The Krebs Cycle & Electron Transport

Chapter 9.2

Krebs Cycle (aka Citric Acid Cycle)

• Aerobic part of cellular respiration, it requires oxygen

• The process of breaking pyruvic acid into carbon dioxide (CO2) using oxygen (O2)

• This process releases energy

• Takes place in mitochondrion• Pyruvic acid (3C) from

glycolysis is broken down to CO2 (leaves 2C) & electrons are removed to change NAD+ to NADH

• Acetyl-CoA (2C) + 4 C = citric acid (6C)

• Citric acid (6 C) is broken down to 5C and then to 4C (CO2 & NADH formed each time)

• 1 ATP & 1 FADH2 are also formed

• 4 NADH formed

Electron Transport Chain• ETC uses the high energy

electrons from the Krebs Cycle to convert ADP into ATP

• ETC composed of carrier proteins in the inner membrane of the mitochondrion

• At the end of ETC is an enzyme that combines e- from the ETC with H & O to form water

• Oxygen serves as final e- acceptor of the ETC

•2 e- moving down the ETC transports H+ across the membrane; charge differential is created and used to form ATP

•Most of the ATP produced during cellular respiration is made during the Electron Transport Chain

Glycolysis = 2 ATP Krebs cycle = 2 ATP electron transport = 32 ATPTotal 36 ATP

Totals

• Video: http://www.copernicusproject.ucr.edu/ssi/HSBiologyResources.htm

Glycolysis and Cellular Respiration