1 / 18

Cellular Respiration

Cellular Respiration. Principles of Energy Harvest. Ultimately, the NRG in an ecosystem begins as sunlight and leaves as heat Chemical elements are recycled Photosynthesis and Respiration are essential processes that allow NRG to flow through an ecosystem. NRG from food.

andie
Download Presentation

Cellular Respiration

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. Cellular Respiration

  2. Principles of Energy Harvest • Ultimately, the NRG in an ecosystem begins as sunlight and leaves as heat • Chemical elements are recycled • Photosynthesis and Respiration are essential processes that allow NRG to flow through an ecosystem

  3. NRG from food • Catabolic pathways produce ATP from organic compounds • Fermentation • Partially degrades sugars • Occurs when no O2 present • Cellular Respiration • C6H12O6 + 6O2 6CO2 + 6H2O + E (ATP + heat)

  4. Redox reactions • In order to make ATP, electrons must be rearranged • Oxidation/Reduction • LEO the lion says GER • Lose Electrons = Oxidation • Gain Electrons = Reduction • Reducing agent: e- donor • Oxidizing agent: e- acceptor

  5. Oxidizing agent in Respiration • NAD+ (nicotinamide adenine dinucleotide) • Removes electrons from food (series of reactions) • NAD+ is reduced to NADH • Enzyme action: dehydrogenase (removes 2 e- and 2 H+) • NRG in NADH is used to make ATP (controlled production of NRG)

  6. Electron Transport Chains • Electron carrier molecules (membrane proteins) • Shuttle e- that release NRG used to make ATP • Sequence of reactions that prevents NRG release in one explosive step • Electron route: food NADH  ETC O2 • Oxygen is the final e- acceptor

  7. Cellular respiration • Glycolysis: • cytosol • degrades glucose into pyruvate • Citric Acid (Kreb’s) Cycle: • mitochondrial matrix • pyruvate into CO2 • Electron Transport Chain: • inner membrane of mitochondrion • electrons passed to oxygen • NRG trapped to make ATP

  8. Glycolysis • 1 Glucose ---> 2 pyruvate molecules • Energy investment phase: cell uses 2 ATP to phosphorylate fuel • Energy payoff phase: 4 ATP produced by substrate-level phosphorylation and NAD+ is reduced to NADH by food oxidation • Net NRG yield per glucose: 2 ATP, 2 NADH

  9. Kreb’s Cycle • If molecular O2 is present… • Each pyruvate (2 from glycolysis) converted into acetyl CoA • CO2 released • NAD+ ---> NADH • coenzyme A (from B vitamin) attached; makes molecule very reactive • In each turn, 2 C atoms enter (pyruvate) and 2 exit (CO2) • For each pyruvate: • 3 NAD+ reduced to NADH • 1 FAD+ reduced to FADH2 • 1 ATP molecule

  10. Electron Transport Chain • e- carriers, NADH and FADH2 donate e- to the chain • e- passed “downhill” to more electronegative molecules as they move on • Most carrier molecules are cytochromes • have a heme group that accepts and donates e-

  11. Chemiosmosis • Electron Transport chain sets up a H+ concentration gradient • e- flow is exergonic; released NRG is used to pump protons across the membrane • “proton-motive force” • As H+ diffuses back in, ATP synthase makes ATP • Chemiosmosis: energy coupling mechanism • NRG of H+ gradient drives cellular work

  12. ATP Production • ATP synthase: • produces ATP using the H+ gradient • harnesses flow of H+ back into matrix • phosphorylates ADP to ATP (oxidative phosphorylation) • Produces 32-34 molecules of ATP

  13. Review: Cellular Respiration • Glycolysis: • 2 ATP (substrate-level phosphorylation) • Kreb’s Cycle: • 2 ATP (substrate-level phosphorylation) • Electron transport & oxidative phosphorylation: • 2 NADH (glycolysis) = 6 ATP • 2 NADH (acetyl CoA) = 6 ATP • 6 NADH (Kreb’s) = 18 ATP • 2 FADH2 (Kreb’s) = 4 ATP 38 TOTAL ATP/glucose

  14. Fermentation • Occurs when no O2 is present • Produces some ATP and replenishes NAD+ • Keeps glycolysis going so some ATP can be produced • Facultative anaerobes (yeast/bacteria) can survive off of fermentation alone

  15. Types of fermentation • Alcoholic • pyruvate to ethanol • Bacteria, yeast, most plants • Production of bread and alcoholic beverages • Lactic acid • pyruvate to lactate • Fungi, bacteria, human muscle cells • Production of cheese and yogurt • Causes muscle fatigue and pain during strenuous exercise

  16. Other Metabolic Pathways • Proteins • broken down into amino acids • Converted into intermediates used in glycolysis and Kreb’s • Lipids • Broken down into glycerol and fatty acids • Glycerol transformed into an intermediate in glycolysis • Fatty acids broken down by beta-oxidation and transformed into Acetyl Co-A

More Related