2/4/17. Cellular Metabolism. Metabolism. Cellular Metabolism. Consists of all of the chemical reactions that take place in a cell.

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Metabolism Cellular Metabolism Consists of all of the chemical reactions that take place in a cell. Can be reactions that break things down. (Catabolism) Or reactions that build things up.

1 Metabolism Cellular Metabolism Consists of all of the chemical reactions that take place in a cell. Can be reactions that break things down. (Catabolism) Or reactions that build things up. (Anabolism) Biol 105 Read Chapter 3 (pages 63 69) Cellular Metabolism Some of the reactions provide energy for the cell in the form of ATP. Aerobic Cellular Respiration requires oxygen, produces carbon dioxide. Anaerobic Fermentation does not require oxygen, does not produce carbon dioxide. 1

Summary of Cellular Respiration Aerobic Cellular respiration Blood vessel Glucose Plasma membrane Electrons transferred by NADH Electrons transferred by NADH Electrons transferred by NADH Cytoplasm

2 Summary of Cellular Respiration Aerobic Cellular respiration Blood vessel Glucose Plasma membrane Electrons transferred by NADH Electrons transferred by NADH Electrons transferred by NADH Cytoplasm In aerobic cellular respiration cells take in sugar (glucose) and break it down to into carbon dioxide and water, this requires oxygen and produces CO 2. Carrier protein glucose pyruvate Transition Reaction and FADH 2 Citric Electron Acid Transport Cycle Chain This process produces energy in the form of ATP Oxygen Mitochondrion C 6 H 12 O 6 + 6O 2 6CO 2 +6H 2 O + Energy (ATP) Extracellular fluid +32 ATP 36 ATP +2 ATP +2 ATP = Figure 3.27 Aerobic Cellular respiration There are four steps in aerobic cellular respiration: Transition Reaction 3. Citric Acid Cycle (Krebs Cycle) 4. Electron Name, Location, Require O2?, Starting Molecule(s), Ending Molecule, #ATP, #NADH, #FADH2, #CO2 2

3 Cellular Respiration - Phase 1: Occurs in the cytoplasm. Does not require Oxygen Splits one glucose into two pyruvate molecules. Forms 2 Pyruvate Molecules Produces 2 ATP + 2 NADH Cellular Respiration - Starts with: 1 glucose (6 carbon molecule) (2 ATP) Ends with: 2 ATP 2 NADH 2 pyruvate (3 carbon molecule) (in cytoplasm) Cytoplasm During the first steps, two molecules of ATP are consumed in preparing glucose for splitting. Glucose Energyinvestment phase 2 ADP 2 ATP During the remaining steps, four molecules of ATP are produced. 4 ADP In Cytosol The two molecules of pyruvate then diffuse from the cytoplasm into the inner compartment of the mitochondrion, where they pass through a few preparatory steps (the transition reaction) before entering the citric acid cycle. 4 ATP 2 NAD + 2 NADH Energyyielding phase Two molecules of nicotine adenine dinucleotide 2 Pyruvate (NADH), a carrier of high-energy electrons, also are produced. Figure

4 Cellular Respiration Transition Reaction Phase 2: Transition Reaction (Intermediate Phase) Occurs within the mitochondria. Requires Oxygen. Coenzyme-A combines with pyruvate and a CO 2 is removed from each pyruvate. Forms 2 acetyl CoA molecules. Produces 2 NADH. Produces 2 CO 2. Transition Reaction Starts with: 2 pyruvate (3 carbon molecule) 2 Coenzyme A Ends with: 2 CO 2 2 NADH 2 Acetyl CoA (2 carbon molecule) Transition Reaction Transition Reaction (in mitochondrion) Cellular Respiration Citric acid cycle Phase 3: Citric Acid Cycle (Krebs Cycle) In Mitochondria Pyruvate (from glycolysis) One carbon (in the form of CO 2 ) is removed from pyruvate. A molecule of NADH is formed when NAD + gains two electrons and one proton. CO 2 NAD + NADH Coenzyme A (electron passes The two-carbon to electron molecule, called transport chain) an acetyl group, binds to coenzyme A (CoA), forming CoA acetyl CoA, which enters the Acetyl CoA citric acid cycle. Citric Acid Cycle Occurs in the mitochondria. Requires Oxygen. 2 Acetyl CoA enter the citric acid cycle and combine with oxaloacetate. Oxaloacetate re-forms. Produces: 2 ATP 2 FADH 2 6 NADH 4 CO 2 Figure

Citric Acid Cycle Also called the Krebs Cycle Starts with: 2 Acetyl CoA (2 carbon molecule) Oxaloacetate Ends with: 4 CO 2 2 ATP 6 NADH 2 FADH 2 Oxaloacetate In Mitochondria Citric Acid Cycle NADH

transport chain. Oxaloacetate Succinate NADH Acetyl CoA Citric Acid Cycle ATP ADP NAD + + Pi Acetyl CoA, the two-carbon compound formed during the transition reaction, enters the citric acid cycle.

5 Citric Acid Cycle Also called the Krebs Cycle Starts with: 2 Acetyl CoA (2 carbon molecule) Oxaloacetate Ends with: 4 CO 2 2 ATP 6 NADH 2 FADH 2 Oxaloacetate In Mitochondria Citric Acid Cycle NADH NAD + FADH 2 Malate FAD Citric Acid Cycle (in mitochondrion) The citric acid cycle also yields several molecules of FADH 2 and NADH, carriers of high-energy electrons that enter the electron transport chain. Oxaloacetate Succinate NADH Acetyl CoA Citric Acid Cycle ATP ADP NAD + + Pi Acetyl CoA, the two-carbon compound formed during the transition reaction, enters the citric acid cycle. CoA CoA Citrate CO 2 leaves cycle NAD + NADH α-ketoglutarate CO 2 leaves cycle The citric acid cycle yields One ATP from each acetyl CoA that enters the cycle, for a net gain of two ATP. Figure 3.25 NADH and FADH NADH and FADH 2 are important carriers of electrons 5

Cellular Respiration Phase 4: Electron Electrons of FADH 2 and NADH are transferred from one protein to another, until they reach oxygen. Requires oxygen. Releases energy that results in 32 ATP.

Electron Electron (inner membrane of mitochondrion) Inner Membrane of Mitochondria High NAD + NADH 2e The molecules of NADH and FADH 2 produced by earlier phases of cellular respiration pass their

6 Cellular Respiration Phase 4: Electron Electrons of FADH 2 and NADH are transferred from one protein to another, until they reach oxygen. Requires oxygen. Releases energy that results in 32 ATP. The Big Pay Off Electron NADH and FADH 2 are important carriers of electrons. They donate electrons to the electron transport chain. At the end of the chain oxygen accepts the electrons. Electron Electron (inner membrane of mitochondrion) Inner Membrane of Mitochondria High NAD + NADH 2e The molecules of NADH and FADH 2 produced by earlier phases of cellular respiration pass their electrons to a series of protein molecules embedded in the inner membrane of the mitochondrion. As the electrons are transferred from one protein to the next, energy is released and used to make ATP. Potential energy FADH 2 FAD 2e 2e Membrane proteins 2e Eventually, the electrons are passed to oxygen, which combines with two hydrogens to form water. 2e H 2 O Low Energy released is used for synthesis of ATP 2 H O 2 Figure

The Big Pay Off Electron Electron produces ATP using the ATP Synthase protein. The Electron produces 32 molecules of ATP. How is ATP made using the ETC 1.

7 The Big Pay Off Electron Electron produces ATP using the ATP Synthase protein. The Electron produces 32 molecules of ATP. How is ATP made using the ETC 1. In the mitochondria NADH and FADH 2 donate electrons to the electron transport chain (ETC). 2. Oxygen is the final electron acceptor from the ETC. 3. The ETC uses the energy from the electrons to transport H + against the concentration gradient, transporting them from the lumen of the mitochondria to the inter-membrane space. How is ATP made using the ETC 4. ATP Synthase allows the H + to flow down it s concentration gradient back to the lumen of the mitochondria. 5. The H + flowing through the ATP Synthase provides the energy for the ATP Synthase to catalyze the reaction of ADP + P ATP. 7

8 Summary of Cellular Respiration Summary of Cellular Respiration One molecule of glucose is broken down and 36 ATP are generated. Oxygen is used by the electron transport chain it accepts electrons from the end of the ETC. Carbon dioxide is produced by the Transition Reaction and the Citric Acid Cycle. Table 3.5 Summary of Cellular Respiration : Starts the process by taking in glucose. Produces 2 ATP & 2 NADH. The Transition Reaction: Produces 2 CO 2 and 2 NADH. The Citric Acid Cycle: Produces 2 ATP but also produces 6 NADH and 2 FADH 2. Summary of Cellular Respiration Electron transport chain Takes electrons from NADH and FADH 2 and uses them to produce ATP using the ATP Synthase protein. Requires oxygen: Oxygen is the final electron acceptor on the electron transport chain. One glucose can produce a total of 36 ATP 8

requires oxygen is Aerobic Cellular Respiration.

9 Sources of Energy Complex Carbohydrates must first be broken down into glucose before entering glycolysis H 2N CH C R O OH Fats and proteins enter the process at different steps Respiration Movie Animation Oxygen Cellular respiration that requires oxygen is Aerobic Cellular Respiration. Sometimes organisms, including humans, need to produce energy without using oxygen. When you need energy quick, or if there is not enough O 2 then the cell will use Anaerobic Fermentation. 9

Anaerobic Fermentation Anaerobic Fermentation: Use the anaerobic pathway to produce ATP from glycolysis without the Transition Reaction, Citric Acid Cycle or the ETC Anaerobic Fermentation Breakdown

10 Anaerobic Fermentation Anaerobic Fermentation: Use the anaerobic pathway to produce ATP from glycolysis without the Transition Reaction, Citric Acid Cycle or the ETC Anaerobic Fermentation Breakdown of glucose without oxygen. Takes place entirely in the cytoplasm. It is very inefficient - results in only two ATP. Fermentation in Animals When cells need energy quick they will use this pathway for a short time. 2 pyruvic acid + 2 NADH 2 lactate (lactic acid) and 2 NAD +. End result = lactate and 2 ATP produced (from glycolysis) and NAD + is regenerated 10

11 What is the starting molecule of glycolysis? What is the starting molecule of glycolysis? 1. Acetyl CoA 2. Protein 25% 25% 25% 25% 1. Acetyl CoA 2. Protein 25% 25% 25% 25% 3. Glucose 4. Pyruvate (pyruvic acid) 3. Glucose 4. Pyruvate (pyruvic acid) Acetyl CoA Protein Glucose Pyruvate (pyruvic acid) Acetyl CoA Protein Glucose Pyruvate (pyruvic acid) Which stage produces CO 2 Which stage produces CO Electron 3. Transition 4. Citric acid Cycle 5. Both 3 and 4 20% 20% 20% 20% 20% Electron 3. Transition 4. Citric acid Cycle 5. Both 3 and 4 20% 20% 20% 20% 20% Transition Citric acid Cycle Both 3 and 4 Transition Citric acid Cycle Both 3 and 4 11

12 Which stage uses O 2 Which stage uses O Citric Acid (Krebs) Cycle 3. Electron 33% 33% 33% Citric Acid (Krebs) Cycle 3. Electron 33% 33% 33% Krebs Cycle Krebs Cycle Which stage produces the most NADHs Which stage produces the most NADHs Citric Acid (Krebs) Cycle 3. Electron 33% 33% 33% Citric Acid (Krebs) Cycle 3. Electron 33% 33% 33% Krebs Cycle Krebs Cycle 12

13 Which stage produces the most ATP Which stage produces the most ATP Krebs Cycle 33% 33% 33% Krebs Cycle 33% 33% 33% 3. Electron 3. Electron Krebs Cycle Krebs Cycle Read Ch 4 Important Concepts What is Cellular respiration and Anaerobic Fermentation and what are the differences between them. What are the four steps of aerobic cellular respiration, what happens in each step, what are the starting molecules, what comes out of each step, where in the cell does each step occur, how many ATP and NADH/FADH 2 are produced in each step. Important Concepts Describe in detail how is ATP made using the electron transport chain What is the role of ATPsynthase, H +, O 2, NADH and FADH 2 and the electron transport chain in ATP production? Know the overall picture of cellular respiration (summary slides) 13

14 Important Concepts What is the role of oxygen in cellular respiration, what steps produce carbon dioxide What is anaerobic fermentation, what steps are involved in fermentation, what end products are produced in humans, is oxygen required? when is it used. Definitions Aerobic cellular respiration, anaerobic fermentation, ATP synthase, metabolism 14

Cellular Metabolism. Biol 105 Lecture 6 Read Chapter 3 (pages 63 69)

Cellular Metabolism. Biol 105 Lecture 6 Read Chapter 3 (pages 63 69) Cellular Metabolism Biol 105 Lecture 6 Read Chapter 3 (pages 63 69) Metabolism Consists of all of the chemical reactions that take place in a cell Metabolism Animation Breaking Down Glucose For Energy