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U-M BIOLOGY 172 - Metabolism and Cell Respiration
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NucleusMost bacteria10 m1 m0.1 m1 cm1 mm100 µm10 µm1 µm100 nm10 nm1 nm0.1 nmHuman heightLength of somenerve and muscle cellsChicken eggFrog eggMost plant andanimal cellsMitochondrionSmallest bacteriaVirusesRibosomesProteinsLipidsSmall moleculesAtomsUnaided eyeLight microscopeElectron microscopenucleusMost bacteriaBIO 172 1st Edition Lecture 13Outline of Last Lecture I. Cell StructureII. Extracellular MembraneIII. Cell CommunicationOutline of Current Lecture I. MicroscopyII. MetabolismIII. Cellular RespirationCurrent LectureUnderstand cells by looking at them: Microscopy.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Fluorescence Microscopy helps you see and identify organelles within a cell:Scanning Electron Microscopy:the specimen is coated with a thin film; usually gold electron beam scans back and forth across the specimen. Allows for surface visualization.Transmission Electron Microscopy: High Resolution! But a cell specimen must already be thinly sectioned, which is hard to do, to obtain an image.Metabolic Lifestyles:the carbon source helps build macromolecules. Autotrophs use CO2 because it can be fixed by them.Photoautotroph: Energy source is Light. Carbon source is CO2. Examples: Plants, Algae, and CyanobacteriaChemoautotroph: Energy source is Inorganic or chemical compounds. Carbon source is CO2.Examples: Certain Prokaryotes.Photoheterotroph: Energy source is light. Carbon source is Organic compounds.Examples: Some marine prokaryotes.Chemoheterotrophs: Energy source is organic or chemical compounds. Carbon source is organic compounds.Examples: many prokaryotes, protists, fungi, and animals.Q: an organism that does not grow from glucose, or in the dark, is what?A: a photoautotroph!What is metabolism? Glucose carries energy in the form of its bonds. When bonds are extracted, they are used as an energy source for the cell.Similarly, ATP holds energy in its phosphate bonds. When broken, those bonds allow certain reactions to take place. ATP has a lot of Free Energy!NADH carries electrons, ends up dumping them into the Electron Transport Chain.FADH2 carries electrons, and dumps them into the Electron Transport Chain.+ Phosphate bonds store energy. Breaking of bonds allows energy to be released. Allows many proteins to bond and enzymes can use this.For example: Helicase unwinding DNA uses ATP as energy source. ATP is the major energy-carrying molecule through cellular pathways.When ATP is hydrolyzed, or goes through a chemical reaction with water . . .ATP + water + release of 7.3 k/cals per mol. Hydrolysis of ATP is exergonic.ADP built back up to ATP needs a net input of energy to get that done. Endergonic.But in order for this reaction to even occur, a substrate must make the net energy release be negative, so exergonic, because otherwise ADP could never turn back into ATP on its own.Key Energy Carrying Molecules (Electron Carriers)NAD+ is an electron acceptor. It takes electrons and carries them to other areas of the cell. Taking electrons to the site of Oxygen Phosphorylation is the NAD’s major function!FAD carries and donates electrons to Complex II of the ETC.NADP+ carries electrons, donates them to the Calvin Cycle to reduce carbon compounds during carbohydrate synthesis. (Reducing a compound means adding an electron to it)NADH is what stores the energy for later synthesis of ATP.In order for an Endergonic Reaction to occur . . . ATP must provide energy!ATP is required for other functions in the cell. ACTIN and MYOSIN require ATP to pull their vacuole along. ATP helps hydrolyze and allow the movement of ACTIN and MYOSIN.Metabolism:Glucose is central to metabolism in heterotrophs. Glucose or Fatty Acids are broken down into forms of energy the cell can use (like ATP or NAD+).Starch/glycogen with many glucose monomers linked together. Breaking down glucose helps give energy to the cell.Fermentation: generate ATP in absence of Oxygen.Respiration: oxygen as terminal electron acceptor.Extracting energy from Glucose: Carbohydrate: go through catabolism to break it down and take the sugars so they can be oxidized. Their electrons are taken out, and ATP generated through this process. Substrate level phosphorylation makes some ATP. Then Anabolism is what regenerates the energy-containing molecule.Only the electron (e-) on the outer most shell can be extracted. Nonpolar bonds are farther from nucleus. Because they are even between two nuclei. (Closer to nucleus is more polar and has lower potential energy). Thus we want to get the electrons… and then the nonpolar covalent bonds have electrons that are easier to access!The best sources of electrons, and therefore the best sources of energy, are C-H and C-C bonds!What is a Redox Reaction?Redox: Reduction-Oxidation reactions involve electron transfer. Redox reactions drive ATP formation. When an atom or molecule gains an electron, it is REDUCED. When an atom or molecule loses an electron, it is OXIDIZED.A redox reaction is always coupled. This process generates energy, because an electron donor is coupled with an electron acceptor.ADPEnzymePhosphorylatedsubstrateATPA way to remember what happens for Oxidation/Reduction: LEO says GER.Loses Electrons OXIDATION. Gains Electrons REDUCTION.Xe- + Y à X + Ye- so X is being oxidized, and Y is being reduced.Rearranging or transferring electrons during chemical reactions releases OR requires (uses) energy. By moving an electron to a more electronegative atom (like oxygen) releases energy.For example: CH4 has electrons equally shared.When it’s converted to Co2, the Electrons are not equally shared. They are spread out differently. Carbon was Oxidized (because electrons move farther away from its nucleus!)Oxygen becomes reduced because it gains electrons.The steps for Extracting Energy from Glucose:1. Glycolysis. A little ATP is produced, and NADH. Glycolysis uses some ATP too. Pyruvate is a product, and pyruvate is what gets put into the citric acid cycle.2. Citric Acid Cycle. A little ATP and NADH are produced again.3. Electron Transport Chain. Uses NADH to make a lot of ATP!The oxidization of Glucose (and other fuel molecules) is what generates useful energy.Substrate level phosphorylation (krebs cycle=citric acid cycle) happens within the mitochondria matrix.Oxidative phosphorylation: happens in ETC, within the inner mitochondrial


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U-M BIOLOGY 172 - Metabolism and Cell Respiration

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