© 2010 Pearson Education, Inc. Lectures by Chris C. Romero, updated by Edward J. Zalisko PowerPoint ® Lectures for Campbell Essential Biology, Fourth Edition – Eric Simon, Jane Reece, and Jean Dickey Campbell Essential Biology with Physiology, Third Edition – Eric Simon, Jane Reece, and Jean Dickey Chapter 6 Cellular Respiration: Obtaining Energy from Food
© 2010 Pearson Education, Inc. Producers and Consumers Plants and other autotrophs (self-feeders): –Make their own organic matter from inorganic nutrients. Autotrophs are producers because ecosystems depend upon them for food. Heterotrophs (other-feeders): –Include humans and other animals that cannot make organic molecules from inorganic ones. Heterotrophs are consumers because they eat plants or other animals.
© 2010 Pearson Education, Inc. Plant and animal cells perform cellular respiration, a chemical process that: –Primarily occurs in mitochondria –Harvests energy stored in organic molecules –Uses oxygen –Generates ATP
© 2010 Pearson Education, Inc. The waste products of cellular respiration are: –CO 2 and H 2 O –Used in photosynthesis
© 2010 Pearson Education, Inc. Animals perform only cellular respiration. Plants perform: –Photosynthesis and –Cellular respiration
Sunlight energy enters ecosystem Photosynthesis Cellular respiration C 6 H 12 O 6 Glucose O 2 Oxygen CO 2 Carbon dioxide H 2 O Water drives cellular work Heat energy exits ecosystem ATP Figure 6.2
CELLULAR RESPIRATION: AEROBIC HARVEST OF FOOD ENERGY Cellular respiration is: –The main way that chemical energy is harvested from food and converted to ATP –An aerobic process—it requires oxygen © 2010 Pearson Education, Inc.
Cellular respiration and breathing are closely related. –Cellular respiration requires a cell to exchange gases with its surroundings. –Cells take in oxygen gas. –Cells release waste carbon dioxide gas. –Breathing exchanges these same gases between the blood and outside air. © 2010 Pearson Education, Inc.
C 6 H 12 O 6 CO 2 O2O2 H2OH2O GlucoseOxygenCarbon dioxide Water 6 6 Reduction Oxidation Oxygen gains electrons (and hydrogens) Glucose loses electrons (and hydrogens) Figure 6.UN02
© 2010 Pearson Education, Inc. The Role of Oxygen in Cellular Respiration Cellular respiration can produce up to 38 ATP molecules for each glucose molecule consumed. During cellular respiration, hydrogen and its bonding electrons change partners. –Hydrogen and its electrons go from sugar to oxygen, forming water. –This hydrogen transfer is why oxygen is so vital to cellular respiration.
© 2010 Pearson Education, Inc. The Versatility of Cellular Respiration In addition to glucose, cellular respiration can “burn”: –Diverse types of carbohydrates –Fats –Proteins
Food PolysaccharidesFatsProteins SugarsGlycerolFatty acidsAmino acids Glycolysis Acetyl CoA Citric Acid Cycle Electron Transport ATP Figure 6.12
© 2010 Pearson Education, Inc. 38 ATP WITH OXYGEN
© 2010 Pearson Education, Inc. FERMENTATION: ANAEROBIC HARVEST OF FOOD ENERGY Some of your cells can actually work for short periods without oxygen. Fermentation is the anaerobic (without oxygen) harvest of food energy.
© 2010 Pearson Education, Inc. Glycolysis during Anaerobic conditions: –Does not require oxygen –Produces 2ATP molecules for each glucose broken down to pyruvic acid
Glucose 2 ATP 2 NAD 2 NADH 2 NAD 2 H 2 ADP 2 Pyruvic acid 2 Lactic acid Glycolysis INPUTOUTPUT 2 P Figure 6.14
© 2010 Pearson Education, Inc. Observation: Muscles produce lactic acid under anaerobic conditions. Question: Does the buildup of lactic acid cause muscle fatigue? Hypothesis: The buildup of lactic acid would cause muscle activity to stop. Experiment: Tested frog muscles under conditions when lactic acid could and could not diffuse away. The Process of Science: Does Lactic Acid Buildup Cause Muscle Burn?
Battery Force measured Battery Force measured Frog muscle stimulated by electric current Solution prevents diffusion of lactic acid Solution allows diffusion of lactic acid; muscle can work for twice as long Figure 6.15
© 2010 Pearson Education, Inc. Results: When lactic acid could diffuse away, performance improved greatly. Conclusion: Lactic acid accumulation is the primary cause of failure in muscle tissue. However, recent evidence suggests that the role of lactic acid in muscle function remains unclear.
© 2010 Pearson Education, Inc. Fermentation in Microorganisms Fermentation alone is able to sustain many types of microorganisms. The lactic acid produced by microbes using fermentation is used to produce: –Cheese, sour cream, and yogurt dairy products –Soy sauce, pickles, olives –Sausage meat products
© 2010 Pearson Education, Inc. Yeast are a type of microscopic fungus that: –Use a different type of fermentation –Produce CO 2 and ethyl alcohol instead of lactic acid This type of fermentation, called alcoholic fermentation, is used to produce: –Beer –Wine –Breads
Glucose 2 ATP 2 NAD 2 NADH 2 NAD 2 2 P 2 Pyruvic acid 2 Ethyl alcohol Glycolysis INPUTOUTPUT 2 CO 2 released Bread with air bubbles produced by fermenting yeast Beer fermentation 2 ADP HH Figure 6.16