Cellular Respiration Process by which cells extract energy from food Literally it’s about using bond energy (electrons) to regenerate ATP May be anaerobic

Cellular Respiration

• Process by which cells extract energy from food

• Literally it’s about using bond energy (electrons) to regenerate ATP

• May be anaerobic or aerobic

C6H12O6 + 6O2 6CO2 + 6H2O

Aerobic Respiration as a 3-Act Play

• Act I: Glycolysis

• Act II: The Kreb’s Cycle

• Act III: Oxidative Phosphorylation and the Electron Transport Chain

Glycolysis

• 6C glucose split

• to 2, 3C pyruvates

• Yield 2 ATP

• Yield 2 NADH

• 10 reaction steps,

each catalyzed by

specific enzymes.

What’s the point of glycolysis?

• The key point of glycolysis is that all cells, without even using oxygen, are able to make food monomers reactive enough to split down to pyruvate. The pyruvate molecules then proceed to further steps that extract much more energy from the bonds.

“The fate of pyruvate”

• In anaerobic conditions, it is converted to lactic acid or ethanol, with a yield of 4 ATP/glucose

• In aerobic conditions, it enters the mitochondria, proceeds through Kreb’s Cycle and Oxidative Phosphorylation at the ETC for yield of 36 ATP/glucose





Kreb’s Cycle (aka Citric Acid Cycle)

A metabolic “furnace”

that oxidizes pyruvate

fuel.

Each pyruvate is broken

down to 3 CO2.

2 pyruvates 2 ATP

6 NADH

2 FADH2

What’s the point of Krebs Cycle?

• The point of the Krebs cycle is to reduce coenzymes.

• In Krebs, NAD+ and FAD are reduced to NADH & FADH2 from the oxidation of pyruvate (or actually, Acetyl, CoA).

• The reduced coenzymes, NADH & FADH2 act as electron taxi cabs, shuttling their key passengers to the cristae.

Mitochondria Anatomy Review

Remember:

Glycolysis -- in cytosol

Krebs -- in mito matrix

Ox Phos –at mito cristae

(in the “electron transport chain” ETC)





• Chemiosmosis simulation

Oxidative Phosphorylation and the Electron Transport Chain

What’s the point of oxidative phosphorylation at the ETC?

• The electrons, originally from glucose, are delivered to the ETC by NADH and FADH2, and are passed down the ETC.

• This “electrical energy” runs a molecular machinery that pumps protons across the cristae.

• These protons pass back through the cristae at the ATP synthase enzyme, regenerating ATP!

Review of Cells & Metabolism

• Enzymes & Activation Energy• ATP and coupled reactions• Cellular Respiration

– Glycolysis• Anaerobic fermentation or lactic acid formation• Aerobic, proceed to below

– Krebs Cycle– Ox. Phos. & the ETC

Documents

Cellular Respiration Process by which cells extract energy from food Literally it’s about using bond energy (electrons) to regenerate ATP May be anaerobic