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. H + is pumped into the inter mitochondrial membrane space creating the “proton motive force”

2. 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

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 ATPif completely efficient it could create 38 ATP

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

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