Lecture 30 - Respiration PDF

# Lecture+30+Respiration ## Redox Reactions Redox reactions transfer electrons from one molecule to the next. This provides the energy to drive ATP synthesis. * High energy state: Electrons are removed from glucose. * Low energy state: ATP is produced. * Redox reactions ## Oxidation and Redu...

# Lecture+30+Respiration ## Redox Reactions Redox reactions transfer electrons from one molecule to the next. This provides the energy to drive ATP synthesis. * High energy state: Electrons are removed from glucose. * Low energy state: ATP is produced. * Redox reactions ## Oxidation and Reduction Reactions **A. Oxidation** 1. Loss of electrons e- 2. Oxidized and lose energy **B. Reduction** 1. Gain of electrons e- 2. Reduced and gain energy **C. Redox reactions are coupled** 1. When something takes your electrons (oxidizes you), it gets reduced ## A Redox Reaction A gives its electron to B. * A is **oxidized** * B is **reduced**. * A is the **donor** * B is the **receptor** ## Good Way To Remember Redox: **LEO the lion says GER** * **LEO** *(Lose Electons = Oxidized)* * **GER** *(Gain Electrons = Reduced)* ## When You See H+ Getting Added or Removed, It Represents an Electron. * NAD+ is reduced to NADH * NAD+ + 2e+2H+→ NADH + H+ ## LEO Says GER and H+ Transfer * **LEO** *(Lose Electons = Oxidized)* * **GER** *(Gain Electrons = Reduced)* * **GER!** H+ transfer! ## Oxidation Of Something Releases Energy * CH4+2O2→CO2+Energy+2H2O ## Redox Reactions Transfer Electrons From One Molecule To The Next * Electrons move from **glucose** to **oxygen**. ## Cellular Respiration is the Oxidation of Glucose * High energy C-H bonds in glucose get converted into low energy C-O bonds in CO2. * Sugar is oxidized to CO2. * Oxidation: C6H12O6 + 602 → 6CO2 + 6H2O + energy * Reduction: O2 is reduced to water. ## Cellular Respiration 1. **Sugar Break Down** * **Glycolysis** * Cytosol 2. **Pyruvate Oxidation and Citric Acid Cycle** * Mitochondria 3 **Oxidative Phosphorylation** ## Cellular Respiration: Three Stages 1. Glycolysis 2. Pyruvate Oxidation and Citric Acid Cycle 3. Oxidative Phosphorylation ## Two Ways To Make ATP During Respiration 1. **Substrate-level phosphorylation** 2. **Oxidative phosphorylation** * Phosphorylation refers to adding a phosphate onto ADP to make ATP. ## Making ATP: Substrate-level Phosphorylation vs. Oxidative Phosphorylation **Substrate-level** * Phosphorylated donor molecule * Enzyme * Unphosphorylated product molecule **Oxidative** * ATP Synthase * ADP + P ## Why Is It Called Substrate-level Phosphorylation? Because an enzyme transfers a phosphate from it's substrate to ADP to produce ATP. ## Why Is It Called Oxidative Phosphorylation? * Oxidative phosphorylation makes ATP using ATP synthase and enzyme. * The "oxidative" part refers to the electron carriers NADH and FADH2 donating their electrons (i.e. getting oxidized) to power the ATP synthase. ## Reactions of Glycolysis * Glycolysis * Pyruvate oxidation * Citric acid cycle * Oxidative phosphorylation * Cytosol ## NADH and FADH2 NADH and FADH2 are the electron shuttles of cellular respiration. They are like delivery trucks transporting high-energy electrons to their destination, where their "cargo" powers the cellular ATP factory! ## Redox Reactions of The High Energy Electron Carriers NAD and FAD **Reduction of NAD+ and FAD** * NAD+ + 2e+2H+ → NADH + H+ * FAD+2e+2H+→FADH2 **Oxidation of NAD+ and FAD** * NADH → NAD+ + 2e- + H+ * FADH2 → FAD + 2e+2 H+ ## Glycolysis **A. Universal metabolic process** **B. Occurs in cytosol** **C. Glucose (6 carbons) is oxidized into two molecules of pyruvate (3 carbons each).** **D. Energy generated as ATP and NADH** **E. Does not require O2, it is anaerobic** ## ATP is Invested To Make Glucose More Energetic * Invest a little ATP to get a lot later (and some NADH too). * The image shows two possible pathways that glucose can take. ## Investment and Payoff in Glycolysis * **Energy Investment:** ATP+ADP+Pi * **Energy Recovery**: 2 NAD, 2 NADH + H+, 2 ADP+2 Pi, * **2 Pyruvate** By end of Glycolysis the 2 ATP investment is recouped and 2 more ATP are obtained along with 2 molecules of NADH and 2 Pyruvate ## Summary: Glycolysis * 1 glucose → 2 pyruvate + 2 H₂O * 4 ATP generated - 2 ATP used → 2 ATP * 2 NAD+ + 4 + 4 H+ → 2 NADH + 2 H+