BIOLOGY BIO130 VersionA

BIOLOGY BIO130 VersionA 1. Phospholipids are . a. hydrophobic molecules with a polar head group and non-polar tails. b. amphipathic molecules with a polar head group and hydrophobic tails. c. amphipathic molecules with a hydrophobic head group and hydrophilic tails d. hydrophilic molecules with a polar head group and non-polar tails. 2. Which of the following BEST describes how a bacterium would respond as temperature is lowered? It would….. a. reduce the fluidity of the membrane by removing cholesterol from the membrane. b. reduce the fluidity of the membrane by removing phospholipid translocator proteins. c. maintain the fluidity of the membrane by producing phospholipids with shorter tails and introducing cis- double bonds in these tails. d. It increase the fluidity of the membrane by removing cis-double bonds from phospholipid tails and shortening these tails. 3. Which of the following is an exoplasmic face? a. The leaflet of the inner mitochondrial membrane that faces the matrix. b. The leaflet of a vesicle membrane that faces the lumen. c. The leaflet of the inner nuclear membrane that faces the inside of the nucleus d. All of the above. 4. Which of the following BEST describes the FRAP data shown below? a. The transmembrane proteins in II are more mobile than in III and IV, but less mobile than in I. b. The least mobile transmembrane proteins are in I. c. It is likely that cytosolic proteins were photobleached in III and IV, but not in I and II. d. The transmembrane proteins in I are more mobile than in III and IV, but less mobile than in II. 5. You have been studying protein X which you observe to be sorted through the endomembrane system to the plasma membrane. This protein is most likely . a. a GPI anchored protein on the exoplasmic face of the plasma membrane. b. a prenyl anchored protein on the exoplasmic face of the plasma membrane. c. a prenyl anchored protein on the cytosolic face of the plasma membrane. d. a GPI anchored protein on the cytosolic face of the plasma membrane. 6. Multipass integral membrane proteins are . a. hydrophobic. b. hydrophilic. c. amphipathic. d. channel proteins but not transporters. 7. Which of the following most directly stops net transport by the Na+/glucose symporter? a. Decreasing ATP. b. Reversing the glucose concentration. c. Equalizing the Na+ electrochemical gradient on both sides of the membrane. d. Increasing Na+/K+ pump activity. 8. A toxicologist is trying to determine how a particular poison works. She decides to culture epithelial cells and then adds the poison. The membrane potential immediately changes from approximately -100 mV (without the poison) to approximately -10 mV (with the poison). Which of the following hypotheses is the most logical? a. The poison stops the activity of K+ leak channels. b. The poison increases the activity of lysosomal V-type ATPases. c. The poison stops the activity of ABC transporters. d. The poison stops the activity of Na+/H+ exchangers. 9. Which of the following is correctly ordered from the molecule which moves the fastest across a lipid bilayer (with no transport proteins) to the molecule which moves the slowest? a. Water, Oxygen, Glucose, Sodium ions, DNA. b. Glucose, Oxygen, Water, DNA, Sodium ions. c. Oxygen, Water, Glucose, Sodium ions, DNA. d. Oxygen, Water, Glucose, DNA, Sodium ions. 10. How would the Na+/H+ exchanger respond to a decrease in cytosolic pH? a. It increases the rate that H+ is pumped out of the cell and Na+ is pumped into the cell. b. It increases the rate that H+ and Na+ are pumped into the cell. c. It decreases the rate that H+ is pumped out of the cell and Na+ is pumped into the cell. d. It decreases the rate that H+ and Na+ are pumped into the cell. 11. During the pumping cycle of the Na+/K+ pump, which of the following BEST describes an occluded conformation? a. Bound to two K+ ions and releasing three Na+ ions. b. Bound to either two K+ ions or three Na+ ions. c. Bound to three K+ ions and releasing two Na+ ions. d. Bound to either three K+ ions or two Na+ ions. 12. Which of the following is required for transcellular transport of glucose across the epithelial cells that line the small intestine? a. K+ from the lumen of the intestine. b. Na+ from the lumen of the intestine. c. A higher concentration of glucose in the blood stream than in the cytosol of the epithelial cell. d. A higher concentration of Na+ in the cytosol of the epithelial cell than in the extracellular fluid on the basolateral side of the epithelial cell. 13. If a mutation in the signal sequence delivered the ATP synthase complex to the lysosome membrane with the ATPase domain located in the cytosol, what would you expect to observe? a. If no ATP was available in the cytosol, the ATP synthase would acidify the lysosome lumen. b. If ADP was not available, the ATP synthase would acidify the cytosol. c. As long as a supply of ATP was available in the cytosol, the ATP synthase would function like a V-type ATPase. d. The ATP synthase would not allow any protons to move across the membrane. 14. A bioinformatician is searching the genome for genes that encode for secreted proteins. Which of the following should she look for? Genes that encode for… a. introns (splice sites) close to the start codon. b. proteins that are entirely hydrophilic. c. proteins with hydrophilic amino acids at both their N-terminus and C-terminus, with hydrophobic amino acids in the middle. d. proteins with hydrophobic amino acids at their N-terminus. 15. Which of the following allows for unregulated free diffusion of Ca++? a. Vesicular membranes. b. Peroxisomal membranes. c. The nuclear pore complex. d. The endoplasmic reticulum translocator. 16. What might you conclude about a protein in the endoplasmic reticulum that does not bind to any membrane associated sorting receptors in the endoplasmic reticulum membrane? a. It is a protein that is normally resident in mitochondria but the signal sequence has been mutated. b. It is a protein that is resident in the Golgi apparatus. c. It is a protein that is resident in a peroxisome. d. It is a protein that is resident in the endoplasmic reticulum. 17. Actin proteins are .