Light energy* Chemical bond energy (ATP*)

Energy is stored in the chemical bonds of glucose

ATP* hydrolysis ADP + Pi + energy*

6CO2 + 12H2O (H source) + energy* glucose*

To synthesize organic molecules, it takes energy and reducing power.

ATPSource of attachable H.

To retrieve energy from glucose:1. strip away high energy electrons from the chemical bonds of glucose2. this is oxidation (loss of electrons)

3. cellular respiration is a two-step process:remove electronsuse the energy in those electrons

Glycolysisoccurs in the cytoplasm of all living organismsenzymatic splitting of glucoseyields 2 pyruvatesnet gain of 2 ATP and 2 NADH*

Substrate-level phosphorylationNet gain of 2 ATP per glucose

2 electrons removed and carried on NADH x2

Pyruvate oxidized (by NAD+)One C removed as CO2

Coenzyme A is addedLeaves acetyl-CoA

Acetyl-CoA can have many fates:ATP synthesis (in mitochondrial matrix)fat synthesis lipid synthesis amino acid synthesis

2 CO2

3 NADH1 FADH2

1 ATP

original 4-C sugar

Electron Transport System

Photosynthesis vs. Cellular Respiration

source of high-energy electronsused electrons cannot be recycled in mitochondria

Net results

ATP production decreases when ATP is plentiful.

Animal cells convert pyruvate to lactic acid in the absence of O2

Makes NAD+ available so glycolysis can continue

Yeast cells convert pyruvate to ethanol in the absence of O2