BIO 241
MIDTERM I
31 October 2005
Pledge of Honor
Name: ________________________
By signing my name above I pledge (promise) that I will NOT cheat
during this exam. Cheating is defined as using assistance from notes or
from other students taking the exam, as well as helping or trying to help
others.
page 1:
page 2:
page 3:
page 4:
_________(20 pts)
_________(29 pts)
_________(30 pts)
_________(21 pts)
Total pts: _________(100 pts)
Note: Please, write your name on top of every page.
GOOD LUCK!!!
Student: _________________________________________________________
Imagine that you just started your doctoral thesis. Your boss asks you to continue a promising project
by another Ph.D. student who just graduated. He has generated some materials. Now you have to decide
which of the available materials you can use and which are crap.
His/Her goal was to clone the cDNA for the “SüperZeki” gene into an expression plasmid and multiply
it in E. coli. He/She performed the following reactions and he/she gave you the tubes with the following
(see extra sheet for diagrams):
a) plasmid undigested
e) cDNA undigested
b) plasmid digested with Kpn I
f) cDNA digested with KpnI
c) plasmid digested with Sac I
g) cDNA digested with Sac I
d) plasmid digested with KpnI and SacI
h) cDNA digested with KpnI and SacI
Question 1. If you know that the start codon in the cDNA is near the KpnI site; the promoter sequence
of the plasmid is upstream of the KpnI site and that the Sac I site in the plasmid is upstream of
terminator sequences which ligation reaction (which plasmid + which cDNA) will give you the fastest
result? Please, provide the DNA sequence at the junctions after ligation. (10 pts)
Question 2. You performed the ligation reaction by now but you are not sure whether everything worked
out as you planned. How would you prove that the ligation worked perfectly? (5 pts)
Question 3. You are now 100% sure that you have a good expression vector with the cDNA for the
“SüperZeki” gene in the correct orientation. At this step you have to introduce it into E.coli, which
cannot naturally uptake DNA. How would you overcome this problem? How would you make sure that
the bacteria do not loose your favourite gene’s plasmid after you put it in?
(5 pts)
1
Student: _________________________________________________________
Question 4. What is the difference between genomic DNA and complementary DNA (cDNA). (5 pts)
Question 6. Which of the following is not found in membranes: (2 pts)
A. cholesterol
B. phosphatidylcholine
C. phospatidylserine
D. phosphatidylinositol
E. spectrin
Question 7. How is the asymmetry in the plasma membrane generated. (10 pts)
Question 8. Which of the following cannot passively diffuse through the membrane? (2 pts)
A.
B.
C.
D.
E.
F.
oxygen
carbon dioxide
nitrogen
water
glycerol
glucose
Question 9. The extracellular concentration of Na + is 145 mM and the intracellular K+ concentration is
140 mM. How does the cell maintain these concentration gradients? (10 pts)
2
Student: _________________________________________________________
Question 10. Describe how glucose is transported across the apical surface of the gut epithelial cells and
how it is delivered to the blood on the basolateral side. (10 pts)
Question 11. What kind of ion channels initiate action potentials? What determines the direction in
which an action potential will propagate? (10 pts)
Question 12. After an action potential reaches the nerve terminal how is the signal propagated to the
post-synaptic cell? (10 pts)
3
Student: _________________________________________________________
Question 13. Which of the following take(s) part in the docking step when a vesicle reaches its target?
(2 pts)
A.
B.
C.
D.
E.
v-SNARE
t-SNARE
clathrin
dynamin
v-SNARE + t-SNARE
Question 14. Proteins destined to become resident in the ER loose their ER signal peptides. (2 pts)
TRUE FALSE
Question 15. ER proteins are being synthesized into the ER lumen directly while still bound to
polyribosomes. (2 pts)
TRUE FALSE
Question 16. Proteins loose their glycosylation in the ER and then it is added back in the Golgi. (2 pts)
TRUE FALSE
Question 17. The trans-Golgi receives vesicles from the ER and the cis-Golgi sends vesicles to the
plasma membrane. (2 pts)
TRUE FALSE
Question 18. Which of the following enzymes is(are) NOT found in the lysosome: (2 pts)
A. nucleases
B. proteases
C. glycosidases
D. lipases
E. phosphatases
F. sulfatases
G. phospholypases
H. acid hydrolases
I. basic hydrolases
Question 19. If the secretory vesicles keep fusing with the plasma membrane how come the cell volume
does not keep expanding all the time? Where is the extra membrane stored? (9 pts)
4