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Bio Chapter 6
| Question | Answer |
|---|---|
| If cells cannot respire, will run out of carriers available to accept electrons Glycolysis will stop | Fermentation |
| uses pyruvate or derivative as terminal electron acceptor to regenerate NAD+ Glycolysis can continue | Fermentation |
| Also breaks down glucose Important in biosynthesis of precursor metabolites Ribose 5-phosphate, erythrose 4-phosphate Also generates reducing power: NADPH Yields vary depending upon alternative taken | Pentose Phosphate Pathway |
| The oxidation of glucose to pyruvic acid, produces ATP and NADH. | Glycolysis |
| Converts 1 glucose to 2 pyruvates; yields net 2 ATP, 2 NADH | Glycolysis |
| 2 phosphate groups added Glucose split to two 3-carbon molecules | Investment Phase |
| 3-carbon molecules converted to pyruvate Generates 4 ATP, 2 NADH total | Pay-off Phase |
| Completes oxidation of glucose | Tricarboxylic Acid (TCA) Cycle |
| CO2 is removed from pyruvate Electrons reduce NAD+ to NADH + H+ 2-carbon acetyl group joined to coenzyme A to form acetyl-CoA | Transition Step |
| What Produces... 2 CO2 2 ATP 6 NADH 2 FADH2 Precursor metabolites | TCA cycle |
| Reducing power: 2 NADH + 2 H+. Precursor metabolites: One precursor metabolite (acetyl-CoA). | Transition step yields |
| Completes oxidation of glucose | TCA Cycle |
| 2 CO2 2 ATP 6 NADH 2 FADH2 Precursor metabolites | TCA produces |
| The TCA cycle begins when CoA transfers its acetyl group to the 4-carbon compound oxaloacetate, forming the 6-carbon compound citrate. "The acetyl group is transferred to oxaloacetate to start a new round of the cycle." | TCA step 1 |
| Citrate is then chemically rearranged to make isocitrate. "Chem rearrangement occurs" | TCA Step 2 |
| this is oxidized and a molecule of CO2 removed, producing the 5-carbon compound α-ketoglutarate. During the oxidation, NAD+ is reduced to NADH + H+ "redox reaction generates NADH and CO2 is removed." | TCA step 3 |
| α-ketoglutarate is oxidized, CO2 is removed, and CoA is added, producing the 4-carbon compound succinyl-CoA. During the process, NAD+ is reduced to NADH + H+ "A redox reaction generates NADH,CO2 is removed,and coenzyme A is added" | TCA step 4 |
| The energy released during CoA removal is harvested to produce ATP. | TCA Step 5 |
| A redox reaction generates FADH2- | TCA Step 6 |
| Water is added | TCA Step 7 |
| A redox reaction generates NADH | TCA Step 8 |
| ATP: 2 ATP produced in step 5. Reducing power: Redox reactions at steps 3, 4, 6, and 8 produce a total of 6 NADH + 6 H+ and 2 FADH2. Precursor metabolites: Two intermediates of the TCA cycle, formed in steps 3 and 8, are precursor metabolites. | TCA cycle yields |
| Uses reducing power (NADH, FADH2) generated by glycolysis, transition step, and TCA cycle to synthesize ATP | Cellular respiration |
| Electron transport chain generates proton motive force Drives synthesis of ATP by ATP synthase | Cellular respiration |
| membrane-embedded electron carriers; it accepts electrons and then passes those electrons from one carrier to the next. The transfer of electrons can be likened to a ball falling down a set of stairs; energy is released as the electrons are passed | Electron Transport chain |
| The energy released allows the ETC to pump protons across the membrane, generating the electrochemical gradient called _____ | Proton motive force |
| in cytoplasmic membrane | ETC Prokaryotes |
| in inner mitochondrial membrane | ETC Eukaryotes |
| Three carriers general groups are notable | Quinones,Cytochromes, Flavoproteins |
| Lipid-soluble molecules Move freely, can transfer electrons between complexes | Quinones |
| Contain heme, molecule with iron atom at center Several types | Cytochromes |
| Proteins to which a flavin chemical group is attached FAD, other flavins synthesized from riboflavin | Flavoproteins |
| Accepts electrons from NADH, transfers to ubiquinone Pumps 4 protons | Complex I (NADH dehydrogenase complex) |
| Accepts electrons from TCA cycle via FADH2, “downstream” of those carried by NADH Transfers electrons to ubiquinone | Complex II (succinate dehydrogenase complex) |
| Accepts electrons from ubiquinone from Complex I or II 4 protons pumped; electrons transferred to cytochrome c | Complex III (cytochrome bc1 complex) |
| Accepts electrons from cytochrome c, pumps 2 protons Terminal oxidoreductase, meaning transfers electrons to terminal electron acceptor (O2) | Complex IV (cytochrome c oxidase complex) |
| even single species can have several alternate carriers E. coli serves as example of versatility of prokaryotes | Variation of ET componets of prokaryotes |
| This bacterium uses aerobic respiration when O2 is available, but in the absence of O2 it can switch to anaerobic respiration if a suitable electron acceptor such as nitrate is present. | E.coli variation |
| Can use 2 different NADH dehydrogenases Can produce several alternatives to optimally use different energy sources, including H2 Lack equivalents of complex III or cytochrome c Different components for high and low oxygen environments | E.coli Aerobic respiration |
| Harvests less energy than aerobic respiration-Lower electron affinities of terminal electron acceptors Some components different Nitrate (NO3 -)as terminal electron acceptor Produces nitrite (NO2 -) E. coli converts to less toxic ammonia (NH3) | Anaerobic respiration in E.coli |
| Harvesting the Proton Motive Force to Synthesize ATP | ATP Synthase |
| Energy required to establish gradient is ______ when gradient is eased | Released |
| ATP synthase allows protons to flow down gradient in controlled manner | Uses energy to add phosphate group to ADP 1 ATP formed from entry of ~3 protons |
| used when respiration not an option | Fermentation |
| E. coli is a ______ able to use any of three ATP-generating options: aerobic respiration, anaerobic respiration, and fermentation. | Faculatative anaerobe |
| Streptococcus pneumoniae lacks ______ so Fermentation only option | Electron transport chain |
| ATP-generating reactions are only those of | Glycolysis |
| Fermentation end products varied; helpful in identification, commercially useful | Ethanol Butyric acid Propionic acid 2,3-Butanediol Mixed acids |
| ____ can use variety of compounds other than glucose | Microbes |
| To break these down into their respective sugar, amino acid, and lipid subunits, cells synthesize | Hydrolytic enzymes which break down bonds by adding water |
| Excrete hydrolytic enzymes; transport subunits into cell and then... | Degrade further to appropriate precursor metabolites |
| Amylases digest starch; cellulases digest cellulose Disaccharides hydrolyzed by specific disaccharidases | Polysaccharides and disaccharides |
| Fats hydrolyzed by lipases; glycerol converted to dihydroxyacetone phosphate, enters glycolysis Fatty acids degraded by β-oxidation to enter TCA cycle | Lipids |
| Hydrolyzed by proteases; amino group deaminated Carbon skeletons converted into precursor molecules | Proteins |
| Anaerobic production of energy producing either alcohol or acid | What is fermnentation? |
| Synthesize new parts Cell walls, membranes, ribosomes, nucleic acids Harvest energy to power reactions | Cells need to accomplish two fundamental tasks |
| All the chemistry in the cell | Metabolism |
| Can separate metabolism into two parts | Catabolism and Anabolism |
| Processes that degrade compounds to release energy Cells capture to make ATP | Catabolism |
| Biosynthetic processes Assemble subunits of macromolecules Use ATP to drive reactions | Anabolism |
| Potential: stored energy (e.g., chemical bonds, rock on hill, water behind dam) Kinetic: energy of movement (e.g., moving water) | Two types of energy |
| Photosynthetic organisms harvest energy in _____ | sunlight |
| Power synthesis of organic compounds from CO2 Convert kinetic energy of photons to potential energy of chemical bonds | Photosynthetic organsims |
| ______ obtain energy from organic compounds Depend on activities of photosynthetic organisms | Chemoganotrophs |
| Biological catalysts: accelerate conversion of substrate into product by lowering activation energy Highly specific: one at each step Reactions would occur without, but extremely slowly | Role of enzymes |
| _____ can be denatured by temperature, salt concentration and pH | Enzymes |
| Enzyme activity controlled by binding to ______ site | allosteric |
| Distorts enzyme shape, prevents or enhances binding Regulatory molecule is usually end product Allows feedback inhibition | Allosteric regulation |
| ______ binds to active site of enzyme Chemical structure usually similar to substrate Concentration dependent; blocks substrate Example is sulfa drugs blocking folic acid synthesis | Competitive inhibitor |
| _____ binds to a different site Allosteric inhibitors are one example; action is reversible Some non-competitive inhibitors are not reversible | Non-competitive inhibitor |
| Substrate-level phosphorylation, oxidative phosphorylation, photophosphorylation | Thrree process generate atp |
| Exergonic reaction powers | Substrate-level phosphorylation |
| Proton motive force drives | oxidative phosphorylation |
| Sunlight used to create proton motive force to drive | photophosphorylation |
| The mechanism____ involves 2 processes. 1st the electron transport chain uses the reducing power of NADH and FADH2 to generate a proton motive force. 2nd the enzyme ATP synthase uses the energy of the proton motive force to drive the synthesis of ATP. | oxidative phosphorylation |
Created by:
cshelly