made in the cytosol</p> Signup and view all the answers

What is the function of the glycerol phosphate shuttle?

<p>transfers electrons from cytosolic NADH to the mitochondrial matrix</p> Signup and view all the answers

How many ATP are produced per glucose in muscle and brain cells?

<p>30.0 ATP</p> Signup and view all the answers

What is the name of the shuttle mechanism used in liver and heart cells?

<p>malate-aspartate shuttle</p> Signup and view all the answers

How many ATP are produced per glucose in liver and heart cells?

<p>32.0 ATP</p> Signup and view all the answers

Study Notes

Electron Transport Chain

  • Electron transport chain reduces down to water
  • Sequence of electron transport and carriers involves oxidative phosphorylation
  • Inhibitors of electron transport chain include Antimycin A, rotenone, Sodium azide, CN, and CO
  • Uncouplers include DNP, which shuttles H+ across the inner membrane, dissipating the gradient

Mitochondria

  • Mitochondria have an outer membrane that is relatively permeable and an inner membrane that is permeable only to metabolites with specific transporters
  • Impermeable to NADH and FADH2, but permeable to pyruvate
  • Compartmentalization: Kreb's cycle and β-oxidation occur in the matrix, electron transport chain occurs on the inner membrane, and glycolysis occurs in the cytosol

Stages of Cellular Respiration

  • Stage 3: Electron transport chain and oxidative phosphorylation
  • 90% of energy is from the oxidation of NADH and FADH2
  • Electrons from metabolic reactions are sent to NAD+ and FAD

Electron Transport Chain and Oxidative Phosphorylation

  • Energy released during electron transport is used to transport H+ across the inner mitochondrial membrane, creating an electrochemical gradient
  • Proton motive force: energy released by the flow of H+ down its gradient is used for ATP synthesis
  • ATP synthase: H+ channel that couples energy from H+ flow with ATP synthesis
  • 4 protons are needed for 1 ATP synthesis

Energy Calculations

  • NADH: 10 H+ x 1 ATP = 2.5 ATP
  • FADH2: 6 H+ x 1 ATP = 1.5 ATP

ATP Synthesis

  • Proton-dependent ATP synthase uses the proton gradient to make ATP
  • The process is called chemiosmotic theory
  • ATP synthase molecules allow H+ to diffuse back to the matrix, generating ATP through chemiosmosis

Inhibitors and Uncouplers

  • Atractyloside: ADP/ATP antiporter
  • Oligomycin: ATP synthase
  • DNP: shuttles H+ across the inner membrane, dissipating the gradient

Electrons from Glycolysis

  • NADH made in the cytosol can't get into the matrix of the mitochondrion
  • 2 mechanisms transfer electrons from cytosolic NADH: Glycerol phosphate shuttle and Malate/Aspartate shuttle

Glycerol Phosphate Shuttle

  • Takes place in muscle and brain
  • Each NADH is converted to FADH2 inside the mitochondrion
  • FADH2 produces 1.5 ATP

Malate – Aspartate Shuttle

  • Takes place in liver and heart
  • NADH is oxidized while reducing oxaloacetate to malate
  • Malate crosses the inner membrane into the matrix, passing the electrons back to NAD+, producing NADH
  • NADH yields 2.5 ATP via electron transport

Total ATP Production

  • Muscle and brain: 30.0 ATP (uses glycerol phosphate shuttle)
  • Heart and liver: 32.0 ATP (uses malate aspartate shuttle)

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Description

This quiz covers the electron transport chain, oxidative phosphorylation, and regulation in mitochondria, focusing on medical biochemistry concepts. It's suitable for students of MBG1125. Learn about the sequence of electron transport, carriers, inhibitors, and uncouplers.

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