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68 Cards in this Set
- Front
- Back
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Metabolism
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All chemical reactions and physical workings of the cell
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Anabolism
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Usually requires energy
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Catabolism
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Usually releases energy
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Metabolism does:
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Assembles smaller molecules into larger macromolecules needed for the cell
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Metabolism does:
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Degrades macromolecules to produce starting material & energy
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Metabolism does:
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Energy is conserved in the form of ATP or heat
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Enzymes
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Catalyze the chemical reactions of life
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How enzymes work
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Energy of activation
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How enzymes work
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Physical site where substrates can be positioned
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Enzymes can be achieved by
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Increasing concentration of reactants
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Enzymes can be achieved by
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Increasing temperature
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Enzymes can be achieved by
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Adding a catalyst
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Enzyme structure
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mostly protein
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Types of enzymes
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Simple
Conjugated (holoenzymes) |
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Conjugated enzymes (holoenzymes) contain
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protein and nonprotein molecules
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Type of conjugated enzymes (holoenzymes)
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Apoenzyme
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Cofactors of enzymes
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either organic molecules (coenzymes) or inorganic elements (metal ions)
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Catalase
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Breaks down hydrogen peroxide
Requires Iron (Fe) |
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Oxidase
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Adds electrons to oxygen
Requires Iron (Fe) and Copper (Cu) |
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Hexokinase
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Transfers phosphate to glucose
Requires Magnesium (Mg) |
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Urease
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Splits urea into ammonium ion
Requires Nickel (Ni) |
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Nitrate Reductase
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Reduces nitrate to nitride
Requires Molybdenum (Mo) |
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Enzyme folding organization
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Primary, secondary, tertiary, and quaternary
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Enzyme folding sites
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Active site/catalytic
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Active Site & Specificity
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Substrate binds to active site; product is unstable due to steric hindrances
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Active Site & Specificity Models
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Lock and Key Model
Induced Fit Model |
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Enzyme-Substrate Interactions
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Temporary enzyme-substrate union must occur at the active site
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Enzyme-Substrate Interactions
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The bonds are weak and easily reversible
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Metallic cofactors include
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Fe, Cu, Mg, Mn, Zn, Co, Se
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Metallic cofactors functions
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activate enzymes
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Metallic cofactors functions
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bring the active site and substrate close together
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Metallic cofactors functions
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participate directly in chemical reactions with the enzyme-substrate complex
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Coenzymes
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Organic compounds that work in conjunction with an apoenzyme
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Coenzymes
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Removes a chemical group from one substrate molecule and adds it to another substrate
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Vitamins
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one of the most important coenzymes and/or coenzyme precursor
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Classification of Enzyme Functions
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Location of action
Type of action Substrate |
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Rate of Enzyme Production
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Enzymes are not produced in the cell in equal amounts or at equal rates
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Rate of Enzyme Production
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Constitutive enzymes
Regulated enzymes |
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Oxidation-reduction (redox) reactions
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A compound loses electrons, H (oxidized)
A compound receives electrons, H (reduced) |
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Common enzymes
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Aminotransferases
Phosphotransferases Methyltransferases |
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Microbial Enzymes in Disease
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Many pathogens secrete unique exoenzymes
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Microbial Enzymes in Disease
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Avoid host defenses or promote multiplication in tissues
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Microbial Enzymes in Disease
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Virulence factors or toxins
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diphtheria toxin
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ADP-ribosylation of EF-2
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tetanus toxin
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prevents inhibition of muscle contraction
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anthrax toxin
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Increase cAMP & induces apoptosis
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Enzyme Sensitivity influenced by
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temperature, pH, and osmotic pressure of an organism’s habitat
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Enzyme Sensitivity influenced by
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Denaturation
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Regulation of Enzymatic Activity and Metabolic Pathways
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Metabolic reactions usually occur in a multiseries step or pathway
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Regulation of Enzymatic Activity and Metabolic Pathways
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Each step is catalyzed by an enzyme
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Regulation of Enzymatic Activity and Metabolic Pathways
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Every pathway has one or more enzyme pacemakers
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Direct Controls on Enzyme Action
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Competitive Inhibition
Noncompetitive inhibition Negative feedback |
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Controls on Enzyme Synthesis
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Enzyme repression
Enzyme induction |
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Energy
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Exergonic reaction
Endergonic reaction |
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Biological Oxidation and Reduction
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Biological systems often extract energy through redox reactions
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Biological Oxidation and Reduction
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Redox reactions always occur in pairs (electron donor and electron acceptor)
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Biological Oxidation and Reduction
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The energy in the electron acceptor can be captured and stored in a high-energy molecule like ATP
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Electron Carriers
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repeatedly accept and release electrons and hydrogens
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Electron Carriers
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example: NAD
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Electron Carriers
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Facilitate the transfer of redox energy
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Electron Carriers
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Most carriers are coenzymes
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Adenosine Triphosphate (ATP)
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A temporary energy repository
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Adenosine Triphosphate (ATP)
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Three-part molecule
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Parts of Adenosine Triphosphate (ATP)
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Nitrogen base (adenine)
5-carbon sugar (ribose) Chain of three phosphate groups |
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The Metabolic Role of ATP
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Primary energy currency of the cell
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The Metabolic Role of ATP
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When used in a chemical reaction, must be replaced
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The Metabolic Role of ATP
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ADP + P = ATP requires energy
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ADP + P = ATP requires energy
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catabolic pathways in heterotrophs
substrate phosphorylation oxidative phosphorylation |
