Cellular RespirationHow Cells Harvest Chemical Energy Cellular
C6H12O6 + 602 6CO2 + 6H20
A catabolic pathway
Oxygen is consumed as a reactant along with organic
Involves three stages:
GlycolysisKrebs CycleElectron Transport Chain
What Is ATP?Adenosine Triphosphate
Energy used by all Cells
Organic molecule containing high-energy Phosphate bonds
Chemical Structure of ATP
What Does ATP Do for You?It supplies YOU with ENERGY!
How Do We Get Energy From ATP?By breaking the high- energy bonds
between the last two phosphates in ATP
NADH and FADH2NAD+ traps electrons from glucose to make NADH
Similarly, FAD+ stores energy as FADH2
Where Does Cellular Respiration Take Place?It actually takes
place in two parts of the cell:
Glycolysis occurs in the CytoplasmKrebs Cycle & ETC Take
place in the Mitochondria
Review of Mitochondria StructureSmooth outer MembraneFolded
inner membraneFolds called CristaeSpace inside cristae called the
Diagram of the ProcessOccurs in CytoplasmOccurs in MatrixOccurs
Glycolysis 1. Means splitting of sugar
2. Occurs in the cytosol of the cell
3. Partially oxidizes glucose (6C) into two pyruvate (3C)
4. Occurs whether or not oxygen is present.
5. An exergonic process, (meaning energy is released) most of
the energy harnessed is conserved in the high-energy electrons of
NADH and in the phosphate bonds of ATP
Glycolysis SummaryTakes place in the CytoplasmAnaerobic (Doesnt
Use Oxygen)Requires input of 2 ATPGlucose split into two molecules
of PyruvateAlso produces 2 NADH and 4 ATP
Formation of Acetyl CoA1. Junction between glycolysis and Krebs
2. Oxidation of pyruvate to acetyl CoA
3. Pyruvate molecules are translocated from the cytosol into the
mitochondrion by a carrier protein in the mitochondrial
4. A CO2 is removed from pyruvate making a 2C compound.
5. Coenzyme A is attached to the acetyl group.
Formation of Acetyl CoA
Formation of Acetyl CoA
Krebs CycleRequires Oxygen (Aerobic)Cyclical series of oxidation
reactions that give off CO2 and produce one ATP per cycleTurns
twice per glucose moleculeProduces two ATP Takes place in matrix of
Krebs Cycle SummaryEach turn of the Krebs Cycle also produces
3NADH, 1FADH2, and 2CO2
Therefore, For each Glucose molecule, the Krebs Cycle produces
6NADH, 2FADH2, 4CO2, and 2ATP
Electron Transport Chain 1. Located in the inner membrane of the
2. Oxygen pulls the electrons from NADH and FADH2 down the
electron transport chain to a lower energy state. 3. Process
produces 34 ATP or 90% of the ATP in the body.
Electron Transport Chain4. Requires oxygen, the final electron
5. For every FADH2 molecule 2 ATPs are produced.
6. For every NADH molecule 3 ATPs are produced.
7. Chemiosmosis the production of ATP using the energy of H+
gradients across membranes to phosphorylate ADP.
ATP SynthaseA protein in the inner membrane in the
Uses energy of the ion gradient to power ATP synthesis.
For every H+ ion that flows through ATP synthase, one ATP can be
formed from ADP
Cellular Respiration in Summary Glycolysis2 ATP2 NADH 4-6 ATP
(Depends on how this NADH molecule gets to the ETC. To make things
simple we will say that these two NADHs make 4 ATP )Formation of
Acetyl CoA2 NADH 6 ATP
Cellular Respiration in SummaryKrebs Cycle2 ATP6 NADH 18 ATP2
FADH2 4 ATP
Grand Total = 36 ATP
FermentationOccurs when O2 NOT present (anaerobic)Called Lactic
Acid fermentation in muscle cells (makes muscles tired)Called
Alcoholic fermentation in yeast (produces ethanol)Nets only 2