genetically 23. You wish to produce a human enzyme, protein A, by introducing it
ID: 205371 • Letter: G
Question
genetically 23. You wish to produce a human enzyme, protein A, by introducing its gene into bacteria. The engineered bacteria make large amounts of protein A, but it is in the form of an insoluble aggregate with no enzymatic activity. Which of the following procedures would definitely NOT be worth trying in order to obtain soluble, enzymatically active protein? A) Make the bacteria synthesize protein A at a lower rate and in smaller amounts. B) Dissolve the protein aggregates in urea, then dilute the solution and slowly remove the urea. C) Treat the insoluble aggregate with a protease. D) Make the bacteria overproduce chaperone proteins in addition to protein A 24. Which of the following membrane lipids does NOT contain a fatty acid tail? A) Phosphatidylcholine C) Phosphatidylserine B) Glycolipid D) Cholesterol 25. A bacterium is suddenly expelled from a warm human intestine into the cold world outside. Which of the following adjustments might the bacterium make to maintain the same level of membrane fluidity? A) Produce lipids with hydrocarbon tails that are longer and have fewer double bonds. B) Produce lipids with hydrocarbon tails that are shorter and have more double bonds. C) Increase the amount of cholesterol in the membrane. D) Decrease the amount of glycolipids in the membrane. 26. Which of the following statements is true? A) Phospholipids will spontaneously form liposomes in nonpolar solvents. B) In eucaryotes, all membrane-enclosed organelles are C) Membrane lipids diffuse within the plane of the membrane. D) Membrane lipids frequently flip-flop between one monolayer and the other surrounded by one lipid bilayer. 27. Cholesterol serves several essential functions in mammalian cells. Which of the following is not influenced by cholesterol? A) membrane permeability B) membrane fluidity C) membrane rigidity D) membrane thickness 28. We know the detailed molecular structure and mechanism of action of the transmembra bacteriorhodopsin. This protein uses sunlight as the source of energy to pump ne protein cell. out of A) ATP C) K+ B) H+ Na mbranes are extremely thin and fragile, requiring an extensive support network of fibrous proteins: This network is called the A) cortex C) cytoskeleton B) attachment complex D) spectrin 30. The endothelial cells found closest to the site of an infection express proteins ca binds lled lectins. Each lec bs iahardet is presented on the surface of a target cell B) aminophospholipid C) polysaccharide D) sphingolipid
Explanation / Answer
Answer 24 D) Cholesterol
Answer 25 B) Produce lipids with hydrocarbon tails that are shorter and have more double bonds.
Answer 26 C) Membrane lipids diffuse within the plane of the membrane.
Answer 27 D) membrane thickness.
Answer 28 B) H+.
Answer 29 A) cortex.
Answer 30 A) oligosaccharide.
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