The Aerobic Reaction
Krebs Cycle & Electron Transport Chain
Products of Glycolysis
●
●
●
●
2 pyruvic acids
2 NADH
2 net ATP
Pyruvic acids and NADH go to the
mitochondria
○ Pyruvic acids move to mitochondrial
matrix
○ NADH goes to the electron transport
chain
Krebs Cycle
● Breaks pyruvic acid down to
CO2 & creates energy-storing
molecules
● Occurs in the mitochondria’s
matrix
● Also known as the citric acid
cycle
Krebs Cycle
● Pyruvic acid has 3 carbon
atoms
● One C atom is removed and
becomes CO2
● The two remaining C atoms
join with coenzyme A to form
acetyl-CoA
● NADH is also made
Krebs Cycle
● Acetyl-CoA bonds with a 4-C
molecule, becomes citric acid
(6C)
● Through many steps, citric acid
loses 2 carbon atoms
○ Carbon atoms form CO2
○ High-energy electrons are
used to create ATP, NADH,
and FADH2
Krebs Cycle Products
● Each pyruvic acid creates:
○ 3 CO2
○ 4 NADH
○ 1 FADH2
○ 1 ATP
Krebs Cycle Products
● Since there are two pyruvic acids,
the total products are:
○ 6 CO2 (breathe out)
○ 8 NADH (goes to ETC)
○ 2 FADH2 (goes to ETC)
○ 2ATP (used as energy)
● The 4-C molecule goes back to
join with another Acetyl-CoA...it’s
a cycle!
Electron Transport Chain
● Uses high-energy
electrons from Krebs
cycle to turn ADP into
ATP
● Occurs on the inner
membrane of
mitochondria
Electron Transport Chain
● NADH & FADH2
break down into
NAD+ and FAD
● High-energy electrons
are released and travel
through proteins in the
inner membrane
Electron Transport Chain
● As electrons travel,
their energy pumps H+
ions into the
intermembranous
space.
● Electrons bond with
H+ and O2 to form
H2O
Electron Transport Chain
● The high concentration
of H+ wants to move
back into the matrix
● H+ pass through ATP
synthase, creating ATP
ETC Products
● About 32 ATP
● 6 H2O
Total Products of Cellular Respiration
● Glycolysis: 2 net ATP
● Krebs Cycle: 2 ATP, 6 CO2
● ETC: 32 ATP, 6 H2O
● TOTAL: 36 ATP
● 36 ATP is 38% of the total energy in glucose
○ excess is lost as heat
○ more efficient than a car