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BL A512 -- Signal Transduction Fall -- 1996
Final Exam -- December 10, 1996 TOTAL POINT VALUE = 115
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1. For the average person, how many copies of genes coding for cone rhodopsins are on the X chromosome? (1 point)
Many (more than 2)

2. An activated seven-transmembrane-domain receptor and the "son of sevenless" proteins each cause (a) what molecule to be ejected from (b-c) what molecules respectively? (3 points)
(a) GDP (b) G-alpha (c) ras

3. What are the G proteins (2) used to mediate bitter taste? (2 points)
(a) gusducin (b) transducin

4. Describe the molecule encoded by the Notch gene in terms of (a) its location, (b) its function at this location, (c) its structure, (d-f) its domains, and (g) an "upstream" molecule which interacts with it. Use a diagram if you want. (7 points).
(a) transmembrane (b) receptor (c) with one membrane pass
(d-e-f) extracellular EGF & Ln repeats, intracellular Cdc-10 & PEST
(g) Delta or Serrate

5. Retinol is dehydrogenated to (a) what molecule which subserves (b) what function? If the molecule you named in "a" (above) is further dehydrogenated, (c) what molecule is formed and (d) what does that molecule do? (4 points)
(a) retinal (b) rhodopsin chromophore (c) retinoic hormone
(d) nuclear hormone (morphogen)

6. Molecule - function matching (1 point each)

c brassinosteroids a. vesicle release
e tumor necrosis factor b. inactivate phosphorylated rhodopsin
g a and a factors c. photomorphogenesis
a rabphilin 3A d. calcium phototransduction channel
f folic acid e. ligand for apoptosis pathway
h ubiquitin f. prey detectiuon by slime molds
d TRP g. mating specificity in yeasts
b S-antigen (48kD protein) h. protein degradation

7. What molecule is known for its WD propellers? (1 point)
beta subunit of heterotrimeric G protein

8. What molecular or genetic mechanism mediates the considerable variability of olfactory receptor molecules in the human? (1 point)
just lots of genes (not splicing or anything like in immunology

9. (a) Chemically, what kind of a molecule is 14-3-3 and (b) to what molecule does it bind? (2 points)
(a) protein (b) phosphorylated raf

10. (a) What molecule is in low abundance in Parkinson's Disease and (b) where? (c) What precursor is given to ameliorate the symptoms and (d) why would anti-muscarinics be of use? (4 points)
(a) dopamine (b) nigro-striatal, motor control (or the like) in brain
(c) l-DOPA (d) decrease ACh function since ACh -DA balance is important

11. What is the relationship between cyclophilin and rhodopsin? (1 point)
might help folding or be a chaperone

12. GAP (GTPase-activating protein) acts on what molecule? (1 point)
ras (which is bound to GTP

13. Myasthenia gravis affects (a) what specific receptor (b) at what cellular site because of an autoimmunity most commonly originating in (c) what body structure? (3 points)
(a) nicotinic ACh (b) motor end plate (c) thymus

14. Pathway -> downstream cascade step matching (1 point each)

e wingless a. cGMP PDE
f salicylic acid b. cubitus interruptus
h Drosophila vision c. RAR - RXR dimer transcription factor
c nuclear hormone d .interleukin 1-b converting enzyme
a vertebrate phototransduction e. dishevelled
b hedgehog f. catalase
d apoptosis g. drk=downstream of receptor kinase
g formation of R7 h. norpA PLC-b

15. Agrobacterium causes the overproduction of what two traditional hormone classes to cause overgrowth? (2 points)
auxins and cytokinins

16. After maternal genes have finished controlling early Drosophila development, but before homeotic genes take over, (a) what kind of genes function and (b, c, d) what three types function (list in order) (4 points)
(a) zygotic (b-d) gap, pair-rule, segment polarity

17. (a) Chemically and (b) functionally, what kind of a molecule is erythropoietin? (c) In the adult, where is it made? (3 points)
(a) protein (b) ligand (c) kidney

18. In what way is the channel regulation in the olfactory receptor (a) similar to and (b) different from channel control in the vertebrate rod?
(a) cyclic nucleotide gated channel
(b) stimulation opens channel (in olfaction)

19. (a) What extracellular ligand is secreted in the anterior direction to mediate progression of the morphogenetic furrow and (b) what other signalling molecule is induced by this substance? What vetrebrate molecule is homologous to this latter? (3 points)
(a) HH (b) Dpp (c) TGF-beta

20. In Dictyostelium discoideum, thepdsA gene codes for a phosphodiesterase which performs (a) what reaction (b) where? (2 points)
(a) break down cAMP (b) outside the cell

21. What mediates the interaction of calcium and the guanylyl cyclase in the vertebrate rod? (1 point)
GCAPs=gualylate cyclase activating proteins

22. The T-DNA technique is based on (a) what component of (b) what organism and allows researchers to do (c) what? (3 points)
(a) Ti plasmid (b) Agrobacterium tumefaciens
(c) isolate plant genes

23. (a) What does "ERK" stand for and (b) what "alias" is quite frequently used instead of ERK? (2 points)
(a) extracellular signal regulated kinase
(b) mitogen activated protein kinased

24. The A subunit of the toxin of Vibrio cholera adds (a) what chemical group to (b) what specific molecular component? That causes an increase in (c) what intracellular "second messenger" to affect (d) what channel? (e) To what molecule does the B subunit bind, and (f) where is this molecule? (6 points)
(a) ADP-ribose (b) Gs (c) cAMP (d) CFTR (e) GM1 (f) membrane
25. In yeast, the b-adrenergic receptor can be used to replace what molecule which is structurally related but not homologous? (1 point)
a or a factor receptor

26. What is the function of the addition of a farnesyl group to the g subunit of the heterotrimeric G protein? (1 point)
anchor it to membrane

27. Most forms of retinitis pigmentosa which affect the gene for rod rhodopsin do not lead to night blindness until life is well underway (teenageers or young adults). (a) Why (genetically) is this the case and (b) what does this say about the mutant gene product? (2 points)
(a) autosomal dominant (b) mutant gene product has negative affect

28. "Disease" - defect matching (1 point each)

d familial hypocalciuric hypercalcemia a. b subunit of phosphodiesterase
b sevenless b. receptor tyrosine kinase defect
g aniridia c. erythropoietin
h basal cell carcinoma d. G protein coupled receptor
e whooping cough e. Gai
a mouse rd=retinal dystrophy f. homology to steroid hydroxylase
i antennapedia g. homologous to Drosophila eyeless
c anemia h. homologue of Drosophila patched
f Dwarf (tomato) i. homeotic gene

29. How much transducin is there in a rod relative to rhodopsin? (1 point)
there's about 10 times as much rhodopsin

30. (a) How big is a homeobox and (2) what kind of molecule is it on? (2 points)
(a) 183 bp (b) DNA

31. What hedgehog domain is used for (a) long-range vs (b) short-range signalling? (2 points)
(a) The N terminal portion (b) The N-terminal domain

32. What type of molecule is the blue light receptor for phototropism? (1 point)
flavoprotein

33. To what small molecule does vesicular Rab3A bind? (1 point)
GTP or GDP


34. (a) What molecule is the pheromone for aggergation in the slime mold and (b) what kind of molecule is its receptor? (2 points)
(a) cAMP (b) 7TD protein

35. Why would DNA of apototic cells look like a ladder if run out on a gel? (1 point)
DNA gets chopped in nucleosome lengths

36. What is the difference between "lateral" and "inductive" specification in development? (2 points)
if cells are initially non-equivalent or equivalent respectively

37. Describe the subunit structure of the phosphodiesterase in vertebrate rods. (1 point)
alpha beta gamma gamma

38. In what way is the ethylene receptor reminiscent of signalling in bacteria? (1 point)
histidine kinase

39. What are the two states of phytochrome? (2 points)
red and far red absorbing

40. (a) Chemically what kind of molecule is Raf and (b) what is it's component structure? (2 points)
protein regulatory and catalytic domains

41. (a) What molecule is the elongation factor EF-Tu most like and (b) what does it elongate? (2 points)
ras, peptide chain

42. What do phorbol esters do? (1 point)
stimulate PKC

43. Diacylglydcerol kinase is the first step in the regeneration of what signalling precursor? (1 point)
PIP2

44. Where is OBP (odorant binding protein) located? (1 point)
in the mucus outside the cell



45. The "American" vs "European" plans are used to distinguish developmental mechanisms. (a) Which applies to the fly eye and (b) why? (2 points)
(a) American (b) because cells are not necessarily clonally related

46. For what did Earl Sutherland win the Nobel Prize for Physiology and Medicine in 1971? (1 point)
hormone mechanisms (cAMP, father of signalling)

47. What sorts of post-translational modifications are ther on the C-terminus of the 7 transmembrane domain receptor? (2 points)
palmitate on cysteines for anchoring
phosphorylated by kinase (like RK)

48 Why is the ENOD (early nodulation) gene (for the peptide signal) really odd relative to the animal examples of peptide signalling) (1 point)
small open reading frame, peptide not cleaved from larger precursor

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