Electron Transport Chain
• The energy stored in the carrier molecules
NADH and FADH2 are extracted in the
electron transport chain (ETC) to produce
the majority of the ATP in the
membranous matrix of the mitochondria.
As the carriers (NAD+ & FAD) move down
the chain they alternate between oxidized
and reduced states passing the e- to
increasingly electronegative carriers.
1.
As the electrons are passed down the
chain the energy is harvested to create
the H + gradient necessary for producing
ATP
1.
2.
H + is pumped into the inter mitochondrial
membrane space creating the “proton
motive force”
The final electron acceptor of the chain
passes the used H + to O to form H2O
1. Makes no ATP
2. Manages electrons and
removes them to be used in
next step
3. Pushes H+ ions to the inner
membrane establishing the
ion gradient (from NADH &
FADH2)
4. Forms H2O at the end of the
chain
ATP Synthesis
(Oxidative Phosphorylation)
• ATP is synthesized by the protein (enzyme) ATP
synthase that is found in the mitochondrial
membrane.
– ATP synthase harvests the energy of the proton
gradient to produce ATP via oxidative
phosphorylation.
• Uses existing ion gradient (H+ ions) established
through the ETC
– uses H+ ions concentrated in the intermembrane
space (proton-motive force) to generate ATP as
they flow through ATP synthase in the
mitochondrial membrane.
• simply put...uses H+ ions stored in the form of a
gradient to do cellular work
• Movement of ions through the inner channel causes
the production of ATP from ADP
– The spent (electron poor) H + ions join with O2 to
form H2O
Cellular Respiration
Summary
Citric Acid Cycle
changes pyruvate into Acetyl CoA
then to citrate
cycles ultimately modifying citrate
into the beginning molecule
Oxaloacetate
8 NADH (2 from process of
changing pyruvate to Acetyl CoA)
2 FADH2
6 CO2 (2 from process of
changing pyruvate to Acetyl CoA)
2ATP
Glycolysis
changes glucose-6-phosphate
to 2 pyruvate molecules
2 NADH
2 ATP
Oxidative Phosphorylation
uses energy stored in the
electron carriers and the
proton-motive force to
product ATP
32 or 36 ATP
if completely
efficient it could
create 38 ATP
Using Energy
• ATP used 1st!
– The muscles will empty the stores of ATP
within a few seconds
– ATP production replaces the ATP void
• Lactic acid fermentation… fast production
– Very inefficient
• Oxidative phosphorylation (cellular respiration)
– Slower but more efficient
» Uses glycogen stored in muscles
» Myoglobin… oxygen carrying molecule similar
to hemoglobin found in red blood cells
– Other sources of carbon material
» Liquid fats (oils)
» Lipids stored in adipose (fat) cells
» Protein stored in muscles
Source of
substrates
•
•
Storage
increased with
frequent need
The muscles
become more
efficient with
frequent use