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Chapter 9: Cellular Respiration and Fermentation.

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Presentation on theme: "Chapter 9: Cellular Respiration and Fermentation."— Presentation transcript:

1 Chapter 9: Cellular Respiration and Fermentation

2 Essential Knowledge  2.a.1 – All living systems require constant input of free energy ( ).  2.a.2 – Organisms capture and store free energy for use in biological processes ( ).

3 Cellular Respiration - Preview  Def - The process of releasing energy/ATP from food  Food - Stored energy in chemical bonds (provides fuel)  ATP - Useable energy for cellular processes  Wastes – CO 2 and H 2 O  Mitochondrion store most of equipment needed for rxn

4 Respiration (Rs) - Equation C 6 H 12 O O 2 6 CO H 2 O + energy (ATP or heat)  Rxn is spontaneous (- ∆ G)  The energy is released (exergonic) from the bonds in the org molecules Remember: Org molecules store energy in their arrangement of atoms Org molecules can be carbs, proteins or fats/lipids

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6 Focus of Chapter Cellular Rs 1. Purpose - what is the reaction suppose to do for the cell? 2. Location - where does it occur? 3. Requirements - what is needed to make it run? 4. Products - what does it produce? Other Fermentation, Redox

7 Fuel? What is used?  Organic molecules with a large amt of hydrogen make great fuel! Why? H becomes oxidized (only has one e-) very easily and energy is released Remember: Carbs, fats, proteins are storage bins for e- associated with hydrogen

8 Oxidation - definitions  Loss of electrons  Loss of energy  Loss of hydrogens from carbons  Ex: Na+ (of NaCl)

9 Food and Oxidation  Food (organic molecules) contain a lot of H atoms These serve as great long-term fuels Why? ○ Because H becomes easily oxidized (releases energy frequently)

10 Reduction - definitions  Gain of electrons (REDUCING + charge)  Gain of energy  Gain of hydrogens to carbons  Ex: O is often reduced! Why? Because electrons are pulled closer to O

11 Redox reactions

12 Equation for Rs C 6 H 12 O O 2 6 CO H 2 O + energy (ATP/heat) General Redox Equation: Xe- + Y  X + Ye- Reduced Oxidized

13 Redox reactions  Involves transfer of e- and energy release Sometimes doesn’t involve complete transfer  Red and Oxd reactions are usually paired or linked together. Why?Because e- transfer requires donor and acceptor  Many of the reactions will be done by phosphorylation  Redox video Redox video

14 Phosphorylation  Adding a phosphate group to a molecule Ex: ATP cycle (add P to ADP = ATP)  Two types: Oxidative AND substrate-level  The phosphate group adds “energy” to the molecule for chemical reactions (think ATP cycle) Endergonic rxn

15 Phosphorylation

16 Cell Respiration – 3 parts 1. Glycolysis 2. Krebs Cycle 3. Electron Transport Chain **Use page 167 as a starting point: Cellular Respiration - A Preview

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18 Glycolysis  Glyco- glucose -lysis: to split  Formula for glucose: C 6 H 12 O 6  Universal step in all Rs types.  Likely the earliest type of cell energy processes  Overview: Glucose splits into 2 3-C sugars (then oxidizes to form pyruvate)

19 Glycolysis  Function - To split glucose and produce NADH and ATP ATP made by substrate-level phosphorylation ○ Enzyme transfers phosphate group from substrate/reactant to ADP to make ATP  Location – Cytoplasm of the cell

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21 Electron Carrier Compounds  Molecules that transport or shuttle electrons within the cell  Exist in two forms: Oxidized (ox) Reduced (red)  Ex: NAD and FAD

22 NAD  Nicotinamide Adenine Dinucleotide  NAD e - NADH  NAD + = oxidized form  NADH = reduced form* *Reduced by e- from food oxidation

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24 Glycolysis Requirements  Glucose  2 ATP  4 ADP  2 NAD +  Can occur with or without O 2

25 Glycolysis - Products  2 Pyruvic Acids (a 3-Carbon acid)  2 ADP, 4 ATP, 2 NADH  NET RESULT: 2 ATP per glucose 2 NADH 2 pyruvate H 2 O Notice: No CO 2 made during this step! Glycolysis Intro

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27 Krebs Cycle  Oxidizes fuel from pyruvate molecules Remember? Pyruvate formed during glycolysis  Also called: Citric Acid Cycle Tricarboxylic Acid Cycle

28 Krebs Cycle  Function: Oxidize pyruvic acid (to make CO 2 )  Produces: NADH and FADH 2  Location: Mitochondria matrix  Before Krebs: Acetyl CoA must be formed Acetyl CoA is needed to actually start Krebs

29 Pyruvate moved into mito?  Why? How? Pyruvate is moved into mitochondria (from cytoplasm) Why? This is where the 2 nd step occurs (specific enzymes are in mito) Serves as a checkpoint Uses active transport and transport proteins. ○ Why? Pyruvate is a charged molecule!

30 Formation of Acetyl CoA

31 Krebs Cycle Requirements  Pyruvic acid (3C acid)  Acetyl coenzyme A  4 NAD +  1 ADP  1 FAD  Double this list for each glucose

32 Krebs Cycle Products  3 CO 2  Acetyl CoA  4 NADH  1 FADH 2  1 ATP  Double this list for each glucose Made from pyruvate LOADS of energy stored in these molecules Krebs Cycle Intro

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34 Krebs Cycle notes  Notice: Only 1 ATP made per cycle Produces most of the cell's energy in the form of NADH and FADH 2  Does NOT require O 2

35 Comment about ATP  The ATPs produced directly in Krebs Cycle and Glycolysis are by: Substrate-level phosphorylation  The P group is transferred from a substrate to ADP Making ATP

36 At this point…  After the Krebs and glycolysis cycles, the cell has made a total of 4 ATP. Remember: some ATP had to be used to power the cycles.  Most energy (at this point) comes from NADH and FADH 2

37 Electron Transport System  ETC/S or Electron Transport Chain  This is a collection of proteins that are structurally linked  Located in inner membrane of mito Folding of mito (cristae) allows for lots of places (large surface area!) for ETC to occur

38 ETC/S  Uses sets of Cytochromes Fe (Iron)-containing proteins to pass electrons  The Cytochromes alternate between Red and Ox forms and pass electrons down to O 2 Remember: LEO, GER; LEO the lion goes GER Losing Electrons is Oxidation; Gaining Electrons is Reduction

39 As e- moves down the ETC, free energy decreases

40 ETC/S  Function: Convert NADH and FADH 2 into ATP  Location: Mitochondria cristae/folds

41 ETC Requirements  NADH or FADH 2  ADP O2O2 We finally see the need/requirement of Oxygen

42 ETC Products  NAD + and FAD  ATP (LOTS!!!) H2OH2O Remember: Water was also produced during glycolysis ETC explanation

43 ETC - ATP Yields  Each NADH  3 ATP  Each FADH 2  2 ATP 34 ATP  TOTAL: 34 ATP

44 Chemiosmotic Hypothesis  ETC energy is used to move H + (protons) across the mito/cristae membrane  ATP is generated as the H + diffuse back into the matrix

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46 ATP Synthase Enzyme  An enzyme that uses the flow of H + to make ATP  Works like an ion pump in reverse, or like a waterwheel under the flow of H + “water”  Power source: H+ concentration difference on opposite sides of mitochondrial membrane

47 Oxidative Phosphorylation  ATP synthase uses oxidative phosphorylation to make ATP during ETC  Uses H ions to make ATP and water (using Oxygen)

48 ATP Synthase

49 Alcoholic Fermentation  Done by yeast A kind of fungus  Used in brewing beer, winemaking, and baking CO 2 bubbles generated give: ○ Bread a rising effect ○ Wine/Beer the carbonated effect

50 Alcoholic Fermentation  Uses only Glycolysis  An incomplete oxidation - energy is still left in the products (alcohol)  Does NOT require O 2  Produces ATP (when O 2 is not available)

51 Alcohol

52 Lactic Acid Fermentation  Uses only Glycolysis  An incomplete oxidation - energy is still left in the products (lactic acid)  Does NOT require O 2  Produces ATP (when O 2 is not available)

53 Lactic acid

54 Lactic Acid Fermentation  Done by human muscle cells under oxygen debt Lactic Acid is a toxin and can cause soreness and stiffness in muscles Oxygen intake can’t keep up with sugar breakdown  Used in dairy industry (yogurt/cheese)  Also used to produce methanol and acetone

55 Fermentation - Summary  Way of using up NADH so Glycolysis can still run  Provides ATP to a cell even when O 2 is absent

56 Fermentation *Alcoholic OR *Lactic acid

57 Aerobic vs Anaerobic  Aerobic - Rs with O 2  Anaerobic - Rs without O 2  Aerobic - All three Rs steps  Anaerobic - Glycolysis only

58 Strict vs. Facultative  Strict - can only do Rs this one way Either aerobic OR anaerobic-NOT both!  Facultative - can switch types depending on O 2 availability Ex - yeast

59 Question??  Since yeast can do both aerobic and anaerobic Rs, which is the better process if given a choice? Hint: Check the ATP yields from both processes.

60 ATP yields by Rs type  Anaerobic - Glycolysis only gets 2 ATPs per glucose  Aerobic - Glycolysis, Krebs, and ETC. Generates many more ATPs per glucose.

61 Aerobic ATP yield  Glycolysis - 2 ATPS, 2 NADHs  Krebs - 2 ATPS, 8 NADHs, 2 FADH 2  Each NADH = 3 ATP  Each FADH 2 = 2 ATP

62 Aerobic ATP Sum  10 NADH x 3 = 30 ATPs  2 FADH 2 x 2 = 4 ATPs  2 ATPs (Gly) = 2 ATPs  2 ATPs (Krebs) = 2 ATPs  Max = 38 ATPs per glucose

63 However...  Some energy (2 ATP) is used in shuttling the NADH and pyruvate from Glycolysis into the mitochondria  Actual ATP yield ~ 36/glucose

64 Yeast  Would rather do aerobic Rs; This has 18x more energy per glucose than anaerobic  But, anaerobic will keep you alive if oxygen is not present.

65 Importance of Rs  Convert food to ATP Living orgs use ATP to fuel body processes Ex: reproduction, cell division  Provides materials for use in other cellular pathways

66 Other Respiration Items of Importance  Alcohol Industry - almost every society has a fermented beverage  Baking Industry - many breads use yeast to provide bubbles to raise the dough

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68 Alcohol Matching Game! Sugar Cane Gin Barley Rum Grapes Wine Juniper Cones Vodka Agave Leaves Beer Rice Tequila Potatoes Saki

69 Summary  Identify the basic chemical equation for cellular respiration.  Identify the main reaction sequences of cellular respiration.  Recognize the location, function, requirements, and products, for each cellular respiration reaction.  Recognize and be able to discuss the chemiosmotic model for ATP generation.  Recognize the reactions and importance of fermentation.  Contrast and compare aerobic and anaerobic respiration.  Identify the biological and commercial importances of respiration.

70 Exclusion Statements  You do NOT need to memorize the steps in glycolysis and the Krebs cycle, the structures of the molecules, or the names of the enzymes that are involved.  You do NOT need to memorize the names of the specific electron carriers in the electron transport chain (ETC).


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