Quiz 3, BICH 410 (MWF3-3:50), Friday, Oct. 16, 1998
Clearly circle the letter corresponding to your answer for each problem. There are six problems, four of which count 3 points, and two for 4 points. No partial credit given for multiple-choice questions.
gas constant R 8.315 J/mole-K; Faraday constant F 96.5 kJ/mole-volt
1) A sphingolipid that contains a single monosaccharide residue as part of its polar head group is known as a:
- A) sterol
- B) cerebroside
- C) ganglioside
- D) triacylglycerol
- E) glycerophospholipid
2. Which of the following would you expect to be least soluble in water?
- A) palmitic acid (16:0)
- B) oleic acid (18:1cdelta9)
- C) glycerol
- D) a wax derived from oleic acid (18:1cdelta9) and oleyl alcohol
- E) inositol
3) Which of the following statements is true about the passive transport of water across membranes?
- A) The rate of its transport is saturable.
- B) Diffusion of water establishes a membrane electrical potential.
- C) The permeability coefficient for water is greater than that for glucose.
- D) Since water is polar it does not diffuse across membranes without the aid of a pore.
- E) Valinomycin inhibits the passive transport of water.
4) Which of the following statements is not true about glycosaminoglycans?
- A) Glycosaminoglycans are the carbohydrate components of proteoglycans.
- B) Chondroitin sulfate is a glycosaminoglycan.
- C) Glycosaminoglycans are heteropolysaccharides.
- D) Glycosaminoglycans carry negative charges at neutral pH.
- E) Glycosaminoglycans are polysaccharides in which the monosaccharide subunits are joined by beta(1->4) and beta(1->6) linkages.
5) (4 pts) Which of the following structures shows the linkage found in an N-linked glycoprotein?
Answer: C; asparagine side-chain N-C bond to C-1 of N-acetyl-glucosamine
6) (4 pts) What is the free energy change for the transport of calcium ions (Ca+2) across a membrane from a region (left) where the concentration is 100 micromolar to a region (right) where the concentration is 1 micromolar. A membrane potential of 50 mV exists across the membrane where the left side is more negative than the right side. The temperature is 37 C.
Answer: B; deltaG = RT ln([Ca+2]right/[Ca+2]left) + ZF(membrane potential)
- A) -21.5 kJ/mole
- B) - 2.2 kJ/mole
- C) -7.1 kJ/mole
- D) +2.2 kJ/mole
- E) +21.5 kJ/mole
deltaG = (8.315 J/mole-K)(310 K) / (1000 J/kJ) ln (1/100) + (2)(96.5 kJ/mole-volt)(.05 volt)
deltaG = -2.2 kJ/mole