Cellular Respiration Chapter 9

What you need to know! The role of glycolysis in oxidizing glucose to two molecules of pyruvate. The process that brings pyruvate from the cytosol into the mitochondria and introduces it into the citric acid cycle. How the process of chemiosmosis utilizes the electrons from NADH and FADH2 to produce ATP.

Aerobic Cellular Respiration Definition: harvesting chemical bond energy (covalent) stored in glucose molecules Redox reaction that: Reduces O2 to H2O Oxidizes glucose to CO2 Animal and plant cells Location: cytosol and mitochondria e- taxis of cytoplasm and matrix are NAD, FAD Rx: 6O2 + C6H12O6  6 CO2 + 6 H20 + 38 ATP

3 Stages Glycolysis Krebs Cycle (Citric Acid Cycle) Oxidative Phosphorylation (ETC) In the presence of O2 most ATP are made via chemiosmosis gradients in the ETC Some ATP are made through substrate level phosphorylation Rx: ADP + P  ATP

Anatomy of a Mitochondrion

The Big Picture

1. Glycolysis Location: cytoplasm Breaking down glucose (C6) into 2 pyruvic acids (C3) Needs 2 ATP as activation energy Subsequent enzyme Rx’s produce 4 ATP via substrate level phosphorylation Glucose (C6) is converted into 2 pyruvic acids (C3) with a net yield of 2ATP & 2 NADH No O2 is needed

Preparatory Step in Mitochondria (directly before Krebs) Both Pyruvic acids are turned into Acetyl CoA (C2) by: The attachment of CoA, releases one carbon as CO2 Formation of 2 NADH

2. Krebs Cycle (Citric Acid Cycle) Location: mitochondria Complete oxidation of Acetyl Each cycle: Removal of CoA from 1 Acetyl Releasing 2 carbons as CO2 Production of 1 ATP via substrate level phosphorylation Production of 3 NADH Production of 1 FADH2

3. Oxidative Phosphorylation Location: inner membrane of mitochondria Oxygen needed 2 phases: Electron Transport Chain: rows of interconnected membrane bound proteins Creation of H+ gradient Final electron acceptor of aerobic cellular respiration is Oxygen Chemiosmosis: ATP Synthase makes ATP Uses H+ gradient

Electron Transport Chain NADH and FADH2 deposit high energy electrons to the chain NADH feeds e- in the ETC at a higher point than FADH2 thus e- from NADH pump more H+ which in turn produce more ATP The e- moves down the chain of proteins Energy from the e- is used to power the ETC which pumps H+ into the intermembrane space e- are sucked out of the chain by Oxygen: O + 2e- + 2H+  H2O

Chemiosmosis H+ are allowed back into the matrix by ATP Synthase This electrical flow provides the energy necessary to bind P to ADP ADP + P  ATP

Oxidative Phosphorylation

ATP Yield Glycolysis = 4 Kreb = 2 ETC = 34 Activiation Energy = -2 Total = 38 ATP

Cellular Suffocation Clogging of ETC due to absence of O2 = no ATP e- have nowhere to go Glycolysis and Krebs Cycle stop Cyanide and carbon monoxide are poisonous gases because they clog the ETC

The Big Picture