1 / 41

Chapter 9

Chapter 9. Cellular Respiration. I CAN ’ S/ YOU MUST KNOW. The difference between fermentation & cellular respiration The role of glycolysis in oxidizing glucose to two molecules of pyruvate

bvoyles
Download Presentation

Chapter 9

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Chapter 9 Cellular Respiration

  2. I CAN’S/YOU MUST KNOW • The difference between fermentation & cellular respiration • The role of glycolysis in oxidizing glucose to two molecules of pyruvate • The process that brings pyruvate from the cytosol into the mitochondria & introduces it into the citric acid cycle • How the process of chemiosmosis utilizes the electrons from NADH & FADH2 to produce ATP

  3. 9.1 • Catabolic pathways release energy by oxidizing organic fuels • Occur when molecules are broken down • Releases the molecules’ energy

  4. 2 types of catabolism • 1) Fermentation • Partial degradation of sugars that occurs without O2 • 2) Cellular Respiration • Most prevalent & efficient catabolic pathway • Uses O2 as a reactant with the organic fuel • Known as AEROBIC RESPIRATION • CAN also use anaerobic respiration

  5. Carbs, Fats, & Proteins are all broken down in cellular respiration • Glucose is the primary nutrient molecule used: • C6H12O6 + 6O6 6CO2 + 6H2O + ENERGY (ATP/heat)

  6. The exergonic release of energy from glucose is used to phosphorylate ADP to ATP • Life processes constantly consume ATP • Cellular respiration burns the organic fuels & uses the energy to regenerate ATP

  7. Redox Reactions • Electrons are transferred from one reactant to another • Reduction = substance gains electrons & energy (reduced + charge) • Oxidation = substance loses electrons & energy (oxidized) • LEO GER

  8. The electron donor is called the reducing agent • The electron receptor is called the oxidizing agent • Some redox reactions do not transfer electrons but change the electron sharing in covalent bonds

  9. During cellular respiration, the fuel (such as glucose) is oxidized, and O2 is reduced:

  10. At key steps in cellular respiration: • Electrons are stripped from glucose • Each electron travels with a proton (forms hydrogen) • The hydrogen atoms are not transferred directly to oxygen (formula shows that) – they are passed to an electron carrier

  11. Electron Carrier: • Coenzyme NAD+ • NAD+ accepts 2 electrons + the stabilizing hydrogen ion to form NADPH • NADPH has been reduced & has gained energy • Stored energy used later to make ATP

  12. More than: C6H12O6 + 6O6 6CO2 + 6H2O + ENERGY • Cellular respiration has three stages: • Glycolysis (breaks down glucose into two molecules of pyruvate) • The citric acid cycle (completes the breakdown of glucose) • Oxidative phosphorylation (accounts for most of the ATP synthesis)

  13. 9.2Glycolysis • Occurs in cytosol • The degradation of glucose begins as it is broken down into two PYRUVATE molecules • The 6-Carbon glucose molecule is split into TWO 3-Carbon sugars through a long series of steps

  14. 2 major phases: • Energy (ATP) consuming phase • Energy (ATP) producing phase

  15. Energy consuming • 2 ATP are used • Destabilize glucose & makes it more reactive • Energy producing • Later in glycolysis, 4 ATP are made • Results in net gain of 2 ATP • 2 NADH are also made – used later

  16. NET gain of 2 ATP & 2 NADH • Most potential energy is still in the 2 pyruvates • Pyruvates will then move to step 2 – citric acid cycle

  17. 9.3Kreb’s (Citric Acid) Cycle • When O2 is present, pyruvates enter the mitochondria • Before Kreb’s begins, pyruvate is converted to acetly CoA

  18. 1) Pyruvate uses a transport protein to move into the matrix of the mitochondria • 2) When there, an enzyme complex removes a CO2, strips away electrons to convert NAD+ to NADH, & adds coenzyme A to form acetyl CoA • 3) Two acetyl CoA’s are produced per glucose. It now enters the citric acid cycle

  19. Kreb’s (Citric Acid) • 8 steps – each catalyzed by a specific enzyme • The job of breaking down glucose is completed with CO2 released as waste • Each turn of the cycle requires the input of one acetyl CoA • Must make 2 turns before the glucose is completely oxidized

  20. One turn produces: • 2CO2, 3NADH, 1FADH2 & 1 ATP • Thus 2 turns produce: • 4CO2, 6NADH, 2FADH2 & 2 ATP

  21. At the end of the Kreb’s cycle all 6 carbons from glucose have been released as CO2 • Only 2 ATP have been produced • The rest is held in the electrons in the NADH & FADH2 • Utilized in the Electron Transport Chain

  22. 9.4ETC • The electron carriers will donate electrons to power ATP synthesis through OXIDATIVE PHOSPHORYLATION • In the cristae of the mitochondria • The ETC itself produces no ATP (comes from the products of the ETC)

  23. 4 Step Process of ETC • 1) ETC is embedded in the inner membrane of the mitochondria • Has 3 transmembrane proteins that act as hydrogen pumps • 2 carrier molecules that move electrons between hydrogen pumps

  24. 2) ETC is powered by electrons from NADH & FADH2 • As electrons flow, the loss of energy is used to pump protons across the inner membrane • At the end of the ETC, the electrons combine with 2 hydrogen ions & Oxygen to form water • Oxygen is the final electron acceptor – if none is available, the ETC STOPS!!!

  25. 3) Hydrogen ions flow down their gradient through ATP synthase (channel in protein) • ATP synthase harnesses proton motive force (the gradient of protons) to phosphorylate ADP • The proton motive force exists because inner mit. Membrane is impermeable to hydrogen ions

  26. 4) The movement of the proton motive force is called chemiosmosis • Energy-coupling mechanism that uses energy from the proton gradient to drive cellular work • The ETC & chemiosmosis compose OXIDATIVE PHOSPHORYLATION

  27. ATP yield per molecule of glucose is between 36 & 38 ATP • 32-34 comes from oxidative phosphorylation

  28. 9.5 • Fermentation allows a cell to produce ATP without Oxygen (anaerobic) • Consists of glycolysis (2 net ATP) & reactions that regenerate NAD+ • Oxygen not required to accept electrons

  29. Types of fermentation • 1) Alcohol • Pyruvate is converted to ethanol • Releases CO2 & oxidizing NADH to create more NAD+ • 2) Lactic acid • Pyruvate is reduced by NADH (NAD+) formed • Lactate is a waste product

  30. Facultative anaerobes • Organisms that make ATP by aerobic respiration if oxygen present • Can switch to fermentation in anaerobic conditions

  31. 9.6 • Proteins & fats are used to generate ATP through cellular respiration • Organic molecules are used in biosynthesis (the building of macromolecules) • Amino acids from the hydrolysis of proteins can be incorporated into the consumer’s own proteins

More Related