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UM BIOM 250N - Energy in the Cell

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BIOM 250 1st Edition Lecture 6Outline of Last Lecture I. OrganellesII. Microbial MetabolismIII. Chemical ReactionsIV. EnzymesOutline of Current LectureI. Feedback InhibitionII. Energy in the CellIII. Oxidation-Reduction ReactionsIV. Oxidative PhosphorylationV. Carbohydrate CatabolismVI. Summary of RespirationCurrent LectureI. Feedback Inhibitiona. Enzymes usually function in pathwaysi. Enzymes are often required to complete an end productii. Pathway intermediates can go to other paths to form different productsb. Allosteric inhibitors can control enzyme functioni. Unused end-products often bind to the first enzyme in a pathwayii. When an enzyme is inhibited, no intermediates or final products formiii. This is called feedback or end-product inhibitioniv. This process is critical for control and efficient use of cell resourcesII. Energy in the Cella. Cell derives energy from the breaking of bondsb. Catabolic reactions can transfer energy from on molecule to anotherc. Usually an enzyme pathway harvests this energyd. Energy is available as ATP (adenosine triphosphate)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.III. Oxidation-Reduction Reactionsa. Oxidation- removal of electronsb. Reduction- gain of electronsc. Redox reaction- an oxidation reaction paired with a reduction reactiond. Usually electrons and protons are moved at the same timeIV. Oxidative Phosphorylationa. Energy released from the transfer of electrons (oxidation) from one compound toanother (reduction) is used to generate ATP in the electron transport chainb. The energy is used to place a phosphate group on an ADP molecule to form ATP—so this process is how ATP is formedV. Carbohydrate Catabolisma. The breakdown of carbohydrates to release energy follows three enzyme chains:i. Glycolysisii. Krebs Cycleiii. Electron Transport Chainb. Glycolysis process:i. Glucose is phosphorylated by a kinaseii. This splits it into two, three carbon molecules each with one phosphateiii. Each 3 carbon gives up electrons to NAD+ and gets another phosphateiv. Now the 3 carbons give up a phosphate to from 1 ATP for each carbon chainv. Rearrangements are made and 1 more ATP is formed by each carbon chainvi. The final product is pyruvatevii. Result- 2 ATP used, 4 ATP made, net gain of 2 ATPc. Krebs Cycle:i. Pyruvate is oxidized, NADH is formed and one carbon is releasedii. A two carbon acetyl group attaches to Coenzyme A (CoA)iii. CoA transfers two carbon to four carbon oxalic acid to form citric acid, which is a six carbon chainiv. Enzyme chain removes two carbons to form carbon dioxidev. Oxidation forms NADH and FADH2 vi. 1 ATP is formedvii. So—glucose is catabolized to carbon dioxide, electrons are on carriers NADH and FADH2, and ATP is formedd. The Electron Transport Chain:i. A series of carrier molecules are oxidized and reduced as electrons are passed down the chainii. Energy released is used to transfer protons from one side of the membrane to the otheriii. The proton gradient provides energy to form ATP for the cellVI. Summary of Respirationa. Aerobic Respiration- the final electron acceptor in the electron transport chain is molecular oxygen b. Anaerobic Respiration- the final electron acceptor in the electron transport chain is not molecular oxygeni. Yields less energy than aerobic respirationii. No terminal electron acceptor (nowhere for electrons to go after glucose is broken down)iii. Example: Yeast can use up all of the oxygen in its environment and then produce energy via


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