Biology - Chapter 7 - How Cells Harvest Chemical Energy

How Cells Harvest Chemical Energy; Cellular Respiration

The main pathway for energy release from the carbohydrate to ATP; oxygen serves as the ultimate hydrogen acceptor. C₆H₁₂O₆ + 6O₂ + H₂O ---> 6CO₂ + 7H₂O + 36 ATP

The release of lesser amounts of energy for transfer to a small number of ATP; some inorganic compound other than oxygen serves as the ultimate hydrogen acceptor. C₆H₁₂O₆ + SO₄^2- + H₂O--> H₂S + H₂O + CO₂ + 4-26 ATP

Release of the least amound of energy for transfer to a smallest number of ATP; usually an organic intermediate serves as the ultimate hydrogen acceptor.

C₆H₁₂O₆ --> acetaldehyde + H + CO₂ --> Ethanol + CO₂ + 2 ATP type of fermentation

C₆H₁₂O₆ --> pyruvic acid + H+ + CO₂ -->lactic acid + CO₂ + 2 ATP type of fermentation

Yeilds 36 ATP per glucose molecule; four series of reactions required.

The breakdown of glucose (6-c) to 2 molecules of pyruvate (PYR) (3-c); small amounds of ATP are generated. Engery using and energy producing. ("splitting sugars")

Cytoplasm is the site for this type of Aerobic Respiration.

a. Glucose (6-c) is phosphorylated in energy-requiring steps, then split to form two molecules of PYR (3-c). b. Enzymes remove protons(H+) and electrons (e-) from PYR to change NAD+ to NADH (which is used later in electron transport). c. By substrate-level phorphorylation, four ATP are produced.

Inputs: 1 Glucose, 2 ATP, 4 ADP, and 2 NAD+

Outputs: two PYR (3-c), 4 ATP, 2 ADP, and 2 NADH per glucose molecule degraded

Both of these have a Net energy gain: 2 ATP

Oxidation of PYR (3-c) to Acetyl-CoA (2-c); no ATP is generated.

Mitochondria is the site for this type of Aerobic Respiration.