Transcript Energy
Announcements ● Tutoring Center SCI I, 407 M 12-3, 5:30-6:30; W 8-9, 5:30-6:30, Th 8-12, 6-7; F 8-9 ● MasteringBiology Assignment due Tuesday 4/19 ● Exam I Tuesday 4/19 ● Scantron ABF-10-ID-200A Vacuoles Vacuoles are membranous sacs – Two types are the contractile vacuoles of protists and the central vacuoles of plants Central vacuole Contractile vacuoles (a) Contractile vacuoles in a protist (b) Central vacuole in a plant cell Plant Cells Not in animal cells Cytoskeleton Mitochondrion Central vacuole Nucleus Cell wall Rough endoplamsic reticulum (ER) Chloroplast Ribosomes Plasma membrane Smooth endoplasmic reticulum (ER) Plasmodesmata Golgi apparatus Plant Cells Plant cells are encased by cell walls Walls of two adjacent plant cells Vacuole Plasmodesmata (channels between cells) Chloroplasts Chloroplasts are the sites of photosynthesis, the conversion of light energy to chemical energy Inner and outer membranes of envelope Granum Space between membranes Stroma (fluid in chloroplast) Conservation of Energy Energy is defined as the capacity to perform work. Kinetic energy is the energy of motion. Potential energy is stored energy. On the platform, the diver has more potential energy. Climbing the steps converts kinetic energy of muscle movement to potential energy. Diving converts potential energy to kinetic energy. In the water, the diver has less potential energy. Energy Conversion Fuel rich in chemical energy Energy conversion Waste products poor in chemical energy Heat energy Gasoline Combustion Kinetic energy of movement Oxygen Energy conversion in a car Carbon dioxide Water Heat energy Food Oxygen Cellular respiration ATP Energy for cellular work Energy conversion in a cell Carbon dioxide Water Food Calories A calorie is the amount of energy that raises the temperature of one gram of water by 1 degree Celsius. Food Food Calories Cheeseburger 295 Spaghetti with sauce (1 cup) 241 Baked potato (plain, with skin) 220 Fried chicken (drumstick) 193 Bean burrito 189 Pizza with pepperoni (1 slice) 181 Peanuts (1 ounce) 166 Apple 81 Garden salad (2 cups) 56 Popcorn (plain, 1 cup) 31 Broccoli (1 cup) 25 (a) Food Calories (kilocalories) in various foods Food Calorie Consumption Activity Food Calories consumed per hour by a 150-pound person* Running (7min/mi) Dancing (fast) 510 Bicycling (10 mph) 490 Swimming (2 mph) 408 Walking (3 mph) 245 Dancing (slow) 204 Playing the piano 73 Driving a car 61 Sitting (writing) 28 979 *Not including energy necessary for basic functions, such as breathing and heartbeat (b) Food Calories (kilocalories) we burn in various activities ATP and Cellular Work Main types of (cellular) work: mechanical transport chemical The Structure of ATP – ATP (adenosine triphosphate) • Consists of adenosine plus a tail of three phosphate groups • Is broken down to ADP and a phosphate group, releasing energy Energy Triphosphate Adenosine P ATP P P Diphosphate Adenosine ADP P P P Phosphate (transferred to another molecule) ATP and Cellular Work Motor protein ATP ADP P ADP P ADP P Protein moved (a) Motor protein performing mechanical work Transport protein Solute P P ATP Solute transported (b) Transport protein performing transport work P ATP X P Y X Y ADP Reactants Product made (c) Chemical reactants performing chemical work P Enzymes – Metabolism is the total of all chemical reactions in an organism. – Most metabolic reactions require the assistance of enzymes, proteins that speed up chemical reactions. Induced Fit: Every enzyme is very selective, catalyzing a specific reaction. Activation Energy – Activation energy • Activates the reactants • Triggers a chemical reaction – Enzymes lower the activation energy for chemical reactions. Activation energy barrier Reactant Energy level Energy level Enzyme Reactant Products (a) Without enzyme Activation energy barrier reduced by enzyme Products (b) With enzyme Enzyme Inhibitors Substrate Active site (a) Enzyme and substrate binding normally Enzyme Inhibitor Active site (b) Enzyme inhibition by a substrate imposter (c) Enzyme inhibition By a molecule that Causes the active site to change shape Substrate Enzyme Active site Substrate Inhibitor Enzyme Traffic Across Membranes • • • • Passive transport Active transport Exocytosis Endocytosis Traffic Across Membranes • Diffusion – a process in which molecules move from an area of high concentration to an area of low concentration Molecules of dye Net diffusion Membrane Net diffusion (a) Passive transport of one type of molecule Equilibrium Traffic Across Membranes Animal cell H 2O H 2O H 2O Normal Lysing H 2O Flaccid (wilts) (a) Isotonic solution Shriveled Plasma membrane H O 2 Plant cell H 2O H 2O H 2O Turgid Shriveled (b) Hypotonic solution (c) Hypertonic solution Traffic Across Membranes –Active transport requires energy to move molecules across a membrane. Lower solute concentration Solute ATP Higher solute concentration Traffic of Large Molecules –Exocytosis is the secretion of large molecules within vesicles. Outside of cell Plasma membrane Cytoplasm Traffic of Large Molecules –Endocytosis takes material into a cell within vesicles that bud inward from the plasma membrane. MEMBRANE TRANSPORT Passive Transport (requires no energy) Active Transport (requires energy) Higher solute concentration Solute Water Solute Solute Diffusion Facilitated diffusion Osmosis Higher water concentration Higher solute concentration (lower solute concentration) Solute ATP Lower solute concentration Lower water concentration (higher solute concentration) Lower solute concentration