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68 Cards in this Set
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What is the basic definition of metabolism?
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a highly coordinated set of transformations which interconvert matter and energy in a living system - all reactions taking place in a living organism
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What four main things does metabolism do?
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1. derives energy from fuel molecules (highly reduced molecules)
2. converts nutrients into the building blocks of proteins, lipids, carbohydrates, and nucleic acids 3. assembles the building blocks into macromolecular structures 4. forms and degrades molecules needed by cells |
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Anabolic Processes
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produce product molecules with higher free energy than the reactants used. processes are biosynthetic and the change in free energy is pos.- it requires the input of energy.
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Catabolic Processes
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break down molecules into products which have lower free energy than starting molecules. processes are degradative and the change in free energy is negative - they release energy to be used in anabolic processes
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catabolism does what to the environment?
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it destroys the environment to provide energy and building blocks for the organism
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Chemotrophs
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Derive their energy by degrading nutrients to waste. There are limits to the number of such organisms which can exist within an environment. They utilize a wide range of nutrients, they break these nutrients down into very few intermediates.
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Catabolic processes converge to a ________
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small number of core molecules
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What happens to the potential energy of the complex molecules taken in during catabolism?
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it is released to sustain the organism
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The end products of catabolic processes are what?
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waste and basic building blocks
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Stage 1 of Catabolism
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The hydrolysis of complex molecules (eg. proteins, lipids) to their building blocks. It is considered to take place outside the body (not in a cell) in the GI tract
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Stage 2 of catabolism
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The covnersion of building blocks (eg. AA, monosaccharides)to acetyl CoA. Takes place in the cytoplasm of cells. Releases energy to the cell (change in G is -). It is nonoxidative. Sugars of many types are broken down to organic acids. Nitrogen is removed from AAs and carbon skeletons are formed. Fats are broken down to fatty acids and glycerol
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What things 3 are broken down to produce Acetyle Coenzyme A in stage II metabolism?
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1. organic acids
2. carbon skeletons of most AAs 3. Fatty acids |
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Stage II metabolism forms a single product, what is it?
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Acetyl Coenzyme A
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Stage III metabolism
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acetyl coenzyme A is oxidized through many steps through a cyclic pathway. electrons derived from these oxidation steps reduce NAD+ to NADH. Carbon atoms are oxidized to CO2 and electrons from NADH reduce oxygen to water.
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Where does stage III metabolism occur?
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mitochondria
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What are the waste products of stage III metabolism?
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CO2 and water
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Biochemistry takes place in structures which maintain a _____ environment within an _______ macrosystem.
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reduced, oxidized
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fuels are what types of biomolecules?
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reduced
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control of the redox state is important, what is used to control it?
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energy
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oxidation of fuels yields what? Oxidation of the cellualr environment is a factor in what?
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energy, death
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Is the energy released through a catabolic process dependent of independent of the pathway utilized?
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independent
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nonliving systems generally function as what type of engines?
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heat engines - they produce large amounts of heat on oxidation, heat overcomes the activation energy, reactions occur at high temperature, and the heat (thermal heat) is released all at once
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T or F Living systems release the same amount of energy as nonliving systems.
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T
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How is energy released in living systems?
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In small steps, not all at once. The energy released is captured via coupled reactions. Chemical bonds form.
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T or F Anabolic and Catabolic Processes are Coupled
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T
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The energy released in catabolic pathways is often used to what?
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build up a concentration gradient or form new chemical bonds
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Explain how catabolism occurs in many small steps
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the product of one reaction is the reactant for another linked step. the product has just slightly less free energy than the reactant
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pathways are formed b/c of what? pathways form within what?
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localization and common intermediates;compartments
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Are living systems isothermal?
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yes
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The intermediates in metabolic pathways are called what?
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metabolites ; catabolic intermediates are called catabolites and anabolic intermediates are called anabolites
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The energy required for biosynthesis is derived from what?
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coupled reactions
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Explain how biosynthesis starts and proceeds
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it starts with a very few building blocks and proceeds with very small steps. anabolic pathways link needed biosynthetic steps
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To maximize efficiency anabolic and catabolic processes are what?
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highly regulated
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If a catabolic and anabolic process are related they must be _______
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compartmentalized
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How are steps with high change in G regulated?
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actively regulated (allosteric regulation)- flux determining steps
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How are steps with low change in G regulated?
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the concentrations of reactants and products regulate the process - equilibrium controlled step
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electrons derived from oxidation are stored in what?
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NADH
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electrons utilized for reductions are stored in what?
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NADPH
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T or F Enzymes use NADH not NADPH
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F some enzymes use NADH and some use NADPH
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What are essential to structural compartmentalization in a cell?
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membranes
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Acetyl CoA is produced by enzymes that are localized where? After the reaction, Acetyl CoA is released where?
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the interface of the cytoplasm and the mitochondria; the mitochondria
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Creating a hole in a membrane results in what?
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Opens a channel to the environment-destroying concentration gradients. Without concentration gradients cell cannot do work and die.
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How are biological membranes inherited?
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maternally
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Transport across artificial membranes involves what?
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simple diffusion - the rate follows Fick's Law : J = D[change in P/change in X]
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Diffusion across biological membranes may be _______ or ______
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simple or facilitated(some type of mechanism to get across the membrane)
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The kinetics of facilitated diffusion show _____
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saturation
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Facilitated diffusion implies the formation of what?
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an EP (enzyme permeate) complex
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The kinetics of facilitated diffusion matches the kinetics of what?
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enzymes
J = VmaxPo/[Km + Po] |
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facilitation involves what?
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channels, transporters, or group translocators
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Channels are what?
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protein complexes which have specificity for permeants and augment the simple diffusion of permeants with low or limited diffusion coefficients
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Transporters
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generally soluble molecules which carry the permeant across the membrane
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Group Translocators
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move permeants through a mechanism involving group modification
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In both simple and facilitated diffusion the Po is always _____ than the Pi
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higher
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In simple diffusion the kinetics are _____ and in facilitated diffusion the kinetics are _____
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linear, saturable
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the rate of transport is dependent on what?
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the concentration gradient [change in P (Po/Pi)/change in X]
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Active transport is coupled to what?
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ATP hydrolysis, PMF and chemical or electrical gradients
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Facilitated diffusion can only transport from ______ conc. to ______ conc.
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high to low
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How is active transport different from facilitated diffusion?
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active transport can accumulate a permeant inside or exclude it outside the cell
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Can the kinetics of active transport be differentiated from facilitated diffusion?
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no
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Types of active transport
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1. uniport systems
2. symport systems 3. antiport systems |
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uniport systems
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must couple to a source of energy other than a concentration gradient to drive transport
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symport systems
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use another gradient to provide the energy for transport, the direction is the same
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antiport systems
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use another gradient in the opposite direction to drive transport
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sugar does what to odontoblasts?
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it turns off their pumps, allowing bacterial products to penetrate and cause dental caries - adequate micromineral intake may counter sugar
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Explain how odontoblasts are fluid transporters?
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a fluid pump utilizes ATP to transport fluid from the plasma through the odontoblastic tubules. this fluid is extruded through pores in the enamel and flushes bacterial acids and enzymes from the enamel subsurface
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explain how all living systems are built on the same principles
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1. most living organisms utilize the same biomolecules
2. most living organisms utilize similar enzymes 3. living organisms are interdependent |
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What describes the interrelationships that exist between chemotrophs and phototrophs?
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the carbon cycle
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What describes the interrelationships that exists between nitrogen fixers and delinkers?
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the nitrogen cycle
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