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How Cells Harvest Chemical Energy

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Presentation on theme: "How Cells Harvest Chemical Energy"— Presentation transcript:

1 How Cells Harvest Chemical Energy
Chapter 9 How Cells Harvest Chemical Energy Introduction to Cell Metabolism Glycolysis Aerobic Cell Respiration Anaerobic Cell Respiration

2 Breathing and Cell Respiration are related
CO2 Lungs Muscle cells carrying out CO2 Bloodstream O2 CELLULAR RESPIRATION Sugar + O2  ATP + CO2 + H2O

3 Cellular Respiration uses oxygen and glucose to produce
Carbon dioxide, water, and ATP. Glucose Oxygen gas Carbon dioxide Water Energy

4 How efficient is cell respiration?
Energy released from glucose banked in ATP Energy released from glucose (as heat and light) Gasoline energy converted to movement 100% About 40% 25% Burning glucose in an experiment “Burning” glucose in cellular respiration Burning gasoline in an auto engine

5 Reduction and Oxidation OILRIG
Oxidation is losing electrons Reduction is gaining electrons Loss of hydrogen atoms Energy Glucose Gain of hydrogen atoms Glucose gives off energy and is oxidized

6 Reduction and Oxidation OILRIG
Gain or loss of electrons is often in the form of hydrogen. The hydrogen is then passed to a coenzyme such as NAD+

7 Reduction and Oxidation
What are some common co-enzymes? NAD+ and FAD NAD H  NADH + H+ FAD H  FADH2 Remember that H = 2 electrons and 2H+

8 Reduction and Oxidation
These co-enzymes are very important for cell respiration because they transfer high-energy electrons to electron transport systems (ETS).

9 Reduction and Oxidation
As the electrons move from carrier to carrier, energy is released in small quantities. Electron transport system (ETS)

10 Generation of ATP There are two ways to generate ATP Chemiosmosis Substrate-Level Phosphorylation

11 Generation of ATP Chemiosmosis Cells use the energy released by “falling” electrons in the ETS to pump H+ ions across a membrane Uses the enzyme ATP synthase.

12 Generation of ATP Chemiosmosis

13 Generation of ATP Substrate Level Phosphorylation Enzyme ATP can also be made by transferring phosphate groups from organic molecules to ADP Adenosine substrate Adenosine product Figure 6.7B

14 Generation of ATP Substrate Level Phosphorylation Enzyme ATP can also be made by transferring phosphate groups from organic molecules to ADP Adenosine substrate Adenosine product Figure 6.7B

15 Glycolysis General Outline No Oxygen Anaerobic Oxygen Aerobic
Glucose Glycolysis No Oxygen Anaerobic Oxygen Aerobic Pyruvic Acid Transition Reaction Fermentation Krebs Cycle ETS 38 ATP

16 Glycolysis Where? The cytosol What? Breaks down glucose to pyruvic acid

17 Glycolysis Energy In: 2 ATP Energy Out: 4 ATP NET 2 ATP
Steps – A fuel molecule is energized, using ATP. Glucose 1 3 Step Glycolysis 1 Glucose-6-phosphate 2 Fructose-6-phosphate Energy In: 2 ATP 3 Fructose-1,6-diphosphate Step A six-carbon intermediate splits into two three-carbon intermediates. 4 4 Glyceraldehyde-3-phosphate (G3P) (TRIOSE PHOSPHATE) 5 Step A redox reaction generates NADH. 5 1,3-Diphosphoglycerate (2 molecules) 6 Steps – ATP and pyruvic acid are produced. 3-Phosphoglycerate (2 molecules) Energy Out: 4 ATP 6 9 7 2-Phosphoglycerate(2 molecules) 8 2-Phosphoglycerate(2 molecules) NET 2 ATP 9 Pyruvic acid (2 molecules per glucose molecule)

18 Glycolysis General Outline No Oxygen Anaerobic Oxygen Aerobic
Glucose Glycolysis No Oxygen Anaerobic Oxygen Aerobic Pyruvic Acid Transition Reaction Fermentation Krebs Cycle ETS 36-38 ATP

19 General Outline of Aerobic Respiration
Glycolysis Transition Reaction Krebs Cycle Electron Transport System

20 Transition Reaction/Pre-Krebs/Link Reaction: Occurs in the Matrix
Each pyruvic acid molecule is broken down to form CO2 and a two-carbon acetyl group, which enters the Krebs cycle. An Oxidative Decarboxylation Reaction: Pyruvic Acid Acetyl CoA

21 General Outline of Aerobic Respiration
Glycolysis Transition Reaction Krebs Cycle Electron Transport System

22 Krebs Cycle Where? In the Mitochondria What? Uses Acetyl Co-A to generate ATP, NADH, FADH2, and CO2.

23 Krebs Cycle

24 Krebs Cycle

25 General Outline of Aerobic Respiration
Glycolysis Krebs Cycle Electron Transport System

26 ELECTRON TRANSPORT CHAIN
Electron Transport System Protein complex Intermembrane space Electron carrier Inner mitochondrial membrane Electron flow Mitochondrial matrix ELECTRON TRANSPORT CHAIN ATP SYNTHASE Figure 6.12

27 Electron Transport System

28 CHEMIOSMOSIS The coupling of ATP synthesis to electron transport via a concentration gradient. It is the MECHANISM for oxidative phosphorylation in Aerobic C.R. and Photosynthesis

29 Electron Transport System
For each glucose molecule that enters cellular respiration, chemiosmosis produces up to 38 ATP molecules

30 Overview of Aerobic Respiration

31 Glycolysis General Outline No Oxygen Anaerobic Oxygen Aerobic
Glucose Glycolysis No Oxygen Anaerobic Oxygen Aerobic Pyruvic Acid Transition Reaction Fermentation Krebs Cycle ETS 38 ATP

32 Fermentation Requires NADH generated by glycolysis. Where do you suppose these reactions take place? Yeast produce carbon dioxide and ethanol Muscle cells produce lactic acid Only a 2 ATP are produced per glucose

33 Fermentation


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