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BL A512 -- Signal Transduction Fall -- 1996
Midterm Exam -- October 15, 1996 -- Part I
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1. What
(a) lighting conditions and (a) dark
(b) gating conditions (b) high cGMP in
keep the cell depolarized
as shown in this figure?
(2 points)

2. What
(a) enzyme liberates
(b) what intermediate by
(c) what pathway to create
(d) what class of substances? (a) PLA2
(4 points) (b) arachidonic (20:4)
(c) cycloxigenase
(d) prostaglandins

3. What
(a) precursor is split by
(b) what enzyme to make (a) PIP2
(c, d) what substances which do (b) PLC-b
(e, f)what? (c, d) IP3 & DAG
(abbreviations will suffice) (e) liberate Ca2+
(6 points) (f) activate PKC

4. What
(a) specific adaptation of
(b) what general technique is shown?
(c) How high
is the resistance (a) detached
between membrane and tip? (b) patch clamp
(d) Name one of the 2 Nobel Prize (c) big: gig Ohm
winners for developing (b). (d) Neher
(4 points) Sakmann

5. (a) What is the name (a) phosphatidylcholine
of this particular (b) acetylcholine
(b) What neurotransmitter
utilizes the same polar
head group as shown here?
(2 points)

6. (a) What type of ligand (a) enzyme
receptor (e.g. channel, etc) (tyrosine kinase)
is this? (b) insulin
(b) Name one of the ligands. IGF-1
(2 points)

7. (a) What "presynaptic" channel is (a) Ca2+
necessary for vesicle release? (b) AChR
(b) What is this channel in the (c) Ca2+
vertebrate end plate?
(c) What does this channel release?
(3 points)

8. Compare (a) connexin, (b) the Shaker K+ channel, (c) the Electrophorus Na+ channel, and (d) the CFTR in terms of (I) number of membrane-spanning a-helices per molecule and (II) number of molecules per channel. (8 points)

a b c d

I 4 6 24 12

II 6 4 1 2

9. What do monamine oxidase (MAO) and catechol-O-methyl transferase (COMT) do? (1 point)
break down norepinephrine

10. (a) What does the insecticide malathion (and related nerve gasses) do at the chemical level? (b) How would a victim of poisoning by such an organophosphate die? (c) What Nobel laureate's pioneering research on "vagus stuff" relates to this physiological mechanism of death? (3 points)
(a) inhibit acetylcholinesterase
(b) heart would stop
(c) Loewi

11.What does botulism toxin do? (1 point)
inhibit vesicle release

12. What happens to what conductance during the IPSP of the spinal motorneuron? (2 points)

chloride conductance increases

13. What is the natural neurotransmitter whose receptor is stimulated by the agonist NMDA? (1 point)


14. a-bungarotoxin binds irreversibly to what signalling molecule (1 point)

nicotinic AChR (channel)

15. (a) What is the physical term
for the slope of this line and (a) conductance
(b) what units does it come in? (b) Siemens
(2 points)

16. "Disease" - channel matching (use each answer one time) (one point each)

e long QT syndrome a. related to epithelial sodium channels
c cystic fibrosis (ENaCs) sensitive to amiloride
f peripheral nerve degeneration b. Ca2+-dependent K+ channel via CaM
a C. elegans mechanosensory c. has ATP-binding and charged R domain
receptor degeneration d. autoimmunity to AChR
d myasthenia gravis e. human ether-a-go-go related
g diabetes insipitus f. connexin-32
b Paramecium pantophobiac g. aquaporin

17. What does Duchenne muscular dystrophy have to do with the mechanogated channel? (1 point)

dystrophin can be a cytoskeletal component linked to it

18. (a and b) Label the axes on this graph of the work from the Nobel Prize winners Hodgkin and Huxley. (c) What does the downward part of the curve represent? (d) What does the upward part of the curve represent? (4 points)
(c) inward sodium current
(d) delayed outward potassium current

19. (a) In terms of amino acids, what is special about the S4 domain of the A-current channel? (b) What is this segment thought to mediate? (2 points)

(a) charged arginines every 3-4
(b) voltage gating

20. (a) What kind of a library from sweat glands was used to clone the cystic fibrosis gene? (b) Why were sweat glands chosen? (c) What substance is conducted through this channel? (d) What neurotransmitter uses a channel conducting the same substance? (4 points)
(a) cDNA (b) something abnormal there - CF patients are salty
(c) chloride (d) GABA

21. (a) How big of a portion of (b) what molecule is a "response element" and (c) what kind of a receptor interacts with a response element? (3 points)
(a) maybe a half dozen bp of (b) DNA
(c) nuclear (steroid etc) hormone receptor (protein)
22. (a) What is a Pacinian corpuscle and (b) what are its special properties? (2 points)
(a mechanoreceptor in the skin which is (b) phasic (rapidly adapting
Print your name neatly here->> * *
BL A512 -- Signal Transduction Fall -- 1996
Midterm Exam -- October 15, 1996 -- Part 2

1. Label the following components of the bacterial falgellum. (4 points)

2. Explain the adaptation response to chemotaxis in bacteria. (2 points)

Over time in a given concentration of attractant, a bacterium will resume its
original swim/tumble routine.

3. A bacterial flagellum moves (a) in what direction? during a swim and (b) in what direction? during a tumble. (2 points)

(a) counterclockwise
(b) clockwise

4. What three components of signal processing in bacterial chemotaxis tend to be arranged in modules (3 points)

Receptor or environmental detector
Histidine Kinase which autophosphorylates
Response regulator phosphorylated by the histidine kinase

5. Adaptation relies on the methylation of which residues on the cytoplasmic face of the receptor? (1 point)


6. How could you experimentally determine whether a given chemical is a chemoattractant? (3 points)
Place the chemical in a capillary tube then suspend the tube in a culture
of bacteria to see if the bacteria "flock" toward the capillary tube.
or: Use a microscope to observe the amount of swimming after addition
of the chemical.
or: Make some soft agar with the chemical in it, touch a spot with
bacteria onto the agar. If a regular colony forms, then the chemical is not an
attractant. If rings of growth appear, then that means that the bacteria are spreading out into the agar to get fresh chemoattractant, and thus the chemical is an attractant.

7. What will happen if you deprive a bacterium of S-adenosylmethionine in a given concentration of attractant or repellent? (2 points)
The bacterium will not be able to adapt, i.e. no methylation of chemotaxis proteins.
or: The bacterium will respond to phosphotransferase sugars.
8. Match the terms on the left with descriptions on the right. Each term will have two descriptions. Each is to be used only once. (12 points)

cf CheR (a) Its 15 kD N-terminal region is regulatory.
(b) has autophosphatase activity
ei CheW (c) methyltransferase
(d) methylesterase
kl CheZ (e) regulates autokinase activity of CheA
(f) not regulated
ad CheB (g) has histidine kinase activity
(h) phosphorylated by CheA
gj CheA (i) Two of these monomers bind one CheA dimer.
(j) heterodimer
bh CheY (k) dephosphorylates CheY
(l) forms multimers of 39 kD

9. How does the phosphotransferase sugar (PTS) system work in bacterial chemotaxis? A diagram might be helpful in describing this system. (5 points)
Sugars are transported into the cell by group translocation and become phosphorylated during translocation. This group translocation causes a chemotactic response toward the sugar source.

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