Chapter 6 – Microbiology – Flashcards

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Metabolism
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The sum of all biochemical processes taking place in a living cell
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Anabolism
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An energy-requiring process involving the synthesis of larger organic compounds from smaller ones
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Catabolism
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an energy-liberating process in which larger organic compounds are broken down into smaller ones
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Endergonic Reaction
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A chemical process that requires energy
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Exergonic Reaction
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A chemical process releasing energy
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Metabolic Processes
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occur in the cell cytosol, on the cell (plasma) membrane, in the periplasmic space (gram-negative bacteria), in eukaryotic organelles, and outside the cell
• cells need a large variety of enzymes
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Enzyme
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A reusable protein molecule that brings about a chemical change while itself remaining unchanged
? increase the probability of chemical reactions while remaining unchanged
? accomplish in fractions of a second what otherwise might take hours, days, or longer to happen spontaneously under normal biological conditions
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1. Enzymes are reusable
? once a chemical reaction has occurred, the enzyme is released to participate in another identical reaction

1. Enzymes
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1. are reusable
? once a chemical reaction has occurred, they are released to participate in another identical reaction
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2. Enzyme
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they are highly specific
? it functions in one type of chemical reaction usually will not participate in another type of reaction
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3. Enzymes
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3. They have an active site
? each has a special pocket or cleft called an active site which has a specific 3D shape complementary to a reactant called a substrate. The active site positions the substrate such that it is highly likely a chemical reaction will occur to form one or more products
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Active Site
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the region of an enzyme where the substrate binds
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Substrate
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The structure or substances upon which an enzyme acts
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Products
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A substance or substances resulting from a chemical reaction
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4. Enzymes
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They are required in minute amounts
? because it can be use thousands of times to catalyze the same reaction, only minute amounts of a particular ones are needed to ensure that a fast and efficient metabolic effect occurs
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Enzyme-Substrate Complex
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The association of an enzyme with its substrate at the active site
? chemical bonds in the substrate are stretched or weakened by the enzyme, causing the bond to break. Are forced to overlap in the spot where the chemical bond will form
? in this complex, the electrons shells
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Activation Energy
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the energy that is required for a chemical reaction to occur
? the enzymes create an alternate pathway of less resistance and a lower activation energy barrier; they destabilize the chemical bonds and form new ones by separating or joining atoms in a carefully orchestrated fashion
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Lysozome
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An enzyme found in tears and saliva that digests the peptidoglycan of gram-positive bacteria cell walls
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Cofactor
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An inorganic substance that acts with and is essential to the activity of an enzyme (e.g. include metal ions [ Mg2+, Fe2+, Zn2+] and some vitamins)
? participate in catalytic reactions,
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Coenzyme
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A small, organic molecule that forms the nonprotein part of an enzyme molecule
? e.g. nicotinamide adenine dinucleotide (NAD+) and Flavin Adenine Dinucleotide (FAD) [ play significant role as electron carriers in metabolism]
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Metabolic Pathway
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a sequence of linked enzyme-catalyzed reactions in a cell
? each reaction catalyzed by a different enzyme, in which the product (output) of one reaction serves as a substrate (input) for the next reaction
? starts with the initial substrate and finished with the final end product; products of “in-between” stages are called “intermediates”
? can be anabolic, where larger molecules are synthesized from smaller monomer
? other pathways are catabolic because they break larger molecules into smaller ones
? can be linear, branched, or cyclic
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Enzyme Inhibition by Environmental Factors
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? enzymes are sensitive to temperature changes (high temperature = denaturation of protein enzyme)
? increase or decrease in protons (H+) will interfere with reaction rate, extreme changes can lead to denaturation or enzyme and metabolic inhibition
? chemicals applied to the environment like alcohols and phenol inactivate enzymes and precipitate proteins, making them natural disinfectants; or other natural chemicals interfere w/enzyme action (penicillin) or w/a cell’s ability to carry out a critical enzyme reaction (sulfa drugs) making them effective antibiotics
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Enzyme Inhibition by Metabolic Pathways
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- one of the most common ways of modulating enzyme activity is for the final end product of a metabolic pathway to inhibit an enzyme in that pathway
-if the first enzyme in the pathway is inhibited, then no product is available as input for the rest of the pathway
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Feedback Inhibition
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The slowing down or prevention of a metabolic pathway when excess end product binds noncompetitively to an enzyme in the pathway
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Noncompetitive Inhibition
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The prevention of a chemical reaction by a chemical that binds elsewhere than to active site of an enzyme
? when the final end product or any molecule binds to a non-active site on the enzyme, the shape of the active site changes and can no longer bind substrate
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Noncompetitive Inhibition
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The prevention of a chemical reaction by a chemical that binds elsewhere than to active site of an enzyme
? when the final end product or any molecule binds to a non-active site on the enzyme, the shape of the active site changes and can no longer bind substrate
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Competitive Inhibition
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the prevention of a chemical reaction by a chemical that competes with the normal substrate for an enzyme’s active site
? blocking its active site so the normal substrate cannot bind
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Adenosine Triphosphate (ATP)
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A molecule in cells that provides most of the energy for metabolism
? bacterial and archaeal cells it is formed on the cell membrane, while eukaryotes reactions primarily in the mitochondria
? provides energy for binary fission, flagellar motion, active transport, and spore formation
? chemical level, it fuels protein synthesis and carbohydrate breakdown
? cells need to have a continual supply of ATP and it cannot be stored
? relatively unstable because of the 3 phosphate groups packed tightly together
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Adenosine Diphosphate (ADP)
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A molecule in cells that is the product of ATP hydrolysis
? more stable
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Phosphorylation
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the addition of a phosphate group to a molecule
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ATP/ADP Cycle
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the cellular processes of synthesis and hydrolysis of ATP
? continuous cycle
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Mole
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the molecular weight of substance expressed in grams
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Calories
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unites of energy defined in the amount of heat required to raise one gram of water 1OC
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Cellular Respiration
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the process of converting chemical energy into cellular energy in the form of ATP
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Aerobic Respiration
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the process for transforming energy to ATP in which the final electron acceptor in the electron transport chain is the oxygen gas (O2)
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Anaerobic Respiration
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the production of ATP where the final electron acceptor is an inorganic molecule other than oxygen gas (O2) (e.g. nitrate and sulfate)
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Fermentation
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A metabolic pathway in which carbohydrates serve as electron donors, the final electron acceptor is not oxygen gas (O2) and NADH is reoxidized to NAD+ for reuse in glyocolysis for generation of ATP
-the catabolism of glucose starts with a little energy being converted to ATP, which builds to a point where large amounts of energy are converted to ATP, and the original glucose molecule has been depleted of its useful energy
-3 stages of energy extraction 1.) glyocolysis 2.) citric acid cycle 3.) oxidative phosphorylation
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Glycolysis
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A metabolic pathway in which glucose is broken down into two molecules of pyruvate with a net gain of two ATP molecules
? occurs in cytosol of all microorganisms and involves metabolic pathway that converts an initial 6-carbon substrate into two 3-carbon molecules.
? first part is endergonic ATP is hydrolyzed (consumed) in reaction 1 (produces glucose-6-phosphate and 3 produces fructose-1, 6-bisphosphate) the phosphate group from ATP attaches to the product
? exergonic: during reactions 7 and 10 ATP is generated, enough energy is release to synthesize an ATP molecule from ADP and phosphate, resulting in a total of 4 ATP molecules
? 1 and 3 the net gain from glycolysis is 2 molecules of ATP
? rxn 6 releases 2 high energy electrons and two protons (H+) which are picked up by the coenzyme NAD+ reducing it to NADH
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Glucose
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A six carbon sugar used as a major energy source for metabolism
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Pyruvate
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the end product of the glycolysis metabolic pathway
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Substrate Level Phosphorylation
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the formation of ATP resulting from the transfer of phosphate from a substrate to ADP
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Reducing (Reduction)
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referring to the process of a substance gaining electron pairs
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Citric Acid/Kreb's Cycle
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A metabolic pathway in which acetyl groups are completely oxidized to carbon dioxide gas and some ATP molecules are formed
? end product formed is used as one substrate to initiate the pathway
? all of the reactions are catalyzed by enzymes, and all take place along the cell membrane of bacterial and archaeal cells, including protozoa, algae, and fungi occur in mitochondria
? like a wheel constantly turning
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Coenzyme A (CoA)
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A small, organic molecule of cellular respiration that functions in release of carbon dioxide gas (CO2) and the transfer of electrons and protons to another coenzyme
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Acetyl CoA
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one of the starting compounds for the Krebs cycle
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Oxidation
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the process of removing electron pairs from a substance
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Oxidative Phosphorylation
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A series of sequential steps in which energy is released from electrons as they pass from coenzymes to cytochromes and ultimately to oxygen gas (O2) the energy is used to combine phosphate ions with ADP molecules to from ATP molecules
? responsible for producing 34 molecules of ATP per glucose; involves the NAD+ and FAD coenzymes that underwent reduction to NADH and FADH2 during glycosis and citric acid
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Cytochromes
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A compound containing protein and iron that plays a role as an electron carrier in cellular respiration and photosynthesis
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Electron Transport Chain
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A series of proteins that transfer electrons in cellular respiration to generate ATP
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Chemiosmosis
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the use of a proton gradient across a membrane to generate cellular energy in the form of ATP
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ATP Synthase
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the enzyme involved in forming ATP by using the energy in a proton gradient
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Deanimation
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a biochemical process in which amino groups are enzymatically removed from amino acids or other organic compounds
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Beta Oxidation
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The breakdown of fatty acids during cellular metabolism through the successive removal from one end of two carbon units
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Anaerobic Respiration
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relies on terminal, usually inorganic electron acceptors other than oxygen for ATP production
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anoxic
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without oxygen gas (O2)
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Fermentation
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enzymatic process for producing ATP using endogenous organic compounds as both electron donors and acceptors-exogenous electron acceptors (O2, NO3-, SO42-, CO3) are absent
? makes few ATP molecules in the absence of cellular respiration, but the citric acid cycle, and oxidative phosphorylation are shut down, so the products of glycolysis (pyruvate) are shuttled through a pathway that produces other final end products
? ensure a constant supply of NAD+ for glycolysis and the production of two ATP molecules per glucose
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Lactic Acid Fermentation
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A catabolic process that produces lactic acid during the reoxidation of NADH to NAD+ for reuse in glycolysis to generate ATP
? by S. lactis, the acid will curdle milk products
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Alcohol Fermentation
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A catabolic process that forms ethyl alcohol during the reoxidation of NADH to NAD+ for reuse in glycolysis to generate ATP
? C. albicans, controls carbohydrate to alcohol product
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Photosynthesis
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A biochemical process in which light energy is converted to chemical energy, which is then used for carbohydrate synthesis
? in eukaryotes, takes place in chloroplasts of organisms like diatoms, dinoflagelates, and green algae/ chlorophyll in bacteria
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Oxygenic Photosynthesis
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A form of photosynthesis in which molecular oxygen (O2) is produced
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Energy Fixing Reaction
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A reaction in the first part of photosynthesis where light energy is converted into chemical energy in the form of ATP
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Chlorophyll ?
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a magnesium-containing lipid soluble compound, a light energy is absorbed by the green pigment
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Photosystems
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A group of pigments that act as a light trapping system for photosynthesis
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Photophosphorylation
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the generation of ATP through the trapping of light
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Carbon Fixing Reactions
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A chemical reaction in the second part of photosynthesis in which carbohydrates are formed
? carbon dioxide is trapped into carbohydrates and other organic compounds
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Bacteriochlorophylls
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A pigment located in the membrane system of purple sulfur bacteria that upon excitement by light, loses electron and initiates photosynthetic reactions
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Anoxygenic Photosynthesis
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A form of photosynthesis in which molecular oxygen (O2) is not produced
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Autotrophs
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An organism that uses carbon dioxide (CO2) as a carbon source
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Photoautotrophs
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An organism that uses light energy to synthesize nutrients from carbon dioxide gas (CO2)
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Chemoautotroph
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An organism that derives energy from inorganic chemical and uses the energy to synthesize nutrients from carbon dioxide gas (CO2)
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Nitrogen Cycle
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A biogeochemical cycle that cycle nitrogen gas into nitrogenous compounds and back again
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Heterotrophs
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An organism that requires preformed organic matter for its energy and carbon needs
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Photoheterotrophs
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An organism that uses light energy to synthesize nutrients from organic carbon compounds
? like fatty acids and alcohols, include certain green nonsulfur and purple nonsulfur
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Chemohetertrophs
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An organism that derives energy from organic chemicals and uses the energy to synthesize nutrients from carbon compounds other than carbon dioxide gas (CO2)
? glucose
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Saprobes
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A type of heterotrophic organism that feeds on dead organic matter, like rotting wood or compost
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Pathogens
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A microorganism or virus that causes disease
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Parasites
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A type of heterotrophic organism that feeds on live organic matter like another organism
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Enzymes
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catalyze all cellular reactions, they are not changed by the reactions and can be reused, their activity is highly specific, and act on specific substrates, and are used in small quantities
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Enzyme-Substrate Complex
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Through this complex, enzymes increase the probability of a chemical reaction, and bind to the substrate at the active site, which is specific to the substrate
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Activation Energy
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Enzymes lower this so a reaction is more likely to occur, by weakening chemical bonds in the substrate
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Enzymes
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can be made entirely of proteins or contain a metal ion (cofactor) or an organic molecule (coenzyme)
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Metabolic Pathway
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a sequence of chemical reactions, each reaction is catalyzed by a different enzyme and the product of one reaction serves as the substrate for the next
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Metabolism
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regulated and be inhibited by enzymes
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Feedback inhibition
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hinders metabolic pathways by excess products inhibiting an enzyme in the pathway so no product is available to feed the next reaction
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Noncompetitive Inhibition
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changing the shape of the active site
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Competitive Inhibition
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blocking an active site
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ATP (adenosine triphosphate)
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Energy in this form is required for metabolism, because it is the cellular "energy currency" providing energy for movement, cell division, and protein synthesis
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Adensonsine diphosphate (ADP) and a free phosphate group
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What results when energy is released from ATP when the bond holding the last phosphate group on the molecule is broken?
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Phosphorylation
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adding a phosphate gorup to a molecule
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ATP cannot be stored because it is relatively unstable
Energy must be stored in more stable forms like glycogen and lipids
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What form of energy can be stored? what form of energy cannot be stored?
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Adenine, Ribose, 3 phosphate groups
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What is ATP composed of?
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Glucose
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contains stored energy that can be extracted, and released slowly by converting to ATP thorugh metabolic pathways
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Cellular Respiration
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a series of catabolic pathways for the production of ATP, which cells make ATP by harvesting energy through this process.
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Aerobic Respiration
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If oxygen is consumed while making ATP
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Anaerobic Respiration
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if oxygen is not consumed while making ATP
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oxygen
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required to create ATP during Aerobic Respiration
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Glycolysis
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is the splitting of 1-6Carbon glucose molecule into 2-3Carbon molecules, which requires 2 ATP molecules to start, but releases 4 ATP with a net gain of 2 ATP and 2 NADH molecules
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Citric Acid Cycle/Kreb's Cycle
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extracts more energy from pyruvate, constantly turning wheel that picks up pyruvate molecules from glycolysis and spitting out carbon dioxide, ATP, NADH, and FADH2
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Transition from gylcolysis to Kreb's
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enzymes remove a carbon from each pyruvate molecule, combines the carbon with coenzyme A (CoA) to form acetyl CoA releasing 2 NADH and 2 CO2
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2 ATP, 2 FADH2, 4 CO2, 6 NADH
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For each two pyruvate molecules that enter the Kreb's cycle, what molecules are formed?
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Oxidative Phosphorylation
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it makes the most ATP molecules, pairs of electrona re passed from one chemical to another, releasing energy, which is used to combine phosphate with ADP to form ATP, it is composed of electron carriers called cytochromes, and coenzyme carriers NADH, and FADH2 provide the electrons for this process
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Cytochromes
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electron carriers
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Chemiosmosis
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Electrons moves down the electron transport chain and pump protons out of the cell, the protons outside the membrane build up a concentration gradient
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ATP synthase
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A channel opens and the protons flow in through, which harnesses the energy from the flowing protons to phosphorylate ADP to ATP
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Oxygen
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Accepts the electron pair at the end of this process, acquires 2 protons, and becomes water
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Fats
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Chemical bonds that make up this molecule store large amounts of enegy making it good energy sources
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Saccharides
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What are other potential energy sources for prokaryotes?
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proteins
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When fats and carbohydrates are lacking cells use this?
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Deamination
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the replacement of the amino group in a protein with a carbonyl group in protein breakdown
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Beta Oxidation
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Fatty acids are broken down through this process
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Anaerobic Respiration
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produces ATP using other final electron acceptors (inorganic), anaerobes use moelcules rather than oxygen as the final electron receptor in the ETC, it produces less ATP than its alternative
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Fermentation
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produces ATP using an organic final electron receptor, it is used when oxygen and other alternative electron acceptors are unavailable
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Pyruvate
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can be converted to lactic acid to reform NAD+ coenzymes so glycolysis can produce ATP from glucose
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Eukaryotic Fermentation
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yeast used in alcoholic fermentation to create alcoholic beverages
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Photosynthesis
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a process to acquire chemical energy, light energy is converted to cehmical energy, which is stored as an organic compound
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Chloroplasts
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In eukaryotes, photosynthesis is carried out in these organelles
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Prokaryotic Photosynthesis
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photosynthesis is carried out in the cell membrane
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Chlorphyll ?
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the green pigment that absorbs light energy
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bacteriochlorophylls
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Some bacteria use this as other pigments
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Bacteriorhodopsin
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Some archaea use this as a pigment
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1.) Energy Fixing Reaction
2.) Carbon Fixing Reaction
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Photosynthesis is divided into two different sets of reactions
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Autotroph
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synthesize their own food from simple carbon sources like carbon dioxide
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Photoautotroph
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use light as their energy source
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Chemoautotroph
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use inorganic compounds as their energy source
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Heterotroph
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gain energy and carbon from outside sources
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Photoheterotrophs
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use light as their energy source and organic compounds as their source of carbon
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Chemoheterotrophs
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use organic compounds both for energy and carbon sources
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Saprobes
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feed exclusively on dead organic matter
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Parasite
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feed on living organic matter
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