Energy and Metabolism spring 2014

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Information about Energy and Metabolism spring 2014

Published on March 15, 2014

Author: acocil


Energy and Metabolism: Energy and Metabolism First Exam Next Week Chapters 1,2,3 and 4 Bio Intro, Biomolecules, Cell and Cell Metabolism. PowerPoint Presentation: Life Runs on Energy! PowerPoint Presentation: As long as you are alive your cells are working! PowerPoint Presentation: Obama likes tacos One-Way Flow of Energy: One-Way Flow of Energy Living things maintain their organization by harvesting energy Energy flows in one direction through the biosphere (starting mainly from the sun) then into and out of ecosystems PowerPoint Presentation: Light energy radiating from the sun reaches Earth. Producers capture some of it by converting it to chemical energy. They and all other organisms use chemical energy to drive cellular work. ENERGY IN PRODUCERS plants and other self-feeding organisms nutrient cycling CONSUMERS animals, most fungi, many protists, bacteria ENERGY OUT With each conversion, there is a one- way fl ow of a bit of energy back to the environment, mainly in the form of heat. PowerPoint Presentation: Energy The capacity to do work Energy can be converted from one form to another, but cannot be created or destroyed – energy disperses spontaneously Thermodynamics: Thermodynamics First law of thermodynamics Energy cannot be created or destroyed It can be converted from one form to another and thus transferred between objects or systems Second law of thermodynamics Energy tends to disperse spontaneously A bit disperses at each energy transfer, usually in the form of heat PowerPoint Presentation: Cells store and retrieve energy by making and breaking chemical bonds in metabolic reactions Some reactions require a net input of energy – others end with a net release of energy PowerPoint Presentation: Chemical bonds hold energy – the amount depends on which elements take part in the bond Cells store energy in chemical bonds by running energy-requiring reactions, and access energy by running energy-releasing reactions Chemical Reactions: Chemical Reactions Reaction Process of chemical change Reactant Molecule that enters a reaction Product A molecule remaining at the end of a reaction PowerPoint Presentation: Reactants Products 2 H 2 (hydrogen) 2 H 2 O (water) 4 hydrogen atoms + 2 oxygen atoms 4 hydrogen atoms + 2 oxygen atoms O 2 (oxygen) + PowerPoint Presentation: 2 H 2 + O 2 Energy energy in energy out 2 H 2 O PowerPoint Presentation: Activation energy Minimum amount of energy required to start a reaction Enzymes speed up reactions by lowering activation energy. PowerPoint Presentation: Reactants: 2 H 2 + O 2 Activation energy Energy Difference in energy between reactants and products Products: 2 H 2 O Time PowerPoint Presentation: Three Phosphate Groups Adenine Ribose Mr. Trade Tech PowerPoint Presentation: Energy carriers accept energy from energy-releasing reactions and deliver energy to energy-requiring reactions ATP (Adenosine triphosphate) Main energy carrier between reaction sites in cells PowerPoint Presentation: Phosphate-group transfers ( phosphorylation ) to and from ATP couple energy-releasing reactions with energy-requiring ones ATP is called The Energy Currency of Cells: ATP is called The Energy Currency of Cells ATP contains ribose! PowerPoint Presentation: Enzymes make chemical reactions proceed much faster than they would on their own Enzyme Protein or RNA that speeds a reaction without being changed by it PowerPoint Presentation: An enzyme’s particular substrates bind at its active site Substrate A reactant molecule that is specifically acted upon by an enzyme PowerPoint Presentation: Each enzyme works best within a characteristic range of temperature, pH, and salt concentration When conditions break hydrogen bonds, an enzyme changes its characteristic shape (denatures), and stops working PowerPoint Presentation: Stomach Liver Digestive System PowerPoint Presentation: Cofactor A metal ion or a coenzyme that associates with an enzyme and is necessary for its function Coenzyme An organic cofactor Unlike enzymes, may be modified by a reaction PowerPoint Presentation: Cells concentrate, convert, and dispose of most substances in enzyme-mediated reaction sequences Metabolic pathway Series of enzyme-mediated reactions by which cells build, remodel, or break down an organic molecule PowerPoint Presentation: Electron transfer chains allow cells to harvest energy in manageable increments Electron transfer chain An array of membrane-bound enzymes and other molecules that accept and give up electrons in sequence PowerPoint Presentation: For metabolism to work, a cell must keep its internal composition stable – even when conditions outside are greatly different Selective permeability Membrane property that allows some substances, but not others, to cross PowerPoint Presentation: Gases (such as oxygen and carbon dioxide), small nonpolar molecules, and water cross a bilayer freely. Other molecules and ions cannot cross a lipid bilayer on their own. lipid bilayer Selective Permeability of Cell Membranes PowerPoint Presentation: Concentration The number of molecules or ions per unit volume of a fluid Concentration gradient Difference in concentration of a substance between adjoining regions of fluid PowerPoint Presentation: Molecules or ions tend to follow their own concentration gradient and diffuse into an adjoining region of fluid in which they are less concentrated Diffusion Net movement of molecules or ions from a region of higher concentration to a region of lower concentration Diffusion Rate: Diffusion Rate How quickly a particular solute diffuses through a particular solution depends on five factors 1. Size 2. Temperature 3. Steepness of the concentration gradient 4. Charge 5. Pressure PowerPoint Presentation: Water molecules tend to diffuse in response to their own concentration gradient Osmosis Net diffusion of water molecules across a selectively permeable membrane between two fluids with different water concentrations PowerPoint Presentation: selectively permeable membrane Osmosis PowerPoint Presentation: Turgor counters osmosis Turgor Pressure that a fluid exerts against a wall, membrane, or other structure that contains it Osmotic pressure Amount of turgor that prevents osmosis into cytoplasm or other hypertonic fluid Osmosis and Tonicity: Osmosis and Tonicity Tonicity describes relative concentrations of solutes in fluids separated by a selectively permeable membrane Hypotonic: Low solute concentration relative to another fluid Hypertonic: High solute concentration relative to another fluid Isotonic: Same solute concentration relative to another fluid PowerPoint Presentation: Osmosis is the diffusion of water across a selectively permeable membrane from the region with a lower solute concentration (hypotonic) toward the region with a higher solute concentration (hypertonic) Osmosis will continue until the two fluids are isotonic, or until some pressure against the hypertonic fluid counters the movement PowerPoint Presentation: In multicelled organisms, the volume of the cell will change if the extracellular fluid is not isotonic Cells in hypertonic fluid shrink Cells in hypotonic fluid swell Maintaining the tonicity of extracellular fluids is an important part of homeostasis Osmosis, Tonicity and Selectively Permeable Membranes: Osmosis, Tonicity and Selectively Permeable Membranes ? PowerPoint Presentation: B Red blood cells immersed in an isotonic solution do not change in volume. The fl uid portion of blood is typically isotonic with cytoplasm. C Red blood cells immersed in a hypertonic solution shrivel up because more water diffuses out of the cells than into them. D Red blood cells immersed in a hypotonic solution swell up because more water diffuses into the cells than out of them. PowerPoint Presentation: Gases, water, and small nonpolar molecules can diffuse across a lipid bilayer Most other molecules and ions cross only with the help of transport proteins, which gives a cell or membrane-enclosed organelle control over which substances enter and exit PowerPoint Presentation: Each type of transport protein moves a specific ion or molecule across a membrane The types of transport proteins in a membrane determine which substances cross it Examples: glucose transporters, calcium pumps PowerPoint Presentation: Passive transport Concentration gradient drives a solute across a cell membrane through a transport protein Requires no energy input Active transport A transport protein use energy, usually from ATP, to pump a solute across a cell membrane against its concentration gradient PowerPoint Presentation: 2 3 Extracellular Fluid glucose 1 Cytoplasm lipid bilayer Passive Transport PowerPoint Presentation: Sarcoplasmic Reticulum Cytoplasm calcium A B C Active Transport PowerPoint Presentation: Co transporter Active transport protein that moves two substances across a membrane in opposite directions at the same time Example: sodium-potassium pump ATP powers an active transport protein that pumps Na + out of and K + into a cell Cotransport: Sodium-Potassium Pump: Cotransport: Sodium-Potassium Pump Membrane Trafficking: Membrane Trafficking Patches of membrane constantly move to and from the cell surface as vesicles that fuse with or pinch off from the plasma membrane The lipid bilayer reseals itself when the membrane is disrupted Endocytosis and Exocytosis: Endocytosis and Exocytosis Endocytosis Process by which a cell takes in a small amount of extracellular fluid by a ballooning inward of its cellular membrane Exocytosis Process by which a cell expels a vesicle’s contents to extracellular fluid by merging the vesicle with the plasma membrane Membrane Crossings: Membrane Crossings Endocytosis Phagocytosis: Phagocytosis Phagocytosis (“cell eating”) Endocytic pathway by which cells such as macrophages and other white blood cells engulf particles such as microbes or cellular debris Amoebas also are phagocytic cells Phagocytosis: Phagocytosis

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