22.Which of the following explains are the enzyme effects?
(A) Enzymes release products very rapidly
(B) Enzymes can lower product energy
(C) An enzyme stabilizes the transition state of the reaction
(D) An enzyme can convert a normally endergonic reaction into an exergonic reaction
(E) An enzyme lowers the energy of activation only for the forward reaction

18. In humans, gluconeogenesis: (A) can result in the conversion of protein into blood glucose. (B) helps to reduce blood glucose after a carbohydrate-rich meal. (C) is activated by the hormone insulin. (D) is essential in the conversion of fatty acids to glucose. (E) requires the enzyme hexokinase.

19. Which of the following is (are) NOT found as covalently attached anchors in lipid-linked proteins? (A) isoprenoid groups (B) fatty acids (C) cholesterol and other sterols (D) glycosylphosphatidyl inositol groups (E) All of the above are found as covalently attached anchors in lipid-linked proteins.

20. Aspirin inhibits the synthesis of which of the following sets of eicosanoids? (A) Prostaglandin E2 and leukotriene A4 (B) Thromboxane A2 and leukotriene C4 (C) Prostaglandin F2 and thromboxane A2 (D) Prostaglandin A2 and 5-hydroperoxyeicosatetraenoic acid (E) Thromboxane A2 and 5-hydroperoxyeicosatetraenoic acid

21. In which metabolic pathway does glucose-6-phosphate dehydrogenase play a key role? (A) glycogenesis (B) glycolysis (C) gluconeogenesis (D) glycogenolysis (E) pentose phosphate pathway

23. Enzymes are biological catalysts that enhance the rate of a reaction by: (A) decreasing the activation energy. (B) decreasing the amount of free energy released. (C) increasing the activation energy. (D) increasing the amount of free energy released. (E) increasing the energy of the transition state.

24. To determine the isoelectric point of a protein, first establish that a gel: (A) contains a denaturing detergent that can distribute uniform negative charges over the protein's surface. (B) exhibits a stable pH gradient when ampholytes become distributed in an electric field. (C) is washed with an antibody specific to the protein of interest. (D) neutralizes all ionic groups on a protein by titrating them with strong bases. (E) relates the unknown protein to a series of protein markers with known molecular weights, Mr.

25 Which of the following lipids can be formed by the methylation of phosphatidylethanolamine? (A) Phosphatidylinositol (B) Phosphatidylcholine (C) Phosphatidylserine (D) Sphingomyelin (E) Lysophosphatidylcholine

26. Which volatile short-chain fatty acid is believed to lower serum cholesterol by acting as an inhibitor of cholesterol biosynthesis? (A) acetic (B) butyric (C) propionic (D) palmitic (E) lauric

27. Which of the following techniques was NOT used to determine the three-dimensional structure of (A) NMR spectroscopy (B) X-ray diffraction (C) Cryogenic electron microscopy (D) UV/Vis spectroscopy (E) All of the above

28. Which of these statements is generally true of integral membrane proteins? (A) A hydropathy plot reveals one or more regions with a high hydropathy index. (B) The domains that protrude on the cytoplasmic face of the plasma membrane nearly always have covalently attached oligosaccharides. (C) They are unusually susceptible to degradation by trypsin. (D) They can be removed from the membrane with high salt or mild denaturing agents. (E) They undergo constant rotational motion that moves a given domain from the outer face of a membrane to the inner face and then back to the outer.