Chapter 9 Cellular Respiration: Harvesting Chemical Energy

Is this a process of turning food into energy?

Rs - Equation C 6 H 12 O O 2 6 CO H 2 O and energy The energy is released from the chemical bonds in the complex organic molecules.

Respiration - Preview u The process of releasing Energy from food. u Food - Stored Energy in chemical bonds. u ATP - Useable Energy for cell work.

Focus of Chapter 1. Purpose - what is the reaction suppose to do? 2. Location - where is it at? 3. Requirements - what is needed to make it run? 4. Products - what does it produce?

Oxidation - definitions u Loss of electrons. u Loss of energy. u Loss of Hydrogens from Carbons.

Reduction - definitions u Gain of electrons. u Gain of energy. u Gain of Hydrogens to Carbons. Comment - be careful not to use “reduction” in lay terms.

Redox reactions

u Reactions are usually paired or linked together. u Look for these links as we study Rs. u Many of the reactions will be done by phosphorylation

Phosphorylation u Adding a phosphate group to a molecule. u The phosphate group adds “energy” to the molecule for chemical reactions.

Phosphorylation

Cell Respiration - parts 1. Glycolysis 2. Krebs Cycle 3. Electron Transport Chain

Glycolysis u Glyco- glucose. u -lysis: to split u Universal step in all Rs types. u Likely to earliest type of cell energy processes.

Glycolysis u Function - To split glucose and produce NADH and ATP. u Location - Cytoplasm.

Electron Carrier Compounds u Molecules that transport or shuttle electrons within the cell. u Exist it two forms: u Oxidized (ox) u Reduced (red)

NAD u Nicotinamide Adenine Dinucleotide NAD e - NADH NAD + = oxidized form NADH = reduced form

Glycolysis -Requirements u Glucose u 2 ATP u 4 ADP u 2 NAD +

Glycolysis - Products u 2 Pyruvic Acids (a 3C acid) u 2 ADP u 4 ATP u 2 NADH

Net Result u 2 ATP per glucose u 2 NADH

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Energy Investment Phase

Energy Harvest Phase

Krebs Cycle u Also called: u Citric Acid Cycle u Tricarboxylic Acid Cycle

Krebs Cycle u Function: Oxidize pyruvic acid to CO 2 u Produce NADH and FADH 2 u Location: Mitochondria matrix

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Formation of Acetyl CoA

Krebs Cycle -Requirements u Pyruvic acid (3C acid) u Coenzyme A u 4 NAD + u 1 ADP u 1 FAD u Double this list for each glucose.

Krebs Cycle - Products u 3 CO 2 u Acetyl CoA u 4 NADH u 1 ATP u 1 FADH 2 u Double this list for each glucose.

Krebs Cycle u Produces most of the cell's energy in the form of NADH and FADH 2 u Does NOT require O 2

Comment u The ATPs produced directly in Krebs Cycle and in Glycolysis are by: u Substrate-level phosphorylation u The Pi group is transferred from a substrate to ADP.

Electron Transport Chain u ETC or Electron Transport System (ETS). u A collection of proteins that are structurally linked into units.

ETC u Uses sets of Cytochromes, Fe containing proteins to pass electrons. u The Cytochromes alternate between RED and OX forms and pass electrons down to O 2

ETC u Function: Convert NADH and FADH 2 into ATP. u Location: Mitochondria cristae.

ETC - Requirements u NADH or FADH 2 u ADP uO2uO2

ETC - Products u NAD + and FAD u ATP uH2OuH2O

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ETC - ATP Yields u Each NADH -- 3 ATP u Each FADH ATP

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

ATP Synthase u Uses the flow of H + to make ATP. u Works like an ion pump in reverse, or like a waterwheel under the flow of H + “water”.

Alcoholic Fermentation u Done by yeast, a kind of fungus.

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

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

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Lactic Acid Fermentation u Done by human muscle cells under oxygen debt. u Lactic Acid is a toxin and causes soreness and stiffness in muscles.

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

Aerobic vs Anaerobic u Aerobic - Rs with O 2 u Anaerobic - Rs without O 2 u Aerobic - All three Rs steps. u Anaerobic - Glycolysis only.

Strict vs. Facultative u Strict - can only do Rs this one way. u Facultative - can switch Rs types depending on O 2 availability. Ex - yeast

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

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

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

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

However... u Some energy is used in shuttling the NADH from Glycolysis into the mitochondria. u Actual ATP yield ~ 36/glucose

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

Importance of Rs u Convert food to ATP. u Provides materials for use in other cellular pathways.

Other Importances of Respiration u Alcohol Industry - almost every society has a fermented beverage. u Baking Industry - many breads use yeast to provide bubbles to raise the dough.

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

Question u Why is the alcohol content of wine always around 12-14%? u Alcohol is toxic and kills the yeast at high concentrations.

Swiss Cheese u Holes are bubbles of CO 2 from fermentation.

Summary u Know the 3 main reactions of Rs and the 4 required items for each. u Appreciate the importances of Rs.

Rs Lab Report u Use data sheet for the three temperatures to make the graph.  Show changes as  mmHg. This will give you a positive slope.

Lab Report u Answer the 9 questions. u On #5, use the entire 30 minutes for calculating the rate.

Osmosis Lab Report u Table 1 & 7 questions u Graph dialysis bag results u Use class data set u Use a best-fit line or a trendline u Answer the 4 questions

u Graph potato results u Use class data set u Use a best-fit line or a trendline u Answer the 7 questions u Assume the temperature was 22 o C