Cellular Respiration
Making ATP
Cellular Respiration
 Occurs in the mitochondria
 Catabolic reaction to generate ATP from glucose
 Each glucose molecule creates 36 ATP
 38 ATP can be created in some tissues (eg. liver)
Structure of mitochondria
Stages of cellular respiration
1. Glycolysis occurs in the cytoplasm
2. Krebs Cycle occurs in the matrix (fluid in the
mitochondria)
3. Electron transport chain in the membrane of the
mitochondria
The stages of
Glycolysis
 This involves splitting the
glucose molecule into 2
pyruvate molecules
 The glucose is converted to
2 PGAL molecules (this
takes 2 ATP)
 The two PGAL are
converted to two pyruvate
(this gives 4 ATP and
provides 2 hydrogen ions)
Glycolysis
Inputs
Outputs
 Glucose
 2 Pyruvate
 NAD
 NADH
 (2 ATP)
 (2 ADP)
 4 ADP
 4 ATP
Krebs cycle
Krebs cycle
 Before each pyruvate
enters the Krebs cycle it
loses one carbon dioxide
molecule
 The NAD carrier picks up
the hydrogen
 The remaining 2 carbons
bond to Coenzyme A to
enter the Krebs cycle
Krebs cycle (cont.)
 During the Krebs cycle, two
more carbon dioxide
molecules are given off
 A total of 10 hydrogen
molecules are picked up by
NAD and FAD carriers
 Each pyruvate molecule
yields one ATP (meaning 2
per glucose molecule)
Krebs cycle
Inputs
Outputs
 2 Pyruvate
 Coenzyme A
 Coenzyme A
 CO2
 NAD
 NADH
 FAD
 FADH2
 ADP
 ATP
Electron transport chain
Electron transport chain
 The carriers NADH and FADH2 deliver the hydrogen ions
to the inner membrane
 Hydrogen ions pass into the inner membrane, passing
electrons along at the same time
 The hydrogen ions are used to generate 32 ATP through
ATP synthase
 Each oxygen molecule accepts hydrogen ions to create
water as a by-product
Electron Transport Chain
Inputs
 FADH2
 FAD
 NADH
 NAD
 Oxygen
 Water
 ADP
 ATP
ADP to ATP
 ATP ‘carries’ energy in the
form of a bond when the
third phosphate is added
 When energy is released
the third phosphate is
released
 ADP return to the
mitochondria to ‘collect’
energy in the form of a
bond (by becoming ATP)
TOTAL Cellular Respiration
Inputs
Outputs
 Glucose
 Carbon dioxide
 Oxygen
 Water
 Water
 36 ATP
Remember: NAD, FAD and ADP are all carriers, they aren’t used up
by this reaction so you don’t include them in the equation
Summary
Anaerobic respiration
 Occurs in the absence of oxygen
 Generates less ATP (only 2 ATP per glucose molecule)
 Glycolysis occurs however the pyruvate is not processed
further resulting in build up
 Produces lactic acid or ethanol
 Used in industry for fermentation (eg. making alcohol)