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Microbio Ch 8
Metalbolism
52
Microbiology
Not Applicable
10/20/2016

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Term
Metabolism
Definition
All chemical and physical workings of a cell
Term
Catabolism
Definition
Degradative; breaks the bonds of larger molecules forming smaller molecules; releases energy
Term
Anabolism
Definition
Biosynthesis; process that forms larger macromolecules from smaller molecules; requires energy input
Term
Enzymes
Definition
Enzymes are biological catalysts that increase the rate of a chemical reaction by lowering the energy of activation (the resistance to a reaction); The enzyme is not permanently altered in the reaction; Enzyme promotes a reaction by serving as a physical site for specific substrate molecules to position
Term
Cofactors
Definition
Micronutrients; act as carriers to assist the enzyme in its activity; metal ions and vitamins
Term
Coenzymes
Definition
Micronutrients; vitamins only
Term
Exoenzymes
Definition
Transported extracellularly, where they break down large food molecules or harmful chemicals; examples are Cellulase, amylase, penicillinase
Term
Endoenzymes
Definition
Retained intracellularly and function there; Most enzymes are endoenzymes
Term
Constitutive Enzymes
Definition
Always present, always produced in equal amounts or at equal rates, regardless of the amount of substrate
Term
Regulated enzymes
Definition
Not constantly present; production is turned on (induced) or turned off (repressed) in response to changes in the substrate concentration
Term
Synthesis or Condensation Reactions
Definition
Anabolic reactions to form covalent bonds between smaller substrate molecules, require ATP, release one molecule of water for each bond formed
Term
Hydrolysis Reactions
Definition
Catabolic reactions that break down substrates into small molecules; requires the input of water to break bonds
Term
Sensitivity of Enzymes to Their Environment
Definition
Activity of an enzyme is influenced by the cell’s environment; Enzymes operate under temperature, pH, and osmotic pressure of organism’s habitat; When enzymes are subjected to changes in organism’s habitat they become unstable
Term
Labile
Definition
Chemically unstable enzymes
Term
Denaturation
Definition
Weak bonds that maintain the shape of the apoenzyme are broken
Term
Competitive Inhibition
Definition
Substance that resembles the normal substrate competes with the substrate for the active site
Term
Noncompetitive Inhibition
Definition
Enzymes are regulated by the binding of molecules other than the substrate away from the active site
Term
Enzyme repression
Definition
Inhibits at the genetic level by controlling synthesis of key enzymes
Term
Enzyme induction
Definition
Enzymes are made only when suitable substrates are present
Term
The Pursuit and Utilization of Energy
Definition
Energy: the capacity to do work or to cause change; Forms of energy include: Thermal, radiant, electrical, mechanical, atomic, and chemical
Term
Cell Energetics
Definition
Cells manage energy in the form of chemical reactions that make or break bonds and transfer electrons; Energy released is temporarily stored in high energy phosphate molecules. The energy of these molecules is used in endergonic cell reactions.
Term
Endergonic reactions
Definition
Consume energy
Term
Exergonic reactions
Definition
Release energy
Term
Redox reactions
Definition
Always occur in pairs; There is an electron donor which gets reduced and electron acceptor which gets oxidized then constitute a redox pair; Process salvages electrons and their energy; Released energy can be captured to phosphorylate ADP or another compound
Term
Electron and Proton Carriers
Definition
Repeatedly accept and release electrons and hydrogen to facilitate the transfer of redox energy; Most carriers are coenzymes: NAD, FAD, NADP, coenzyme A, and compounds of the respiratory chain
Term
Adenosine Triphosphate: ATP
Definition
Metabolic “currency”; Three part molecule consisting of: Adenine – a nitrogenous base, Ribose – a 5-carbon sugar, 3 phosphate groups; Removal of the terminal phosphate releases energy; ATP utilization and replenishment is a constant cycle in active cells
Term
Formation of ATP
Definition
Substrate-level phosphorylation; Oxidative phosphorylation; Photophosphorylation
Term
Substrate-level phosphorylation
Definition
Transfer of phosphate group from a phosphorylated compound (substrate) directly to ADP – occurs in all cells
Term
Oxidative phosphorylation
Definition
Series of redox reactions occurring during respiratory pathway
Term
Photophosphorylation
Definition
ATP is formed utilizing the energy of sunlight
Term
Metabolic Pathway
Definition
a sequence of chemical reactions where each reaction is catalyzed by a different enzyme. Initial reaction produces substrate for next enzyme – enzymes are regulated in a number of ways: Environmental factors and Feedback
Term
Bioenergetics
Definition
Study of the mechanisms of cellular energy release. Includes Anabolic and Catabolic Reactions.
Term
Metabolic Pathways
Definition
Nutrient processing is varied, yet in many cases is based on three catabolic pathways that convert glucose to CO2 and gives off energy
Term
Aerobic respiration
Definition
Glycolysis, the Kreb’s cycle,respiratory chain
Term
Anaerobic respiration
Definition
Glycolysis, the Kreb’s cycle, respiratory chain; molecular oxygen is not the final electron acceptor
Term
Fermentation
Definition
Glycolysis, organic compounds are the final electron acceptors
Term
Aerobic Respiration
Definition
Series or enzyme-catalyzed reactions in which electrons are transferred from fuel molecules (glucose) to oxygen as a final electron acceptor. Glycolysis – glucose (6C) is oxidized and split into 2 molecules of pyruvic acid (3C), NADH is generated. TCA – processes pyruvic acid and generates 3 CO2 molecules , NADH and FADH2 are generated. Electron transport chain – accepts electrons from NADH and FADH; generates energy through sequential redox reactions called oxidative phosphorylation
Term
Electron Transport and Oxidative Phosphorylation
Definition
Final processing of electrons and hydrogen and the major generator of ATP. Chain of redox carriers that receive electrons from reduced carriers (NADH and FADH2).
Term
Oxidative phosphorylation
Definition
ETS shuttles electrons down the chain, energy is released and subsequently captured and used by ATP synthase complexes to produce ATP
Term
Chemiosmosis
Definition
As the electron transport carriers shuttle electrons, they actively pump hydrogen ions (protons) across the membrane setting up a gradient of hydrogen ions – proton motive force. Hydrogen ions diffuse back through the ATP synthase complex causing it to rotate, causing a 3-D change resulting in the production of ATP
Term
The Terminal Step
Definition
Oxygen accepts 2 electrons from the ETS and then picks up 2 hydrogen ions from the solution to form a molecule of water. Oxygen is the final electron acceptor 2H+ + 2e- + ½O2 → H2O
Term
AEROBIC RESPIRATION SUMMARY
Definition
The energy yielding process in which: Initial electron donor is carbohydrate, the final electron acceptor is oxygen gas. The location of pathway: Eukaryotes: glycolysis – cytoplasm, CAC – mitochondria, ETC - mitochondria; Prokaryotes: glycolysis – cytoplasm, CAC – cytoplasm, ETC – cell membrane. Substrates include proteins, carbohydrates, lipids. C6H12O6 + 6O2 + 38 ADP + 38 P INTO 6CO2 + 6H2O + 38 ATP.
Term
Anaerobic Respiration
Definition
Functions like aerobic respiration except it utilizes oxygen containing ions, rather than free oxygen, as the final electron acceptor is Nitrate (NO3-) and nitrite (NO2-); Most obligate anaerobes use the H+ generated during glycolysis and the Kreb’s cycle to reduce some compound other than O2
Term
Fermentation
Definition
Incomplete oxidation of glucose or other carbohydrates in the absence of oxygen; Uses organic compounds as terminal electron acceptors; Yields a small amount of ATP; Production of ethyl alcohol by yeasts acting on glucose; Formation of acid, gas, and other products by the action of various bacteria on pyruvic acid
Term
Photosynthesis: The Earth’s Lifeline
Definition
The ultimate source of all the chemical energy in cells comes from the sun. The chemical formula - 6CO2 + 6H2O to produce C6H12O6 + 6O2
Term
Photosynthesis
Definition
Occurs in 2 stages: Light Dependent and Light Independent.
Term
Light-dependent
Definition
Photons are absorbed by chlorophyll, carotenoid, and phycobilin pigments; Water split by photolysis, releasing O2 gas and provides electrons to drive photophosphorylation; Released light energy used to synthesize ATP and NADPH
Term
Light-independent Reaction
Definition
Dark reactions go into the Calvin Cycle; Uses ATP to fix CO2 to ribulose-1,5-bisphosphate and convert it to glucose
Term
Photosynthesis
Definition
Metabolic process converting light energy to chemical energy and stored as carbohydrates or other organic compounds
Term
Classical Photosynthesis
Definition
Performed by PHOTOAUTOTROPHS: – plants, algae and Cyanobacteria. The initial electron donor is CO2, the final electron acceptor is water (H2O). The Products are O2 gas, H2O and Carbohydrates. There is NO net production of ATP
Term
Classical Photosynthesis
Definition
Consists of 2 sets of reactions: 1.Energy-fixing reactions (sunlight) 2.Carbon-fixing reactions (CO2) Net result is 6CO2 + 6H2O + light INTO C6H12O6 + 6O2.
Term
Bacterial Photosynthesis
Definition
Two different processes: 1. Photoautotrophs – Green & Purple Sulfur Bacteria – never produce oxygen gas. – Initial electron donor – CO2 – Final electron acceptor - H2S – Products: carbohydrates, H2O, sulfur (Sº) – Bacteriochlorophyll – primary photosynthetic pigment. The chemical formula is CO2 + 2H2S + light C6H12O6 + 2S + H2O. 2. Photoheterotrophs - Green & Purple Non-sulfur Bacteria – Initial electron donor - CO2 – Final electron acceptor – organic acids & alcohols – Products: carbohydrates, oxidized organic acids & alcohols – Bacteriochlorophyll – primary pigment CO2 + org acid + light INTO C6H1206 + oxidized org acids.
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