General Biology 1004 Chapter 5 Lecture Handout, Summer 2005 Dr. Frisby

Transcription

1 Slide 1 CHAPTER 5 The Working Cell PowerPoint Lecture Slides for Essential Biology, Second Edition & Essential Biology with Physiology Presentation prepared by Chris C. Romero Copyright 2004 Pearson Education, Inc. publishing as Benjamin Cummings Neil Campbell, Jane Reece, and Eric Simon Slide 2 BIOLOGY AND SOCIETY: STONEWASHING WITHOUT THE STONES The sturdy cotton fabric denim has been worn because of its toughness and appeal Stonewashing jeans with pumice stone can damage the fabric Recently the enzyme cellulase has been used to achieve better results Figure 5.1 Slide 3 SOME BASIC ENERGY CONCEPTS Energy makes the world go around

2 Slide 4 Kinetic energy is the energy of motion Potential energy is stored energy 2 High potential energy 1 Conversion of kinetic energy to potential energy 3 Conversion of potential energy to kinetic energy 4 Low potential energy Figure 5.2 Slide 5 Energy can be changed from one form to another Slide 6 Heat is Entropy

3 Slide 7 Scientists use the term entropy as a measure of disorder, or randomness Slide 8 Chemical energy Chemical Energy Slide 9 Living cells and automobile engines use the same basic process to make chemical energy do work Fuel rich in chemical energy Heat energy Waste products poor in chemical energy Gasoline Combustion Kinetic energy of movement Carbon dioxide Oxygen (a) Energy conversion in a car Water Figure 5.3a

4 Slide 10 Heat energy Food Cellular respiration Carbon dioxide Oxygen Energy for cellular work (b) Energy conversion in a cell Water Figure 5.3b Slide 11 Cellular respiration Slide 12 Food Calories A calorie is the amount of energy that raises the temperature of 1 gram of water by 1 degree Celsius

5 Slide 13 The kilocalorie is 1,000 calories The unit used to measure the energy in food Figure 5.4a Slide 14 The energy of calories in food is burned off by many activities Figure 5.4b Slide 15 ATP AND CELLULAR WORK The chemical energy of organic molecules is released in cellular respiration to make ATP in the mitochondria

6 Slide 16 The Structure of ATP ATP (adenosine triphosphate) Energy Adenosine Adenosine Phosphate transferred to other molecules Figure 5.5 Slide 17 Phosphate Transfer ATP can energize other molecules by transferring phosphate groups Slide 18 Three Main Kinds of Cellular Work Motor protein Protein moved (a) Mechanical work Transport protein Solute (b) Transport work Solute transported ATP Reactants (c) Chemical work Product made Figure 5.6

7 Slide 19 The ATP Cycle Cellular work spends ATP ATP is recycled from ADP and phosphate through cellular respiration Slide 20 ATP functions in what is called energy coupling, or the ATP cycle Cellular respiration: chemical energy harvested from fuel molecules Energy for cellular work Figure 5.7 Slide 21 ENZYMES Metabolism is defined as the many chemical reactions that occur in organisms Few metabolic reactions occur without the assistance of enzymes

8 Slide 22 Activation Energy Activation energy Slide 23 Enzymes Activation energy barrier Enzyme Reactants Products (a) Without enzyme (b) With enzyme Figure 5.8 Slide 24 Induced Fit Each enzyme is very selective

9 Slide 25 Each enzyme recognizes a specific substrate Slide 26 Enzymes can function over and over again Active site Enzyme (sucrase) 1 Enzyme available with empty active site Substrate (sucrose) 2 Substrate binds to enzyme Fructose Glucose 4 Product are released 3 Substrate is converted to products Figure 5.9 Slide 27 Enzyme Inhibitors Enzyme inhibitors Substrate Active site Inhibitor Substrate Active site Enzyme (a) Normal enzyme action Enzyme (b) Enzyme inhibition by a substrate imposter Figure 5.10a, b

10 Slide 28 Other inhibitors Active site Substrate Inhibitor Enzyme (c) Enzyme inhibition by a molecule that causes the active site to change shape Figure 5.10c Slide 29 MEMBRANE TRANSPORT Working cells must control the flow of materials Slide 30 Passive Transport: Diffusion Across Membranes Molecules contain heat energy

11 Slide 31 Diffusion is one result of the movement of molecules Slide 32 Molecules of dye Membrane Equilibrium (a) Passive transport of one type of molecule Equilibrium (b) Passive transport of two types of molecules Figure 5.11 Slide 33 Another type of passive transport is facilitated diffusion, the transport of some substances by specific transport proteins that act as selective corridors

12 Slide 34 Osmosis and Water Balance in Cells Osmosis is the passive transport of water across a selectively permeable membrane Hypotonic solution Hypertonic solution Isotonic solutions Sugar molecule (solute) Selectively permeable membrane Osmosis (net movement of water) Figure 5.12 Slide 35 A hypertonic solution A hypotonic solution An isotonic solution Slide 36 Water Balance in Animal Cells The survival of a cell depends on its ability to balance water uptake and loss Animal cell Normal Lysing Shriveled Plasma membrane Plant cell Flaccid (wilts) Turgid Shriveled (a) Isotonic solution (b) Hypotonic solution (c) Hypertonic solution Figure 5.13

13 Slide 37 Osmoregulation is the control of water balance in animals Slide 38 Water Balance in Plant Cells Water balance in plant cells is different Figure 5.14 Slide 39 Active Transport: the Pumping of Molecules Across Membranes Active transport requires energy to move molecules across a membrane Lower solute concentration Solute Higher solute concentration Figure 5.15

14 Slide 40 Exocytosis and Endocytosis: Traffic of Large Molecules Exocytosis Outside cell Plasma membrane Cytoplasm (a) Exocytosis Figure 5.16a Slide 41 Endocytosis (b) Endocytosis Figure 5.16b Slide 42 In phagocytosis ( cellular eating ) a cell engulfs a particle and packages it within a food vacuole In pinocytosis ( cellular drinking ) a cell gulps droplets of fluid by forming tiny vesicles Pseudopod of amoeba Food being ingested Figure 5.17

15 Slide 43 Receptor-mediated endocytosis Slide 44 The Role of Membranes in Cell Signaling LDL particle Phospholipidcoat Protein Receptor protein Cholesterol Plasma membrane Liver cell Cholesterol processed Figure 5.18 Slide 45 Cellular communication The signal transduction pathway

16 Slide 46 Outside cell Inside cell Reception Transduction Response Receptor protein Signal transduction pathway Hydrolysis of glycogen releases glucose for energy Epinephrine (adrenaline) from adrenal glands Plasma membrane Figure 5.19 Slide 47 EVOLUTION CONNECTION: EVOLVING ENZYMES Organisms use many different enzymes Slide 48 The processes of natural selection and directed evolution

17 Chapter 5 Study Objectives 1. Explain how enzymes can be used t produce stonewashed jeans. 2. Define the terms: energy, kinetic energy, the principle of conservation of energy and potential energy. 3. Explain the relationship between heat and entropy. 4. Compare the processes by which a car and a human use fuel to perform work. Explain why the human process is more efficient. 5. Compare the amount of energy in a calorie to that found in a kilocalorie. Which is most commonly used on food labels? 6. Explain how ATP drives work in chemical reactions in cells. 7. Explain the process of energy coupling in cells. 8. Explain how enzymes are able to speed up chemical reactions. 9. Define the terms: metabolism, enzyme, activation energy, substrate, active site, induced fit, and feedback regulation. 10. Explain how enzymes can act as inhibitors and poisons. 11. Distinguish between the following pairs of terms: diffusion versus osmosis, passive transport versus active transport, hypertonic versus hypotonic, endocytosis versus exocytosis, and phagocytosis versus pinocytosis. 12. Explain how enzymes can be produced by directed evolution. 13. Explain how directed evolution and natural selection are similar and different.