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Cellular Respiration Process whereby cells breakdown glucose and other food molecules to release energy.

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Presentation on theme: "Cellular Respiration Process whereby cells breakdown glucose and other food molecules to release energy."— Presentation transcript:

1 Cellular Respiration Process whereby cells breakdown glucose and other food molecules to release energy.

2 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The efficiency of cellular respiration –Provides a high % of energy in a controlled manner Figure 6.2B Burning glucose in an experiment Energy released from glucose (as heat and light) 100% Energy released from glucose banked in ATP “Burning” glucose in cellular respiration About 40% Gasoline energy converted to movement Burning gasoline in an auto engine 25%

3 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings When you exercise BIOLOGY AND SOCIETY: FEELING THE “BURN” –Muscles need energy in order to perform work Enzymes in muscle cells help a cell use glucose and oxygen to produce ATP

4 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Aerobic metabolism –When enough oxygen reaches cells to support energy needs Anaerobic metabolism –When the demand for oxygen outstrips the body’s ability to deliver it

5 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Anaerobic metabolism –Without enough oxygen, muscle cells break down glucose to produce lactic acid –Lactic acid is associated with the “burn” associated with heavy exercise –If too much lactic acid builds up, your muscles give out

6 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Physical conditioning allows your body to adapt to increased activity –The body can increase its ability to deliver oxygen to muscles Long-distance runners wait until the final sprint to exceed their aerobic capacity Figure 6.1

7 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings ENERGY FLOW AND CHEMICAL CYCLING IN THE BIOSPHERE Fuel molecules in food represent solar energy –Energy stored in food can be traced back to the sun Animals depend on plants to convert solar energy to chemical energy –This chemical energy is in the form of sugars and other organic molecules

8 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 6.3 Sunlight energy Ecosystem Photosynthesis (in chloroplasts) Glucose Oxygen Carbon dioxide Cellular respiration (in mitochondria) Water for cellular work Heat energy

9 Energy and Food A large amount of energy is stored within the chemical bonds of food. Burning 1g glucose (C 6 H 12 O 6 ) releases 3811 C of heat. Calorie - amount of energy needed to raise the temperature of 1g of H 2 O 1ºC. Cells do not burn glucose, but gradually break it down to release the energy.

10 Cellular respiration CELLULAR RESPIRATION: AEROBIC HARVEST OF FOOD ENERGY –The main way that chemical energy is harvested from food and converted to ATP –This is an aerobic process—it requires oxygen

11 Cellular respiration and breathing are closely related –Cellular respiration requires a cell to exchange gases with its surroundings –Breathing exchanges these gases between the blood and outside air The Relationship Between Cellular Respiration and Breathing

12 Figure 6.4 Breathing Lungs Muscle cells Cellular respiration

13 Cellular Respiration Three Steps I.Glycolysis II.Krebs Cycle III.Electron Transport Chain

14 A common fuel molecule for cellular respiration is glucose –This is the overall equation for what happens to glucose during cellular respiration The Overall Equation for Cellular Respiration Unnumbered Figure 6.1 GlucoseOxygenCarbon dioxide WaterEnergy Cellular respiration can produce up to 38 ATP molecules for each glucose molecule consumed

15 ATP molecules are the key to energy coupling ATP molecules store energy during the process of cellular respiration ATP power nearly all forms of cellular work ATP the cell’s chemical energy

16 The Role of ATP Cellular money Cells “earn” ATP in exergonic reactions Cells “spend” ATP in endergonic reactions P PP ribose adenine

17 Hydrolysis breaks a phosphate group bond from the ATP molecules releasing energy The exergonic reaction supplies energy for cellular work Figure 5.4A Phosphate groups Adenine Ribose Adenosine triphosphate Hydrolysis Adenosine diphosphate (ADP) Energy Energy Coupling

18 Phosphorylation –How ATP powers cellular work Figure 5.4B Reactants Potential energy of molecules Products Protein Work

19 The ATP cycle Figure 5.4C Energy from exergonic reactions Dehydration synthesis Hydrolysis Energy for endergonic reactions

20 During cellular respiration, hydrogen and its bonding electrons change partners –Hydrogen and its electrons go from sugar to oxygen, forming water The Role of Oxygen in Cellular Respiration

21 Why does electron transfer to oxygen release energy? –When electrons move from glucose to oxygen, it is as though they were falling –This “fall” of electrons releases energy during cellular respiration Figure 6.5 Release of heat energy

22 Cell with Mitochondria (red spots)

23 Mitochondria Site of Krebs cycle and Electron Transport Chain

24 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings An overview of cellular respiration Figure 6.8 High-energy electrons carried by NADH GLYCOLYSIS GlucosePyruvic acid KREBS CYCLE ELECTRON TRANSPORT CHAIN AND CHEMIOSMOSIS Mitochondrion Cytoplasmic fluid

25 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Stage 1: Glycolysis A molecule of glucose is split into two molecules of pyruvic acid

26 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Glycolysis breaks a six-carbon glucose into two three-carbon molecules –These molecules then donate high energy electrons to NAD+, forming NADH

27 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Glycolysis makes some ATP directly when enzymes transfer phosphate groups from fuel molecules to ADP Figure 6.9 Enzyme

28 Cell with Mitochondria (red spots)

29 Mitochondria Site of Krebs cycle and Electron Transport Chain

30 An overview of cellular respiration Figure 6.8 High-energy electrons carried by NADH GLYCOLYSIS GlucosePyruvic acid KREBS CYCLE ELECTRON TRANSPORT CHAIN AND CHEMIOSMOSIS Mitochondrion Cytoplasmic fluid

31 Stage 2: The Krebs Cycle The Krebs cycle completes the breakdown of sugar

32 The Krebs cycle extracts the energy of sugar by breaking the acetic acid molecules all the way down to CO 2 –The cycle uses some of this energy to make ATP –The cycle also forms NADH and FADH 2

33 II. Krebs Cycle Process whereby pyruvate is broken down into CO 2 in a series of energy releasing reactions. Only occurs if O2 is present (aerobic respiration). Takes place within the mitochondria of the cell. Each pyruvate that goes through the cycle produces 1 ATP, 4 NADH, 1 FADH 2 and 3 CO 2 (2 X that amount for each glucose molecule).

34 An overview of cellular respiration Figure 6.8 High-energy electrons carried by NADH GLYCOLYSIS GlucosePyruvic acid KREBS CYCLE ELECTRON TRANSPORT CHAIN AND CHEMIOSMOSIS Mitochondrion Cytoplasmic fluid

35 Stage 3: Electron Transport Electron transport releases the energy your cells need to make the most of their ATP

36 The molecules of electron transport chains are built into the inner membranes of mitochondria –The chain functions as a chemical machine that uses energy released by the “fall” of electrons to pump hydrogen ions across the inner mitochondrial membrane –These ions store potential energy

37 When the hydrogen ions flow back through the membrane, they release energy –The ions flow through ATP synthase –ATP synthase takes the energy from this flow and synthesizes ATP

38 The Versatility of Cellular Respiration Cellular respiration can “burn” other kinds of molecules besides glucose –Diverse types of carbohydrates –Fats –Proteins

39 Pathways of molecular breakdown Figure 6.16 Food, such as peanuts PolysaccharidesFatsProteins SugarsGlycerolFatty acidsAmino acids Amino groups GlucoseG3P Pyruvic acid GLYCOLYSIS Acetyl CoA KREBS CYCLE ELECTRON TRANSPORT CHAIN AND CHEMIOSMOSIS

40 The path that electrons take on their way down from glucose to oxygen involves many stops NADH and Electron Transport Chains Figure 6.6 1/21/2 (from food via NADH) 2 H  2 e  Energy for synthesis of Electron transport chain 2 e  2 H  1/21/2

41 Cellular respiration is an example of a metabolic pathway –A series of chemical reactions in cells All of the reactions involved in cellular respiration can be grouped into three main stages –Glycolysis –The Krebs cycle –Electron transport The Metabolic Pathway of Cellular Respiration

42 FERMENTATION: ANAEROBIC HARVEST OF FOOD ENERGY Some of your cells can actually work for short periods without oxygen –For example, muscle cells can produce ATP under anaerobic conditions Fermentation –The anaerobic harvest of food energy

43 Human muscle cells can make ATP with and without oxygen –They have enough ATP to support activities such as quick sprinting for about 5 seconds –A secondary supply of energy (creatine phosphate) can keep muscle cells going for another 10 seconds –To keep running, your muscles must generate ATP by the anaerobic process of fermentation Fermentation in Human Muscle Cells

44 Various types of microorganisms perform fermentation –Yeast cells carry out a slightly different type of fermentation pathway –This pathway produces CO 2 and ethyl alcohol Fermentation in Microorganisms

45 The food industry uses yeast to produce various food products Figure 6.16

46 SUMMARY OF KEY CONCEPTS Chemical Cycling Between Photosynthesis and Cellular Respiration Visual Summary 6.1 Sunlight Heat Photosynthesis Cellular respiration

47 The Overall Equation for Cellular Respiration Visual Summary 6.2 Oxidation: Glucose loses electrons (and hydrogens) GlucoseCarbon dioxide Electrons (and hydrogens) Energy Oxygen Reduction: Oxygen gains electrons (and hydrogens)

48 The Metabolic Pathway of Cellular Respiration Visual Summary 6.3 GlucoseOxygenWater Energy

49 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Long-distance runners have many slow fibers in their muscles –Slow fibers break down glucose for ATP production aerobically (using oxygen) –These muscle cells can sustain repeated, long contractions How is a Marathoner Different from a Sprinter?

50 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Sprinters have more fast muscle fibers –Fast fibers make ATP without oxygen - - anaerobically –They can contract quickly and supply energy for short bursts of intense activity

51 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The dark meat is an example of slow fiber muscle –Leg muscles support sustained activity The white meat consists of fast fibers –Wing muscles allow for quick bursts of flight

52 Biosynthesis of macromolecules from intermediates in cellular respiration Figure 6.17 ATP needed to drive biosynthesis PolyscaccharidesFatsProteins KREBS CYCLE Acetyl CoA Pyruvic acid G3PGlucose GLUCOSE SYNTHESIS Amino groups Amino acidsFatty acidsGlycerolSugars Cells, tissues, organisms


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