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81 Cards in this Set
- Front
- Back
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Metabolism |
- refer to the sum of all chemicals reactions within a living organism |
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Catabolism |
- enzyme regulated chemical reactions that release energy - the breakdown of complex organic compounds into simpler ones - generally hydrolytic reactions: reactions which use water and in which chemical bonds are broken - provide building block for anabolic reactions and furnish the energy needed to drive anabolic reactions - ex: cells break down sugars into carbon dioxide and water - turn ADP, phosphate group, energy into ATP |
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Anabolism |
- enzyme regualted energy- requiring reactions - the building of complex organic molecules from simpler one - often involve dehydration synthesis: reactions that release water - endergonic: consume more energy than they produce - turn ATP into ADP, phosphate group, and energy |
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ATP consists of: |
- adenine, a ribose, and three phosphate groups |
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Metablic Pathways |
- sequence of chemical reactions - determined by enzymes which are in turn determined by the cell's genetic makeup |
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Collision Theory |
- explains how chemical reactions occur and how certain factors effect the rates of those reactions - all atoms, ions, and molecules are continuously moving are thus continuously colliding with one another - collision can disrupt their electron structures enough to break chemical bonds or form new bonds |
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Factors that Determine Whether a Collison will Cause a Chemical Reaction |
- the veolocities of the colliding particles - their energy - and their specific chemical configurations |
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Activation Energy |
- the collision energy required for a chemical reaction to be occur - the amount of energy needed to disrupt the stable electronic configuration of any specific molecule so that the electrons can be rearranged |
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Reaction Rate |
- the frequency of collisions containing suffiecient energy to bring about a reaction - depends on the number of reactants molecules at or above the activation energy level - to increase rate increase temperature because their movement increasing thus collision increases - collisions increase: when pressure, or concentration is increased |
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Catalyst |
- substances that can speed up chemical reactions without being permantely altered themselves |
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Enzymes |
- serves a biological catalyst - are specific - accelerate chemical reactions |
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Substrate |
- enzymes specific substance in whcih it reacts to - catalyzes one reaction |
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Active Site of Enzymes |
- a region that interacts with specific chemical substances |
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Enzyme- Substrate Complex |
- formed by the temporary binding of enzymes and reactants enables the collisions to be more effective and lowers the activation energy of the reaction |
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Turn Over Number |
- maximum number of substrate molecules an enzyme can converts to product each second - generally between 1 and 1,000 and can be as high as 500,000 |
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Apoenzyme |
- protein portion of the enzyme - inactive by themselves need a cofactor to be activated |
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Cofactor |
- nonprotein portion of the enzyme - if organic: coenzyme |
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Holoenzyme |
- an apoenzyme and a coenzyme together - whole active enzyme |
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Coenzyme |
- assists the enzyme by accepting atoms removed from the substrate or by donating atoms required by the substrate - some act as electron carriers, removing electrons from the substrate and donating them to other molecules in subsequent reactions - most important enzymes: NAD+ and NADP+ |
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NAD+ |
- primary envolved in catabolic reactions - function as electron carriers |
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NADP+ |
- primarly involved anablic reatins - function as electron carriers |
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FMN and FAD |
- electron carriers - |
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Coenzyme A |
- contains a derivative of pantothenic acid - plays an important role in the synthesis and breakdown of fats in as eries of oxidizing reactions called Krebs cycle |
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Enzyme Action Sequence |
1) suface of substrate contacts active site 2) Enzyme-substrate complex forms 3) the substrate molecules is transformed by the rearrangement of existing atoms, the breakdown of the substrate molecule or in combination with another substrate molecule 4) the transformed substrate molecules- products of reactions- are released from the enzyme molecule because they no longer fit in the activation site 5) the unchanged enzyme is not free to react with another substrate |
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Temperature and Enzymes |
- rate of most chemical reactions increase at the temperature increases - after the optimal temperature the rate of reaction decreases |
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Denaturation |
- the loss of its charactersitic three deminsional structure - involves the breakage of hydrogen bonds and other noncovalent bonds - changes the arrangement of amino acids in the active site, altering its shape and causing the enzymes to lose its catalytic ability - if enzyme loses its soubility and coagualtes the znumes cannot regain its original properties |
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pH and enzymes |
- when h+ concentration is changed dramatically the protiens three demensional structure is altered - acids alter a protein's structure because H+ competes with hydrogen and ionic bonds in an enzyme resulting in denaturation |
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Saturation |
- under high substrate concentration, all active site of enzymes are occupied by substrates or product molecules - increase in substrate concentration would not affect the reaction rate |
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Competitior Inhibitor |
- fill the active site of an enzyme and compete with the normal substrate for the active site - its shape and chemical structure are similar to those of the normal substrate - does not undergo reaction to create product - some bind irreversibly to amino acids in the active site, preventing any further interactions with the substrate - increase of substrate can overcome the competitive inhibitor |
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Noncompetitor Inhibitors |
- do not compete with the substrate for enzyme's active site; insteady they interact with another part of the enzyme |
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Allosteric Inhibition |
- the inhibitor binds to a site on the enzyme other than the substrate's binding site called the allosteric site - this binding causes the active site to change its shape making it nonfunctional - enzyme activity is reduced - in some cases, it actually initiate an enzyme rather than inhibit it |
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Feedback Inhibition or End Product Inhibition |
- allosteric inhibitors play a role in this - this control mechanism stops cell from making more of a substance that it needs and thereby wasting chemical resources - end products ends process from reoccuring - as the cell uses existing product, the first enzyme's allosteric site more often remains unbound and the pathway resumes activity |
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Ribozyme |
- type of RNA - function as catalysts have active sites that bind to substrates and are not used up in a chemical reaction - specifically act on strands of RNA by removing sections and splicing together the remaining pieces |
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Oxidation |
- the removal of electrons form an atom or molecule - reaction that often produces energy |
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Reduction |
- meaning that it gains an electron |
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Oxidaiton- Reduction Reaction |
- each time a substance is oxidized another is simultaneously reduced - pairing of these combinations - use them in catabolism to extract energy from nutrient molecules |
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Dehydrogenation Reactions |
- oxidations that involve the loss of hydrogren atoms - a molecule of NAD+ is reduced - NAD+ accepts two electrons and one proton |
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Phosphorylatin |
- the additon of P to a chemical compound - use three mechanisms of phosphorylation to generate ATP from ADP |
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Substrate Level Phosphorylation |
- ATP is usually generated when a high energy phosphate is directly transferred form a phosphoylated compound to ADP |
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Oxidative Phosphorylation |
- electrons are transferred from organic compounds to one group of an electron carriers (usually NAD+ and FAD) - electrons are then passed through a series of different electrons carries to molecules of oxygen - occurs in the plasma membrane, and in the inner mitochondrial membrane of eukaryotes |
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Electorn Transport Chain |
- the sequence of electron carriers used in oxidative phospholyation - the transfer of electrons from one carrier to the other releases energy, some of which is used to generate ATP from ADP through a process called chemiosmosis |
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Photophosphorylation |
- occurs only in photosythetic cells - which contain light trapping pigments such as chlorophylls - starts this process by converting light energy to chemical energy of ATP and NADPH which in turn are used to synthesize organic molecules - electron chain is involved |
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Carboydrate Catabolism |
- the breakdown of carbohydrates molecules to produce energy - glucose is the most common carbohydrate - can also cataboize various lipids and proteins for energy production |
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Process to Convert Glucose into Energy |
- cellular respiration - fermentation |
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Over View of the Processes |
1) Glycolysis is the oxidation of glucose to pyruvic aicd with the production of ATP and energy conataining NADH 2) Kerbs cycle is the oxidation of acetyl CoA (derivative of pyruvic acid) to carbon dioxide with the production of ATP, energy containing NADH, and other reduced elctron carrier FADH+ 3) In the Electron Transport System, NADH and FADH+ are oxidized, contributing the electrons they have carried from the substrate to a cascade of oxidation reduction reactions involving a series of additional electron carries. Energy form these reactions is used to generate a considerable amount of ATP, In respiration, most the ATP is gernated in the third step |
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Respiration |
- entire process can be thought as involving a flow of electrons from the energy rich glucose of molecule to the relatively enrgy poor CO2 and H2O molecules |
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Glycolysis |
- the oxidation of glucose to pyruvic acid, is usually the first stage in carbohydrate catabolism - six carbon sugars --> three carbon sugars - sugar is oxidized releasing energy, and their atoms are rearranged to form two molecules of pyruvic acid - NAD+ is reduced to NADH and there is a net production of four ATP molecules by substrate level phosphorylation but since two molecules are need to start glycolysis there is a net change of two molecules of ATP for each molecule of glucose that is oxidized |
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The Pentonse Phosphate Pathway |
- operates simultaneously glycolysis and provides a means of breakdown for five carbon sugars as well as glucose - key feature is that it produces important intermediate pentose used in the synthesis of nucleic acids, glucose from carbon dioxide in photosynthesis and certain amino acids - important producer of the reduced coenzyme NADPH from NADP+ - yields one ATP molecules from each molecules of glucose oxidized |
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Entner Doudoroff Pathway |
- produces two molecules of NADPH and one molecule of ATP for use in cellulr biosythetic reaactions - bacteria that have enzymes for this pathway can metabolize glucose without either glycolysis or the pentose phosphate pathway - found in gram negative bacteria |
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Cellular Respiration |
- defined as an ATP generating process in whcih molevules are oxidized and the final electron acceptir is an inorganic meolcuels |
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Areobic Respiration |
- the final acceptor is always oxygen |
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Anaerobic Respiration |
- the final accpeotr sin an inorganic molecule other than oxygen |
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Kerbs Cycle |
- series of biochemical reactions in which the large amount of potential chemical energy stored in acetyl CoA relreased step by step - a series of oxidations and reductions transger that potential energy in form of electrons to electron carrier coenzymes, cheifly NAD+ - pyruvic acid from gylcosis cannot enter this cycle directly and must lose one molecule of CO2 and become a two carbon compound |
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Decarboxylation |
- when a moleuvles of CO2 is removed form a compound |
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Acetyl Group |
- two carbon compound - attaches to coenzyme A through a high energy bond resulting complex known as acetyl CoA - during this reaction pyruvic acid is also oxidized and NAD+ is reduced to NADH |
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Kerbs Cycle Steps |
1) as acetyl CoA enters, CoA detaches from the acetyl group. The two carbon acetyl group combines with four carbon compound called oxaloacetic acid to form six carbon citric acid. Energy from the removal of CoA from the acetyl group is used to form the six carbon citric acid 2) oxidations generate NADH. 3) combine oxidations and decarboxylations to dispose of two carbon atoms that came form oxaloacetic acid. Carbons are released as CO2 and the oxidations generate NADH from NAD+ 4) During the second oxidation, CoA is added into the cycle forming compound succinyl CoA 5) ATP is produced by substrate- level phosphorylation. CoA is removed form succinyl CoA, leaving succinic acid 6) oxidation produced FADH2 7) Fumaric acid is formed 8) oxidation generates NADH and and converts malic acid to oxaloacetic acid |
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Electron Transport Chain |
- consits of a series of sequennce of carrier molecules that are capable of oxidation and reduction - as electrons are passed through the chain, there occurs a stepwise release of energy which is used to drive the chemiosmotic generation of ATP - eukaryotic cells: in the mitochondria - prokaryotic cells: in the plasma membrane |
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Flavoproteins |
- one of three types of carrier proteins in the electron transport chain - these proteins contain flavin, a coenzyme derived form riboflavin and are capable of performing alternating oxidations and reductions |
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Cytochromes |
- one of three types of carrier proteins in the electron transport chain - proteins with an iron containing group capable of existing alternately as reduced form and oxidative form |
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Ubiquinones or Coenzye Q |
- one of three types of carrier proteins in the electron transport chain - these are small nonprotein carriers |
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Basic Goal of Electorn Transport Chain |
- to release energy as electrons are transferred form higher energy compounds to lower energy compounds |
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Electron Transport Chain Steps |
1) transfer of high energy electrons form NADH to FMN. This transfer actually involves the passage of of a hydrogen atom with two electrons to FMN which then picks up an additonal H+ form surronding aqueous medium. As a result NADH is oxidized to NAD+ and FMN is reduced to FMNH2 2) FMNH2 passed 2H+ to the other side of the mitochondrial membrane and passes two electron to Q. As a result FMNH2 is oxidized into FMN. Q also picks up an additional 2H+ from the surrounding aqueous medium and releases it on the other side of the mitochondria 3) Electrons are passed successively from Q to other cytochromes. The last cychrome passes it electrons to molecular oxygen which becomes negatively charged and then picks up protons from the surrounding medium to form H20 |
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Chemiosmosis |
- the mechanism of ATP sythesis using the electron transport chain - the energy released when a substance moves along a gradient is used to synthesize ATP |
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Steps of Chemiosmosis |
1) energy electrons from NADH pass down the electron transport chain some of the carriers in the chain pump activaly trasnport protons across the membrane 2) Creates a concentration gradient. There is also an electrical charge gradient becasue the excess H+ on one side of the membrane makes the side positively charged. the resulting electrochemical gradient has potential energy 3) the protons on the side of the membrane with the higher proton concentration can diffuse across the membrane only through special protein channels that contain an enzyme called ATP synthase. When this flows occurs energy is released and is used by the enzyme to synthesize ATP from ADP |
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Fermentation |
1) process that releases energy form sugars or other organic molecules such as amino acids, organic acids, purines, and pyrimidines 2) process that does not require oxygen 3) process that does not require the use of the Krebs cycle or an electron transport chain 4) process that uses an organic molecule as the final acceptor 5) process that produces only small amount of ATP because much of the original energy in glucose remains in the chemical bonds of the organic end products such as lactic acid or ethanol |
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Lactic Acid Fermentation |
- in the first stage in glycolysis, a molecule of glucose is oxidized to two molecules of pyruvic acid. - this oxidation generates the energy that is used to form the two molecules of ATP - in the second step, the two molecules of pyruvic acid are reduced by two molecules of NADH to form two molecules of lactic acid - lactic acid is the final product and there is no further oxidation and most of the energy produced by the reaction remains stored in the lactic acid |
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Alcohol Fermentation |
- also begins with glycolysis of a molecule of glucose to yeild two molecules of pyruvic acid and tow molecules of ATP - in the next reaction, the two molecules of pyruvic acid converted to two molecules of acetaldehyde and two molecules of CO2 . The two molecules of acetaldehyde are next reduced by two molecules of NADH to form two molecules of ethanol - carried out by a number of bacteria and yeast |
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Homolactic |
- microbes that only produce lactic acid |
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Heterolactic |
- organisms that produce lactic acid as well as other acids or alcohols - often use pentose phosphate pathway |
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Deamination |
- the amino group an amino acid is removed and converted to ammonium ion which can be excreted from a cell |
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Fermentation Test |
- the test medium contains protein, a single carbohydrate, a pH indicator and an inverted tube, which is used to capture gas - bacteria inoculated in the tube can use the protein or carbohydrate as a carbon and energy source - if they catabolize the carbohydrate and produce acid the pH indicator changes color - some organisms produce gas as well as acid |
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Phototrophs |
- use light as their primary source of energy |
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Chemotrophs |
- depend on oxidation reduction reactions of inorganic or ogranic compounds for energy |
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Autrophs |
- use carbon dioxide for thier prinicple carbon source |
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Heterotrophs |
- require an organic carbon source |
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Photoautorophs |
- use light as a source of energy and carbon dioxide as their cheif source of carbon - include synthetic bacteria, algae, and green plants |
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Photoheterotrophs |
- use light as a source of enrgy but cannot convert carbon dioxide to sugar - rather they use as a source of carbon organic compounds such as alcohols, fatty acids, other organic acids, and carbohydrates |
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Chemoautorophs |
- use the electrons from reduced inroganic compounds a a source of energy and they use CO2 as thier prinicple source of carbon - |
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Chemoheterotrophs |
- specifically use the electrons form hydrogen atoms in organic compounds as their energy source - further classified by their source of organic molecules |
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Saprophytes |
- live on dead organic matter |
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Parasites |
- derive nutrients from a living host |
