CHAPTER 12 PRACTICE PROBLEMS 1. K+ leak channels are found in the plasma membrane, and they gate open and closed inan unregulated, random manner. What do they get from a resting cell?They keep the electrochemical gradient for K+ at zero2. At the first step in glycolysis, what purpose is served by the phosphorylation of glucose to glucose 6-phosphate by the enzyme hexokinase?Helps drive the uptake of glucose from outside the cell3. What essential molecule regenerated by fermentation?NAD+4. What enzyme performs the first committed step in glycolysis?Phosphofructokinase5. If 3 ATPs are hydrolyzed by the Na+/K+ pump, how many Na+ and K+ ions move in/outof the cell?9 Na+ ions move out of the cell and 6 K+ ions move into the cell6. Using the molecules deoxyribose, methane, phosphate, and methanol, place these 4 molecules in order of least likely to most likely to diffuse across lipid bilayers.Phosphate<Deoxyribose<methanol<methane7. List the transport proteins that actively transport solutes.Na+/K+ ATPase, Antiporter, Symporter, and Light-driven pump8. Using the compounds Pyruvate, NADH, Acetyl-CoA, Glucose, and FADH2, order the compounds from lowest to highest, based on the total amount of energy a cell can harvest from the molecule during a complete aerobic metabolism.FADH2<NADH<Acetyl CoA<Pyruvate<Glucose9. What is the cellular (and subcellular, if relevant) location of Phosphofructokinase?Cytoplasm10. What is the cellular (and subcellular, if relevant) location of ATP synthase?Inner membrane of mitochondria11. What is the cellular (and subcellular, if relevant) location of Hexokinase?Cytoplasm12. What is the cellular (and subcellular, if relevant) location of Pyruvate dehydrogenase?Matrix of mitochondria13. What is the cellular (and subcellular, if relevant) location of Aldolase?Cytoplasm14. What is the cellular (and subcellular, if relevant) location of Citrate synthase?Matrix of mitochondria15. What is the cellular (and subcellular, if relevant) location of NADH dehydrogenase complex?Inner membrane of mitochondria 16. When the cell reaches the threshold potential, what kind of ions help depolarize the membrane?Sodium17. When the cell reaches the threshold potential, how do the ions depolarize the membrane?By moving into the cell18. What can be done to alter phospholipids to increase membrane fluidity?Shortening the hydrocarbon tails and increasing the double bonds in hydrocarbon tails19. What ways can phospholipids move spontaneously within a membrane bilayer?By flexion of hydrocarbon tails, by rotating along their long axis, and by lateral diffusion within a monolayer.20. True or false. Cholesterol is an amphipathic moleculeTrue21. Detergents can solubilize both membrane phospholipids and membrane proteins. What kind of molecules are they?Amphipathic22. Give a description of the primary structure of a protein.Amino acid sequence23. Give a description of the secondary structure of a protein.Stable folding patterns within a polypeptide24. Give a description of the tertiary structure of a protein.Full 3D conformation25. Give a description of the Quaternary structure of a protein.Complete structure of a complex formed between subunits26. What kind of bond/interaction is responsible for the formation of alpha-helices and beta-sheets in proteins?Hydrogen bonds27. What does protein phosphorylation do to an enzyme to reversibly alter the enzyme activity?Changes the enzyme’s conformation28. When does feedback inhibition take place?When an enzyme acting early in a reaction pathway is inhibited by a late productof that
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