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Dr. Cop's Chapter 7
| Question | Answer |
|---|---|
| Metabolism: | the sum total of the chemical reactions in an organism or cell. |
| Catabolism: | degradative or breakdown reactions; release energy (exergonic); ex: hydrolysis. |
| Anabolism: | biosynthetic or buildup reactions; require energy input (endergonic); ex: dehydration synthesis. |
| Energy: | the capacity to do work: life can't create or destroy it; organisms convert it form one form to another. |
| Covalent bonds represent a bit of trapped energy. As a result, energy will be given will be given off when | covalent bonds are broken and , it will require input of energy to make covalent bonds. |
| Metabolic activities are never 100% efficient; there is always some | wasted energy, usually in the form of heat. |
| A metabolic pathway is a | sequence of enzymatically catalyzed chemical reactions in a cell |
| In a metabolic pathway, the products of one reaction are the | reactants for the next reaction, etc. |
| Metabolic pathways are determined by | enzymes; each reaction will have a specific enzyme |
| Enzymes are encoded by | genes (most are proteins). |
| Enzymes are | Biological catalysts, are specific, and can act fast. |
| Biological catalysts are | specific for a chemical reaction; not used up in that reatcion - makes them efficient. |
| Most enzymes are | proteins. |
| Ribozymes are | RNA molecules with enzymatic activity; some require a cofactor |
| Aponenzyme is | a protein |
| Cofactor: | Nonprotein component. |
| Coenzyme: | organic cofactor |
| Holoenzyme: | Aponezyme plus cofactor |
| Enzyme inhibitors | blocks substrate binding to active site; competitive inhibition. |
| Allosteric inhibition | noncompetitive inhibition. |
| Oxidation | Adds oxygen, removes elections, and removes hydrogen. |
| Reduction | Removes oxygen, adds electrons, and adds hydrogen. |
| "Redux" | reaction is the simultaneous oxidation of one substance and reduction of another. |
| Oxidation reduces | energy content. |
| Reduction increases | energy content. |
| Microbes are more | metabolically diverse than eukaryotes. |
| Any organism will require a | carbon sourse and an energy source. |
| Many anabolic or biosynthetic pathways are similar; more diversity exists in | the reactions used by microbes to acquire the energy that they need. |
| Energy metabolism in heterotrophs involves: | catabolism. |
| Microbes are divided into categories based on their | preferred carbon source and their preffered energy source. |
| Microbes are divided into these four basic nutritional categories: | Chemoheterotrophs, Chemoautotrophs, Photoheterotrophs, and Photoautotrophs. |
| Chemoheterotrophs('hetero' means 'other'): | Energy source: oxidize organic chemical compounds; carbon source: organic compounds; most microbes fall into this category |
| Chemoautotrophs ('auto' means 'self'): | Energy source: oxidize inorganic chemical compounds; carbon source: Co2; only some bacteria and archaea are in this category. |
| Photoautotrophs: | Energy source: light; carbon source: CO2; includes only bacteria and those eucaryotes that contain chloroplasts. |
| Photoheterotrophs: | Energy source: light; carbon source: organic compounds; some bacteria and some algae are in this category. |
| Microbial metabolism is also categorized on the basis of its | relationship to oxygen. |
| Aerobes: | organisms that have adapted to growth in the presence of air (which is about 20% oxygen). |
| Anaerobes: | organisms that have no protective mechanisms against the toxic effects of oxygen; live in habitats from wich oxygen is excluded. |
| Metabolism of aerobes: | oxygenic, photosynthesis, anoxygenic, and photosynthesis. |
| Metabolism of anaerobes: | Fermentation, anaerobic respiration, anoxygenic, and phothsynthesis. |
| Many microbes can switch from one category to another, depending on the conditions. Many chemoheterotrophs use | aerobic respiration when oxygen is present and fermentation (or anaerobic respiration) when it is absent or aerobically as chemoheterotrophes using aerobic respiration |
| Bacteria can grow | anerobically in the light, using anoxygenic photosynthesis, or aerobically as chemoheterotrophs using aerobic respiration. |
| The term facultative is used to | designate organisms that can use two or more modes of metabolism ("take it or leave it"). |
| The opposite of facultative is | obligate ("have to"). |
| Centeral metabolism: | interconverts a small number of small organic compounds needed for biosynthesis; many of same reactions used in energy metabolism as well; such pathways are called amphibolic. |
| The pathways of centeral metabolism, biosynthesis, and macromolecule assembly are | nearly identical in all organisms. |
| The commonality of central metabolism, biosynthesis, and macromolecule assembly, often termed unity of biochemistry, is | powerful evidence for the descent of all life on earth from a single common ancestor. |
| Oxoglutarate dehydrogenase is found principally in | aerobic chemoheterotrophs; allows them to have a complete Krebs cycle. |
| Chemoheterotrophs normally use the same organic compound for | both biosysthesis and respiration; ex: glucose. |
| Macromolecules are hydrolyzed by | extracellular enzymes. |
| The first step in the degradation of most organic matter is | hydrolysis to monomers. |
| Eucaryotic microbes do this within phagolysosomes during intracellular digestion: | the monomers are taken into the cytosol by permeases in the phagolysosome membrane. |
| Procaryotes hydrolyze macromolecules by secreting | extracellular hydrolases; the monomers are taken up by active transport. |
| Most solute uptake by procaryotes is by | active transport. |
| The procaryote's low-nutrient environments force them to use | active transport by high-affinity prmeases to concentrate the compounds they take up. |
| The use of permeases maintains | habitats so deficient in nutrients. |
| In most habitats, nearly all of the available soluble nutrients have been assimilated into | microbial cells or oxidizzed to CO2 (very competitive environments). |
| In many bacteria, sugar uptake is by a | phosphotransferase system. |
| Adding phosphorus to something: | changes it. |
| Cells interconvert two forms of energy: | an ionic potential and high energy compounds like ATP. |
| Ionic potential refers to a significant concentration gradient for an ion between | two locations (often H+ and often across a membrane); movement of the ions is a useable form of energy. |
| All cells need chemical energy in the form of | ATP, GTP, UTP, PEP (phosphoenolpyruvate), and some others. |
| ATP is used in most energy-requiring reactions of | biosynthesis. |
| GTP and UTP are frequently used in | macromolecular assembly reactions. |
| PEP is used in | many transport reactions. |
| Prokaryotes will demonstrate greater diversity in forms of | energy used. |
| The chemiosmotic potential that releases energy during ionic movement is due to | the exterior of the cell being more acidic and more positively charged relative to the interior fo the cell. |
| A chemiosmotic potential can be made in two ways: | Interconversion of membrane potential and chemical energy. |
| How do cells generate ATP | Substrate level phosphorylation, oxidative phosphorylation, and photophosphorylation. (part of photosynthesis). |
| Phosphorylation refers to | adding a phosphate ion to another compound; commonly adding phosphate to ADP to make ATP again. |
| Energy catabolism is | converting covalent chemical bond energy into usable from - like ATP. |
| Energy catabolism is the breaking down (primarily by oxidation) of "food fuels" to | simpler compounds, releasing energy. |
| "Food fuels" are | compounds that contain calories (a unit for measuring energy); includes carbs, lipids, and proteins; usually begin with carbs since glucose is common energy source usable by most organisms. |
| The breakdown of carbohydrates to release energy may involve three metabolic pathways: | Glycolysis, Kreb's cycle, and electron transport chain. |
| Glycolysis | the oxidation of glucose to pyruvic acid produces ATP and NADH2. |
| Glycolysis acts in these ways | - in cytoplasm- 10 reactions -to lop off the glucose half- specific enzyme for each - rxns are fast & easy- anaerobic- 'old' pathway- products are: 2 pyruvic acid 2 ATP (net) 2 NADH2 |
| Although it is an oxidation, glycolysis does not use | oxygen (is anaerobic). |
| Fermentation is a mode of | chemotrophic energy metabolism in which most or all of the ATP is made by substrate-level phosphorylation. |
| Last action of fermentation is substreate action of | phosphorolation. |
| Fermentation produces end products at the | same average redox level as the substrates. |
| Some fermentations do not involve | redox reactions. |
| The chemistry is such that a substrate-level phosphorylation can occur without | any oxidation of the organic substrate. |
| Many different kinds of compounds can be fermented - commonly involves | carbs, especially sugars; amino acids also can be fermented and other organic compounds. |
| Sugars might derive from polysaccharides like | starch and amino acids from protien breakdown. |
| Individual microbes are generally limited in their fermentation capabiity but, recall that pure cultures do not occur in nature - mixed cultures do, so overall a mixture of fermenting organisms can result in | substantial breakdown of biomass. |
| Alternatives to glycolysis - Pentose phosphate pathway / shunt: | uses pentoses and NADPH2, supplies ribose and deoxyribose, supplies reduced NADP needed for lipid synthesis, and operates with glycolysis. |
| Respiration is a type of chemotrophic energy metabolism isn which most or all of the ATP is made by | chemiosmotic means. |
| In aerobic respiration, oxygen is used as food fuels are completely oxidized to | carbon dioxide and water. |
| Many covalent bonds are broken in aerobic respiration so much energy is | released. |
| Some of theis energy is 'trapped' in the | ATP molecule. |
| Glycolysis is the first pathway in | aerobic repiration. |
| The 'additional rxns' of fermentation are not done, instead | pyruvic acid enters the Kreb's cycle. |
| Reactions of the electron transport chain (ETC) will | complete the process. |
| Most oxidations of woganic compounds reduce | NAD+. |
| Every oxidation must be accompanied by a | simultaneous reduction. |
| Electrons removed from one compound (oxidation) must be | added to another (reduction). |
| Most of the soluble oxidation reaction of metabolism use the same | electron acceptor: NAD |
| Some reduced NAD was produced in glycolysis but much more will be produced in the | next pathway - the Kreb's cycle. |
| In eukaryotes, the Kreb's cycle takes place in the | matrix of the mitochondria (inside the inner membrane). |
| Kreb's cycle begins with the | pyruvic acid produced in glycolysis. |
| Pyruvic acid (from glycolysis is | oxidized and decarboyxlated. |
| Oxidation of acetyl CoA produces | NADH2 and FADH2. |
| Kreb's cycle is 8 reactions that to in a | circle; twice per glucose |
| In eukaryotes, takes place in | matrix of mitochondria. |
| The Electron transport chain | is a series of carrier molecules that are, in turn, reduced and then oxidized as electrons are passed down the chain. |
| Energy released can be used to produce ATP by | chemiosmosis. |
| In ETC, a series of carrier molecules generally are embedded in a membrane; in eukaryotes - the | inner membrane of the mitochondria (there is also an ETC in the thylakoid membranes in chloroplasts in photosynthetic eukaryotes). |
| ETC is blocked by | cyanide. |
| The electron transport system consists of | two or three separate complexes of protein. |
| Each of the proteins of the electron transport system has prosthetic groups that are | responsible for carrying the electrons. |
| The most common prosthetic groups are | hemes and iron-sulfur centers. |
| One or another quinone mediates transfer from the | dehydrogenase complex to the cytochrome b/c complex. |
| A small, soluble cytochrome normally mediates transfer of | electrons from the cytochrome b/c complex to the oxidase. |
| Pathway for eukaryote and prokaryote glycolysis | cytoplasm. |
| Pathway for eukaryote and prokaryote intermediate step | cytoplasm. |
| Pathway for Kreb's cycle in eukaryote | mitochondrial matrix |
| Pathway for Kreb's cycle in prokaryote | cytoplasm. |
| Pathway for ETC in eukaryote | mitochondrial inner membrane |
| Pathway for ETC in prokaryote | plasma membrane. |
| Total possible 38 ATP per | glucose. |
| Fermentation produced | 2 ATP per glucose. |
| Aerobic respiration is more | efficient. |
| Fermentation is only used by | some microbes (doesn't produce enough ATP to support a large, multicellular eukaryote. organism). |
| Aerobic respiration only traps 43% of | the bond energy from glucose in ATP - remainder is heat. |
| Some microbes can use something other than oxygen as the terminal electron acceptor; this is called | anaerobic respiration. |
| Alternate oxidases are used for different | electron acceptors. |
| Many prokaryotes are able to use | nitrate or nitrite in the absence of oxygen. |
| Nitrate respiration is when | the nitrate is reduced to the nitrite or ammonia. |
| When the nitrate is reduced to the gaseous end-product N2, the process is called | denitrification. |
| Dead fish smell is | trimethylamine. |
| NH3= | ammonia |
| Fatty acids are made by | adding 2-co 'units' together and they are broken down the same way (called beta oxidation). |
| Protein catabolism= | deamination, decarboxylation, dehydrogenation->organic acid,->Kreb's cycle. |
| 80-90% of alcohol is metabolized in the | liver. |
| Remainder of alcolol is excreted thru | the lungs, kidneys, and skin. |
| The average person can metabolize | 18g/hour. |
| 3 metabolic pathways can metabolize alcohol: | dehydrogenase (cytoplasm), MEOS (microsomal ethanol-oxidizing system)with H2O2 in proxisomes. |
| Acetaldehyde is toxic in | cells. |
| Acetaledhyde is changed to acetate in | the mitochondria. |
| MEOS also yeilds zero | free radicals. |
| When MEOS enzymes are increased, it often | alters metabolism of drugs, toxins, vitamins A&D, and carcinogens. |
| MEOS enzymes will first work on | alcohol - then will work on medications. |
| Alcoloh preferentially ties up | NAD (among other things, can decrease gluconeogenesis->hypoglycemia and increase uric acid (gout). |
| Inorganic= | non-carbon. |
| Chemoautotrophic respiration= | rock eaters |
| Chemoautotrophs oxidize | inorganic electorn donors for energy. |
| As autotrophs, they need a reductant for | CO2 fixation. |
| Chemoautotroph's inorganic electron donor has to do 2 things: | provide electrons fro energy-yeilding electron transport and provide electrons for CO2 reduction. |
| Oxidation of inorganic electron donors usually occurs in the | periplasm. |
| A majority of chemoautotrophic substrates are oxidized by enzymes in the perilasm that | pass electrons to quinone or cytochrome c. |
| Reverse electron transport is necessary for chemoautotrophs to generate | reductant. |
| Chemoautotrophic respiration is ver inefficient for 2 related reasons: | electrons enter the electron transport chain at the level of quinone or cytochrome c, few protons are pumped per pair of electrons, and much of the ^p is expended on generating reductant rather than ATP. |
| Anaerobic chemoautotrophic respirations commonly use H2 as | electron donor. |
| Methanogenesis pumps ions without a | cytochrome-based electron transport system. |
| Methanogenesis is the other major strictly | anaerobic chemoautotrophic respiration. |
| Methanogenesis is unique to the archaea and is the principal consumer of | hydrogen in anaerobic soils, fresh water sediments, and the animal intestinal tract. |
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