EXAM 3 NOTES: Cell Biology

Energy Sources for Cells

Cells require a consistent input of energy, which can come from the sun or from chemical energy sources like sugars and fats.

ATP and Activated Carrier Molecules

Energy released by metabolism is captured and stored in activated carrier molecules such as ATP, NADH/NADPH, and FADH2.

Gibbs Free Energy (G)

The energy used by a cell to drive a chemical reaction is known as Gibbs free energy (G), where a negative ∆G indicates a spontaneous reaction.

Glucose Metabolism

Glucose is a key component in generating ATP to meet cell energy demands through processes like glycolysis and the Krebs cycle.

ATP Synthesis Mechanisms

Cells can synthesize ATP through three mechanisms:phosphorylation using sunlight, oxidative phosphorylation using activated carriers, and substrate-level phosphorylation through enzyme-catalyzed reactions.

Glycolysis

Glycolysis is a metabolic pathway that breaks down glucose into pyruvates, occurring in the cytosol and producing ATP, NADH, and NADH.

Fermentation

In the absence of oxygen, pyruvate can be converted into lactic acid or ethanol through fermentation, a process important for energy production in muscles and in the production of bread and alcohol.