Transcript Cellular Respiration

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
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
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)
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
• 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