Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint ® Lecture Slides for Essential Biology, Second Edition & Essential Biology with Physiology Neil Campbell, Jane Reece, and Eric Simon Presentation prepared by Chris C. Romero Cellular Respiration: Harvesting Chemical Energy

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Bacteria are used to produce yogurt, sour cream, pepperoni, and cheese Both carbon monoxide and cyanide kill by disrupting cellular respiration

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings All the energy in all the food you eat can be traced back to sunlight If you exercise too hard, your muscles shut down from a lack of oxygen

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings When you exercise BIOLOGY AND SOCIETY: FEELING THE “BURN” –Muscles need energy in order to perform work –Your cells use oxygen to release energy from the sugar glucose

Copyright © 2004 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

Copyright © 2004 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

Copyright © 2004 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

Copyright © 2004 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

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Photosynthesis Producers and Consumers –Light energy from the sun powers a chemical process that makes organic molecules –This process occurs in the leaves of terrestrial plants

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Autotrophs –“Self-feeders” –Plants and other organisms that make all their own organic matter from inorganic nutrients Heterotrophs –“Other-feeders” –Humans and other animals that cannot make organic molecules from inorganic ones

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Producers –Biologists refer to plants and other autotrophs as the producers in an ecosystem Consumers –Heterotrophs are consumers, because they eat plants or other animals Figure 6.2

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings The ingredients for photosynthesis are carbon dioxide and water –CO 2 is obtained from the air by a plant’s leaves –H 2 O is obtained from the damp soil by a plant’s roots Chloroplasts rearrange the atoms of these ingredients to produce sugars (glucose) and other organic molecules –Oxygen gas is a by-product of photosynthesis Chemical Cycling Between Photosynthesis and Cellular Respiration

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Both plants and animals perform cellular respiration –Cellular respiration is a chemical process that harvests energy from organic molecules –Cellular respiration occurs in mitochondria The waste products of cellular respiration, CO 2 and H 2 O, are used in photosynthesis

Copyright © 2004 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

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings 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

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings 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

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Figure 6.4 Breathing Lungs Muscle cells Cellular respiration

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings 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

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings 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

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Chemical reactions that transfer electrons from one substance to another are called oxidation-reduction reactions Redox Reactions –Redox reactions for short

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings The loss of electrons during a redox reaction is called oxidation The acceptance of electrons during a redox reaction is called reduction

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Unnumbered Figure 6.2 [Oxygen gains electrons (and hydrogens)] Oxidation [Glucose loses electrons (and hydrogens)] GlucoseOxygenCarbon dioxide Water Reduction

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings RS IS NECESSARY IN ALL LIVING CELLS. PLANTS ARE WELL KNOWN FOR PS, BUT THEY MUST ALSO REPIRE IN ORDER TO SURVIVE. PS - OCCURS ONLY IN PLANT CELLS CONTAINING CHLOROPHYLL DURING THE DAYLIGHT HOURS. RS - OCCURS IN ALL OF A PLANT’S LIVING CELLS

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings PLANTS NEED ENERGY TO PERFORM MANY ESSENTIAL FUNCTIONS OF LIFE: GROWTH, REPAIR, NUTRIENT MOVEMENT, REPRODUCTION, & NUTRIENT TRANSPORT. WHY IS RS NECESSARY?

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Cellular respiration is an example of a metabolic pathway –A series of chemical reactions in cells –building or degradation process 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

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings A Road Map for Cellular Respiration Cytosol Mitochondrion High-energy electrons carried by NADH High-energy electrons carried mainly by NADH Glycolysis Glucose 2 Pyruvic acid Krebs Cycle Electron Transport Figure 6.7

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Glycolysis

Copyright © 2004 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 A molecule of glucose is split into two molecules of pyruvic acid Stage 1: Glycolysis

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Figure 6.8 Glucose 2 Pyruvic acid

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Krebs Cycle

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Stage 2: The Krebs Cycle The Krebs cycle completes the breakdown of sugar

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings In the Krebs cycle, pyruvic acid from glycolysis is first “prepped” into a usable form, Acetyl-CoA Figure 6.10 CoA Pyruvic acid Acetic acid Coenzyme A Acetyl-CoA (acetyl-coenzyme A) CO 2

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings 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

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Figure 6.11 Input Acetic acid ADP 3 NAD  FAD Krebs Cycle Output 2 CO

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Electron Transport Electron Transport

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Stage 3: Electron Transport Electron transport releases the energy your cells need to make the most of their ATP

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings 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

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Figure 6.12 Protein complex Electron carrier Inner mitochondrial membrane Electron flow Electron transport chain ATP synthase

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings The Versatility of Cellular Respiration Cellular respiration can “burn” other kinds of molecules besides glucose –Diverse types of carbohydrates –Fats –Proteins

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Figure 6.13 Food Polysaccharides FatsProteins SugarsGlycerolFatty acidsAmino acids Amino groups Glycolysis Acetyl- CoA Krebs Cycle Electron Transport

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Adding Up the ATP from Cellular Respiration Figure 6.14 Cytosol Mitochondrion Glycolysis Glucose 2 Pyruvic acid 2 Acetyl- CoA Krebs Cycle Electron Transport by direct synthesis by direct synthesis by ATP synthase Maximum per glucose:

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings 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

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings 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

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Glycolysis is the metabolic pathway that provides ATP during fermentation –Pyruvic acid is reduced by NADH, producing NAD+, which keeps glycolysis going –In human muscle cells, lactic acid is a by-product

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Figure 6.15a 2 ADP+ 2 Glycolysis Glucose 2 NAD  2 Pyruvic acid + 2 H  2 NAD  2 Lactic acid (a) Lactic acid fermentation

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings 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

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Figure 6.15b 2 ADP+ 2 2 ATP Glycolysis Glucose 2 NAD  2 Pyruvic acid 2 CO 2 released + 2 H  2 NAD  2 Ethyl alcohol (b) Alcoholic fermentation

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings The food industry uses yeast to produce various food products Figure 6.16

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Ancient bacteria probably used glycolysis to make ATP long before oxygen was present in Earth’s atmosphere EVOLUTION CONNECTION: LIFE ON AN ANAEROBIC EARTH –Glycolysis is a metabolic heirloom from the earliest cells that continues to function today in the harvest of food energy

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings SUMMARY OF KEY CONCEPTS Chemical Cycling Between Photosynthesis and Cellular Respiration Visual Summary 6.1 Sunlight Heat Photosynthesis Cellular respiration

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings 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)

Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings The Metabolic Pathway of Cellular Respiration Visual Summary 6.3 GlucoseOxygenWater Energy