1. Although cholestrol is a hydrophobic molecule. It has a hydrophilic head grou
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Question
1. Although cholestrol is a hydrophobic molecule. It has a hydrophilic head group like all other membrane lpids. (a) TRUE (b) FALSE2. Phosphatidylserine is the most abundant type of phospholipid found in cell membranes (a) TRUE (b) FALSE
3. Glycolipids lack the glycerol component found in phospholipids (a) TRUE (b) FALSE
4. Which of the following membrane lipids does not contain a fatty acid tail? (a) Phosphatidylcholine (b) a glycolipid (c) Phosphatidylserine (d) cholestrol
5. Which of the following statements is true?
(a) Phospholipids will spontaneously form liposomes in nonpolar solvents
(b) In eukaryotes, all membrane enclosed organelles are surrounded by one lipid bilayer
(c) Membrane lipids diffuse within the plane of the membrane
(d) Membrane lipids frequenly flip flop between one monolayer and the other
6. Membrane lipids are capable of many different types of movement. Which of these does not occur spontaneously in biological membranes?
(a) switching between lipid layers
(b) lateral movement
(c) rotation
(d) flexing of hydrocarbon chains
7. Membrane synthesis in the cell requires the regulation of growth for both halves of the bilayer and the selection retention of certain types of lipids on one side of the other. Which group of enzymes accomplishes both of these tasks?
(a) flippases
(b) phospholipases
(c) convertases
(d) glycolases
8. Bacterial porin proteins form large, barrel like channels in the membrane. Which of the following is not true about these channels
(a) they are made primarily of alpha helices
(b) ther are made primarily of beta sheets
(c) they cannot form narrow channels
(d) they have alternating hydrophobic hydrophilic amino acids
9. Plasma membranes are extremely thin and fragile, requiring an extensive support network of fibrous proteins. This network is called the
(a) cell cortex
(b) attachment complex
(c) extracellular matrix
(d) gap junction
10. When a mouse cell is fused with a human cell, the movement of the respective membrane proteins is restricted to their original locations at the time of fusion (a) TRUE (b) FALSE
11. Epithelial cell membranes are asymmetric, and proteins from the apical side of the cell membrane cannot diffuse into the basal side of the membrane (a) TRUE (b) FALSE
12. The only role of the carbohydrate layer on the cell surface is to absorb water, which creates a slimy surface and prevents cells from sticking to each other (a) TRUE (b) FALSE
13. Although the extracellular environment has a high sodium ion concentration and the intracellular environment has a high potassium ion concentration, both must be neutralized by negatively charged molecules. In the extracellular case, what is the principal anion?
(a) HCO-3 (b) Cl- (c) PO3-4 (d) OH-
14. We can test the relative permeability of a phospholipid bilayer by using a synthetic membrane that does not contain any protein components. Some uncharged, polar molecules are found to diffuse freely across these membranes, to varying degrees. Which of the following has the lowest rate of diffusion across an artificial membrane?
(a) glucose (b) water (c) glycerol (d) ethanol
15. Faciliated diffusion can be described as the favorable movement of one solute down its concentration gradient being coupled with the unfavorable movement of a second solute up its concentration gradient. (a) TRUE (b) FALSE
16. Transporters undergo transitions between different conformations, depending on whether the substrate binding pocket is empty or occupied. (a) TRUE (b) FALSE
17. The net negative charge on the cytosolic side of the membrane enhances the rate of glucose import into the cell by a uniporter (a) TRUE (b) FALSE
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