BIO 41,Ch6

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BIO 41,Ch6
2013-04-22 16:45:49
Cellular Respiration Bio 41

Cellular Respiration
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  1. Photosynthesis
    Uses light energy form sun to power a chemical process that builds organic molecules
  2. Chemical ingredients in Photosynthesis
    Carbon Dioxide (CO2) + Water (H2O) = Glucose (C6H12O6)
  3. Cellular Respiration
    • Chem process that harvests energy that's stored in sugars & other organic molecules
    • Uses Oxygen Gas (O2) to help convert energy extracted from organic fuel to another source of chem energy called **ATP
  4. Mitochondria
    • Where production of ATP during cellular respiration occurs mainly in these organelles
    • In both plants & animals
  5. What are the waste products of cellular respiration?
    • CO2 & H2O
    • SAME ingrediants used for **Photosynthesis
  6. Animals perform cellular respiration, but not photosynthesis. What performs both?
  7. Aerobic process
    • Process requiring Oxygen
    • **Ex: Cellular Respiration
  8. Equation for Glucose durig Cellular Respiration
    • C6H12O6 + 6 O2 >>> 6 CO2 + 6 H2O + ATP
  9. Cellular Respiration: Main Function
    Generates ATP for cellular work
  10. Process of Cellular Respiration can produce up to how many ATP molecules for each glucose molecule consumed?
  11. Redox (Oxidation-reduction) reactions
    Chem reactions that transfer electrons from one substance to another
  12. Oxidation
    Loss of electrons during redox reaction
  13. Reduction
    Acceptance of electrons during redox
  14. ADDING electrons is called REDUCTION
    Neg charged electrons added to an atom REDUCE amount of pos charge of that atom
  15. Oxygen is reduced during cellular respiration, accepting electrons (& hydrogen) lost from glucose:
  16. Simple Redox Reaction
    • All-at-once reaction, like reaction of hydrogen & oxygen to form water
    • Reaction releases large amout of energy as electrons of hydrogen "fall" into their new bonds w/ oxygen.
    • Difficult for cell to capture such burst of energy & put to useful work.

  17. Role of Oxygen in Harvesting Food Energy
    • In cellular respiration, elecrons "fall" in small steps from food to oxygen, producing water. (Also more CONTROLLED "fall" of electrons) NADH transfers electrons from food to an electron transport chain. Oxygen "pulls" electrons down chain
    • ***Water isn't only thing produced when hydrogen & its bonding electrons change partners from glucose to oxygen; ENERGY is released too!
  18. Why does electron transfer to oxygen release energy?
    • In redox reactions, oxygen is "electron grabber". **Oxygen atom attracts electrons more strongly than almost any other type of atom
    • When electrons move from glucose to oxygen, its as tho they're falling.
    • However, potential energy is unlocked; its attraction of electrons to oxygen that causes "fall" & energy release during cellular respiration
  19. NADH (Molecule)
    • ---Transfer of electrons from organic fuel (food) to NAD+ reduces NAD+ to NADH (H represents transfer of hydrogen along w/ electrons)
    • ELECTRON CARRIER involved in cellular respiration & photosynthesis
    • Carries electrons from glucose & other fuel molecules & deposits them at top of electron transport chain
    • Generated during glycolysis & cytric acid cycle
  20. Electron transport chain
    • Series of electron carrier molecules that shuttle electrons during redox reactions that release energy used to make ATP
    • Each member of chain first accepts & then donates electrons
    • ----Located in:
    • INNER MEMBRANE of Mitochondria
    • Thylakoid membrane of chloroplasts
    • Plasma Membrane of Prokaryotes
  21. Each link in an electron transport chain is actually a what?
    Molecule, usually a protein
  22. During a redox reaction, the addition of electrons is called ______, while removal of electrons is caled ______.
    Reduction; Oxidation
  23. At both organismal & cellular levels, respiration involves taking in gas _____ & expelling the gas ______.
    O2; CO2
  24. What chemical ingredients do plants require from environment in order to synthesie their own food?
    CO2, H2O, & soil minerals
  25. The first molecule from Electron Transport Chain (ETC):
    • Accepts electrons from NADH.
    • Thus NADH carries electrons from glucose & other fuel molecules & deposits them at top of the ETC
    • Electrons cascade down chain, from molecule to molecule, like electron bucket brigade
    • Finally, molecule at bottom of chain "drops" electrons to oxygen, which picks up hydrogen FORMING WATER
  26. Road Map of Cellular Respiration
    • A metabolic pathway=Not a single chemical reaction, but a SERIES of reactions (more than 2 dozen); a specific enzyme catalyzes each reaction
  27. 3 Main Metabolic Stages of Cellular Respiraton:
    • Glycolysis
    • Citric Acid Cycle
    • Electron Transport
  28. 3 Main Metabolic Stages of Cellular Respiraton: 1.)Glycolysis
    • Means "splitting of sugar"
    • **Enzymes are in Cytoplasm
    • --- FIRST: 6-Carbon glucose molecule splits into two 3-Carbon molecules. Each glucose from split needs ATP molecule
    • --- NEXT: 3-Carbon molecules donate high-energy electrons to NAD+ forming NADH
    • --- THEN: In addition to NADH, glycolysis also makes 4 ATP molecules directly when enzymes transfer phosphate groups from fuel molecules to ADP, PRODUCING net of 2 molecules of ATP per Glucose
    • ---RESULT: 2 molecules of Pyruvic Acid which still holds most energy of Glucose
  29. Conversion of Pyruvic Acid ==> Acetyl CoA

    • --- FIRST: Pyruvid Acid loses carbon as CO2. This is first of waste product shown in breakdown of Glucose. Remaining fuel molecules, each w/ only 2 carbons left, are Acetic Acid (in Vinegar)
    • --- THEN: Oxidation of fuel generates NADH
    • --- FINALLY: Acetic Acid is attached to molecule Coenyme A (CoA) to form acetyl CoA. That escorts acetic acid into first reaction of cycle, stripping & recycling it
    • ***This Process Occurs TWICE
  30. 3 Main Metabolic Stages of Cellular Respiraton: 2.)Citric Acid Cycle (Kreb's Cycle)
    • **Enzymes are dissolved in fluid w/in mitochondria
    • --- FIRST: Acetic acid joins 4-Carbon acceptor molecule to form 6-Carbon product Citric Acid.
    • --- SECOND: For every acetic acid molecule that enters cycle as fuel, 2 CO2 molecules eventually exit as waste product, Making cycle harvest ENERGY from FUEL in the process
    • --- THIRD: Some energy is used to produce ATP directly, but cycle captures much more energy in form of ~NADH & FADH2~
    • --- FINALLY: All carbon atoms that entered as fuel are accounted for as CO2 exhaust, & 4-Carbon acceptor molecule is recycled.
    • ***Completes breakdown of glucose all the way to CO2 (One of waste products of Cell Respir) ALSO TURNS TWICE
  31. Glycolysis & Citric Acid Cycle (Kreb's Cycle) generate a small amount of ATP directly, but they generate much more ATP indirectly, via redox reaction that transfer electrons from fuel molecules to what?
    To NAD+, forming NADH
  32. 3 Main Metabolic Stages of Cellular Respiraton: 3.)Electron Transport
    • ETC functions as chem machine that uses energy released by "fall" of electrons to pump Hydrogen ions (H+); Also proteins & other molecules that make up ETCs are embedded w/in inner membrane of mitochondria
    • This pumping causes ions to be more concentrated on one side than other, then storing potential energy
    • Electron transport from NADH to oxygen releases=ENERGY ur cells use to make most of their ATP
  33. How the energy previously stored in NADH & FADH2 can be used to generate ATP:
    • --- NADH & FADH2 transfer electrons to ETC
    • --- ETC used this energy supply to pump H+ across inner mitochondrial membrane
    • --- Oxygen pulls electrons down transport chain
    • --- H+ concentrated on 1 side of membrane rushes back "downhill" thru ATP synthase; this action spins component of ATP synthase (Turbines of DAM)
    • --- Rotation activates parts of synthase molecule that attach phosphate groups to ADP molecules to generate ATP
  34. ATP synthesis by Direct Phosphate Transfer
    • Glycolysis generates ATP when enzymes transfer phosphate groups directly from fuel molecules to ADP
  35. What stages of Cell Respir. take place in Mitochondria?
    Citric Acid Cycle & Electron Transport
  36. 2 molecules of what compound are produced by glycolysis?
    Pyruvic Acid
  37. 2 molecules of what compound actually enter Citric Acid Cycle?
    Acetic Acid
  38. ATP synthase
    • -- Protein cluster, found in cellular membrane that uses energy of hydrogen ion concentration gradient to make ATP from ADP
    • -- Provides port thru which hydrogen ions (H+) diffuse
    • **ALSO FOUND IN:
    • Inner membrane of mitochondria
    • Thylakoid membrane of chloroplasts
    • Plasma membrane of prokaryotes
  39. Poison Cyanide in ETC:
    • Produces its deadly effect by binding to 1 of protein complexes
    • When bound there, cyanide blocks passage of electrons to oxygen
    • Result: No H+ gradient is generated; No ATP made; Cell Stops; Organisms die
  40. ______ was the lethal agent in the infamous case of product tampering: The Tylenol murders of 1982 where 7 died in Chicago after ingesting Tylenol capsules laced w/ _______. Perpetrator was never caught
  41. If left untreated, a glucose imbalance can lead to what?
    Cardiovascular diseas, coma, & even death
    • Some Metabolic routes for use of Carbs, Fats, & Proteins= Fuel for Cell Respir.
    • **Respiration is versatile metabolic furnace that can "burn" many other kind of food molecules.
  43. Which stage of Cell Respir. ration produces majority of ATP?
    Electrron Transport
  44. Overall Functioning of Cell Respir.:
    Generating up to 38 molecules of ATP per molecule of glucose (Actual # can very by a few)
  45. How many molecules of ATP can be produced from 1 molecule of glucose during Fermentation?
  46. Summary of ATP yield during Cell Respir.
    • ---Helps u add up ATP molecules
    • GLYCOLYSIS & CITRIC ACID CYCLE each contribute 2 ATP by Direct Synthesis
    • The rest of ATP molecules are produced by ATP Synthase Machines, powered by "fall" of electrons from food ==> Oxygen
    • Electrons are carried from organic fuel to ETCs by NADH & FADH2.
    • *Each electron pair "dropped" down transport chain from NADH can power synthesis of up to 3 ATP.
    • *Each pair transferred too an ETC from FADH2 is worth up to 2 ATP
  47. Anaerobic
    Cells working "w/out oxygen"
  48. Fermentation (IN HUMAN MUSCLE CELLS)
    • Anaerobic harvest of food energy by some cells
    • --Relies on Glycolyis= which produces 2 ATP molecules for each glucose molecule broken down to Pyruvic Acid
    • --Cells must consume more glucose fuel per second
    • --Regenerates NAD+ when NADH drops electron cargo down ETCs to O2, HOWEVER, recycling of NAD+ cn't happen cuz NO O2 to accept electrons
    • --INSTEAD, NADH disposes electrons by adding to Pyruvic Acid from Glycolysis
  49. Fermentation: Producing Lactic Acid
    • Glycolysis produces ATP even w/out O2, requiring continuous NAD+ supply to accept electrons from glucose
    • NAD+ is regenerated when NADH transfers electrons it removed from food to Pyruvic Acid, thereby producing Lactic Acid (or other waste products, depending on species of organism)
    • Lactic Acid by-product eventually transported to LIVER, where LIVER CELLS convert it back to Pyruvic Acid
  50. What kind of acid builds up in human muscle during strenuous activity?
    Lactic Acid
  51. Exercise physiologists (biologists who study effects of exercise on body) have long speculated about role that ________ Acid plays in muscle fatigue
    Lactic Acid
  52. Who is A.V. Hill & what did he do?
    • A British biologist; One of the founders of the field of Exercise Physiology & understood Muscle Contraction
    • --Observed that muscles produce Lactic Acid under anaerobic conditions, WONDERING if Lactic Acid causes muscle fatigue
    • --Tested Frog Muscles towards CONCLUSION: "Lactic Acid accumulation is primary cause of FAILURE"
    • ***HOWEVER, when it comes to Human Temp, certain individuals who are unable to accumulate Lactic Acid have muscles that fatigue MORE rapidly. Still, the role of lactic acid is not completely figured & still continues to change
  53. Fermentation in Microorganisms
    • Muscles can't function by Lactic Acid Fermentation for too long, but 2 ATP molecules produced per glucose molecule during Ferm is enough to sustain many microorganisms
    • Such microbes transform MILK=>CHEESE, SOUR CREAM, YOGURT (Sharp/Sour flavors from Lactic Acid)
    • Food Industry used Fermentation to produce SOY SAUCE=>SOYBEANS, PICKLE CUCUMBERS, OLIVES, CABBAGE
  54. Yeast, a microscopic fungus, is capable of both Cellular Respiration & what?
  55. Fermentation: Producing Ethyl Alcohol
    • -- If yeast cells are kept in anaerobic environment, they are forced to ferment sugars & other foods to stay alive==PRODUCING Ethyl Alcohol as WASTE PRODUCT instead of Lactid Acid.
    • -- This Alcoholic Ferm. also releases CO2.
    • (Beer, Wine)
    • -- The CO2 bubbles from this Ferm. causes bread dough to rise
  56. The oldest known fossils of bacteria date back more than __________, but significant levels of O2 did not accumulate in the atmostphere until about ___________
    3.5 billion yrs; 2.7 billion yrs ago
  57. For almost a billion yrs, Prokaryotes must have generated ATP exclusively from what?
    Glycolysis <===Occurs in ALMOST ALL Organisms