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EXAM VERSION 99
UNIVERSITY OF TORONTO
Faculty of Arts and Science
Tuesday, April 24, 2007
From 2-5 pm
DURATION: three (3) hours (180 minutes)
No Examination Aids Allowed
Number of pages: 25 (not including this one) Number of questions: 75 multiple choice
This examination is worth 30% of your final mark.
INSTRUCTIONS: Please read carefully!
1. Questions 1- 50 are based on lecture material (Sections III and IV), questions 51 – 75 are
based on labs 7 - 12. You are to choose the BEST answer; there is ONE and only one correct
answer per question (multiple answers for a question will be marked wrong). There is no
additional penalty for incorrect answers, so do NOT leave any questions unanswered
(blank) on your answer sheet. Write your name on your exam question paper.
2. Green Computer Answer Sheet: SCANTRON(See sample on the back of this page)
Transfer your answers to the computer scantron answer sheet using a soft lead pencil and
darken inside one box ONLY as multiple answers will be marked wrong. Erase all
corrections completely. ONLY your answer sheet will be marked. On the left side of your
computer answer sheet:
a) Print your last name in the boxes provided, and darken the appropriate letters in
each column. Print your first name initial(s) in the far right columns and darken the
b) Print your student number and carefully darken the appropriate numbers. Do not
leave this section blank.
c) Print the exam version in "CODE" and darken in the appropriate numbers. The
exam version is at the bottom of every page of this exam.
Hand in BOTH your COMPUTER ANSWER SHEET and your Exam PAPER
Version 99 2 Continued
Version99 3 Continued
1. Which of the following statements concerning the composition of cell membranes is
a) Plasma membranes contain lipid rafts that are rich in phospholipids with short fatty acid
b) Phosphatidylserine is found in high concentrations in the outer leaflet of the plasma
c) Phospholipids in the plasma membrane can be covalently modified during cell
d) The percentage of specific phospholipids is the same for all cellular membranes.
e) Glycolipids are found in higher amounts in the cytosolic leaflet of the plasma membrane.
2. You would like to determine how a specific membrane protein is anchored to the plasma
membrane. You express a fusion protein in cells in which the protein of interest is fused to
GFP. As expected, most of the fluorescence is localized to the plasma membrane. You then
add phospholipase C to the medium bathing the cells. The fluorescence disappears from the
membrane. What can you conclude?
a) The protein is anchored via its transmembrane region, which is composed of amino acids.
b) The protein is a peripheral protein.
c) The protein is anchored via a prenyl anchor.
d) The protein is anchored via a glycosylphosphatidylinositol anchor.
e) The protein is anchored via a fatty acid chain.
3. Which of the following is a step in the model of Na+/K+ pump action?
a) The pump is not phosphorylated, instead the hydrolysis of ATP simply provides energy.
b) In one conformation, 3 Na+ ions bind to high affinity sites on the extracellular face.
c) Na+ ions dissociate from low affinity sites on the cytosolic face.
d) Na+ ions and K+ ions are transported through the pump simultaneously.
e) In one conformation, 2 K+ ions bind to high affinity sites on the exoplasmic face.
4. Glucose uniporters are a family of proteins that transport glucose. Which of the following
concerning these uniporters is CORRECT?
a) GLUT-2 has a high Km indicating that it has a high affinity for glucose.
b) GLUT-4 is localized to plasma membranes of fat and muscle cells when insulin levels are
c) GLUT-1 supplies glucose to most cells of the body independent of insulin
d) GLUT-1 has a low Km indicating that it has a low affinity for glucose.
e) At low glucose concentrations, the rate of transport through GLUT-2 is faster than the
rate of transport through GLUT-1.