The reason we need to breathe! Cellular Respiration The reason we need to breathe!

A Video of the Process… https://www.youtube.com/watch?v=-Gb2EzF_XqA

What you need to know: Step 1: Glycolysis – splitting glucose into 2 pyruvate Step 2: Krebs Cycle (a.k.a. – Citric Acid Cycle) – pyruvic acid is broken down into carbon dioxide through a series of reactions Step 3: Electron Transport Chain – High energy electrons from Krebs Cycle are used to convert ADP to ATP

The particulars… Glycolysis (already covered previously) Krebs Cycle/Citric Acid Cycle As pyruvic acid goes through the Krebs Cycle, some of its carbons are released as Carbon Dioxide (CO2) Other carbons are changed to Acetyl-CoA, Citric Acid, and other compounds This process transfers high energy electrons to electron carriers NAD+ and FAD

The particulars… Electron Transport Chain High energy electrons from NADH and FADH2 to carrier proteins in the inner membrane of the mitochondria At the end of the ETC, an enzyme passes the electrons to the “final electron acceptor” = OXYGEN. Hydrogen ions join to make water (H2O).

The particulars… 36 ATP molecules are produced from each glucose! Electron Transport Chain (continued) Energy from the electrons pumps protons (H+) across the membrane from the matrix to the intermembrane space As H+ moves back into the matrix, it causes ATP synthase to turn, generating ATP from ADP by attaching a phosphate (“phosphorylation”) 36 ATP molecules are produced from each glucose!

Energy and Exercise Quick Energy Response to danger or a sudden burst of speed by an athlete Small amount of existing ATP is used up fast Lactic acid fermentation makes more ATP Runners breathe hard after running because of their oxygen “debt” which must be paid to rid their muscles of lactic acid

Energy and Exercise Long-Term Energy Extended exercise requires more oxygen Cellular respiration makes lots of ATP but is slower than fermentation The body breaks down glycogen (a storage form of carbohydrate) first, then after about 20 minutes of exercise it begins to break down fats This is why aerobic exercise is good for maintaining a healthy weight.