Energy and Metabolism fall 2017 posted

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Information about Energy and Metabolism fall 2017 posted

Published on September 23, 2017

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. Slide2: Life Runs on Energy! Slide4: Brain activity consumes roughly 20% of one's resting metabolic rate, which is 1300 kilocalories on average. Thus an average person burns 10.8 kcal per hour Slide7: As long as you are alive your cells are working! 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 Slide19: 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. Slide20: 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 Slide22: 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 Slide24: 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 Slide26: 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) + Slide27: Activation energy Minimum amount of energy required to start a reaction Enzymes speed up reactions by lowering activation energy. Slide28: Reactants: 2 H 2 + O 2 Activation energy Energy Difference in energy between reactants and products Products: 2 H 2 O Time Slide29: Three Phosphate Groups Adenine Ribose Mr. Trade Tech Slide30: 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 Slide31: 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! Slide33: 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 Slide34: An enzyme’s particular substrates bind at its active site Substrate A reactant molecule that is specifically acted upon by an enzyme Slide35: 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 Slide36: Stomach Liver Digestive System Slide37: 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 Slide38: 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 Slide39: 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 Slide40: 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 Slide41: 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 Slide42: 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 Slide43: 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 Slide45: 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 Slide46: selectively permeable membrane Osmosis Slide47: 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 Slide49: 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 Slide50: 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 ? Slide53: 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. Slide54: 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 Slide55: 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 Slide56: 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 Slide57: 2 3 Extracellular Fluid glucose 1 Cytoplasm lipid bilayer Passive Transport Slide58: Sarcoplasmic Reticulum Cytoplasm calcium A B C Active Transport Slide59: 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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