Stage 2: Pyruvate Oxidation

Products: acetyl-CoA, NADH, CO2, H+ (twice)

• mnm

• Occurs in the mitochondria

Stage 3: The Krebs Cycle

• What is the fate of the original 6 carbon atoms from glucose?

• What are the products of the Krebs cycle that will go on to the electron transport chain?

• What are the products of the Krebs cycle that will be used or expelled immediately?

Homework: pg 115 #’s 1-10

Stage 4: The Electron Transport Chain

• NADH and FADH2 transfer the hydrogen atom electrons they carry to a number of proteins that are embedded in the mitochondrial inner membrane.

• Proteins are arranged in order of increasing electro negativity (weakest to strongest e- acceptors)

• Each protein is reduced (gain 2 e-) then oxidized (lose 2 e-)

• Oxygen (most electronegative) is the final electron acceptor.

• The free energy released is used to pump H+ ions across the membrane from the mitochondrial matrix to the inter-membrane space.

• The ion H+ imbalance creates electrochemical potential energy (like a battery)

• Note that one molecule of FADH2 is used to pump two ions across the membrane, while one molecule of NADH pump three ions across.

• Also, NADH from glycolysis cannot diffuse into the matrix so it must be “shuttled” in.

Chemiosmosis and Oxidative ATP Synthesis

Electrochemical gradient is caused by:

1) higher positive charge (electric)

2) higher concentration of protons (chemical)

Proton-motive force – the “voltage” that moves the protons through an ATPase complex.

ATP is then diffused into the cytoplasm.

Actual Vs. Theoretical value

The actual energy yield value is lower than expected because:

1. Some H+ ions “leak through the phospholipid bilayer.

2. Some H+ ions are used for other cellular activities.

30 ATP per glucose molecule are actually produced.

Efficiency

Metabolic Rate – amount of energy consumed by an organism in a given time.

Basal Metabolic Rate – the minimum amount of energy you need to stay alive.

Homework:

Calculate your BMI online

pg 115 #’s 5-18