Electron Transport Chain Cellular Respiration Part I: Glycolysis and the Krebs Cycle Krebs Cycle Glycolysis Electron Transport Chain

Remember! Cell respiration is an exergonic reaction Energy released is used to make ATP

Cellular respiration uses enzyme-catalyzed reactions to harvest energy from simple carbohydrates.

Add in to your notes: These can be catabolized into glucose for use in glycolysis: Carbohydrates (most common) Lipids (more energy than carbs) Proteins (starving  pull from muscles   )

The Three Steps of Cellular Respiration Krebs Cycle Glycolysis Electron Transport Chain

Summary: Glycolysis: the breakdown of one glucose molecule into two pyruvate. It occurs in the cytoplasm and is anaerobic.

Glycolysis: Summary Investment: Payoff: Glucose 2 ATP 2 NAD+ 2 Pyruvate 2 ATP (4 made, but 2 used) 2 NADH Oxidation Reaction

Glycolysis ends with pyruvate. Energy is stockpiled in pyruvate If oxygen is present, pyruvate enters mitochondria in eukaryotes (and stays in ctyosol of prokaryotes) The oxidation of glucose continues!

CoA makes it very reactive- has high potential energy! Pyruvate is transported from the cytoplasm to the mitochondrion, where it is converted to Acetyl CoA. CoA makes it very reactive- has high potential energy! Which functional group is removed?

Transition Reaction Summary: Investment: 2 Pyruvate Payoff: 2 Acetyl Coenzyme A 2 NADH 2 CO2 (waste product)

The Krebs Cycle (Also known as the Citric Acid Cycle or the TCA Cycle)

SUMMARY: The Krebs Cycle occurs in the matrix of the mitochondria.

SUMMARY: The Krebs Cycle produces 2 ATP through substrate-level phosphorylation. (1 glucose=2 pyruvate…so this happens 2x per glucose)

During the Krebs Cycle , coenzymes NAD+ and FADH each receive high energy electrons and become NADH and FADH2.

The Krebs Cycle Summary: Investment: 2 Acetyl CoA Payoff: 2 ATP 6 NADH 2 FADH2 4 CO2 (waste) Substrate-Level Phosphorylation

In glycolysis and the Krebs Cycle… ATP is made by substrate-level phosphorylation Enzyme directly transfers a phosphate group to ADP from a substrate In the ETC, it is made by oxidative phosphorylation (using a series of proteins)

Summary so far. Next…the ETC! Glycolysis Transition Reaction Krebs Cycle Investment: Glucose 2 ATP 2 NAD+ Investment: 2 Pyruvate Investment: 2 Acetyl CoA Payoff: 2 Pyruvate 2 ATP (4 made, 2 used) 2 NADH Payoff: 2 Acetyl Coenzyme A 2 NADH 2 CO2 (waste product) Payoff: 2 ATP 6 NADH 2 FADH2 4 CO2 (waste) Oxidation Reaction Substrate-Level Phosphorylation

REMEMBER! This is happening in multiple places within a cell at any given time This is happening in all cells at any given time