BCHM2072/2972 Semester 2, 2005
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HOW TO ENSURE YOUR MCQ
ANSWERS ARE COUNTED
MCQ answer sheets are fed through a scanner and read
in comparison to a blank answer sheet. The scanner can’t
cope with any change in the configuration of the answer
sheet, whiteout, crossed-out answers, etc
Here are some tips for ensuring a safe passage for your
answer sheet through the scanner:
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DO use the answer sheet provided for this particular assignment (ie
MCQs 1-15). Sheets for other assignments won’t be read by the scanner
DON’T photocopy an answer sheet. Photocopied sheets are invariably
changed in size and won’t be read by the scanner
DO include your NAME and PRAC GROUP at the top (so that we can
locate you if necessary)
DO fill in your FULL SID (ALL 9 numbers)
DO use a DARK pen/pencil and COMPLETELY fill in your choice
DON’T use whiteout. If you make a mistake, use a fresh sheet
DO put only ONE answer for each question
DON’T cross out or write over mistakes on a sheet. Use a fresh one
DON’T staple anything to the sheet
DON’T curl over the corners of the sheet
DON’T fold or crease the sheet
IF YOU DON’T ATTEND TO ALL OF THESE THINGS,
YOUR DETAILS AND EACH ANSWER WILL HAVE TO
BE FILLED IN MANUALLY – this will delay the return of
marks
BCHM2072/2972 Semester 2, 2005
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ASSIGNMENT 4, WEEK 9
This assignment is due in the box at the front of the lecture theatre by no later
than 10.10 am on Wednesday 5th October. Late assignments, assignments not
answered on the grid provided, or assignments not covered by a plagiarism
statement (universal or individual) will not be marked. Remember, submission of
assignments is entirely voluntary. Enter your SID and answer all questions by
filling in the relevant circles on the grid provided. Grids can be collected from
under the green notice boards in the BCHM2 labs.
1.
Which of the following statements concerning protein folding is incorrect?
A.
B.
C.
D.
E.
2.
Glucose units are added and removed from proteins in the ER. What is the
function of this process?
A.
B.
C.
D.
E.
3.
The ER is a reducing environment so disulphide bonds readily
form, unlike the oxidizing environment of the cytoplasm
Proteins destined for secretion are folded in the ER and released
via the Golgi Apparatus
Proteins folded in the ER often have sugars attached which are
first assembled on dolichol
Protein disulphide isomerase (PDI) catalyses the breaking and
reforming of disulphide bonds on proteins folded in the ER
Proteins destined for the nucleus are translated and folded in the
cytoplasm
To tag proteins for export to the cell surface
To increase the solubility of cell surface proteins
To provide unique antigen determinants for cell surface markers
As an indicator of the extent of folding or how complete the
folding process is
To prevent aggregation and precipitation in the ER
Which of the following statements about signal recognition particles (SRPs)
is incorrect? A SRP:
A.
B.
C.
D.
E.
Contains RNA and protein
Docks with SNARE proteins on the inner face of the outer cell
membrane to facilitate the secretion of proteins from cells
Docks with a receptor on the surface of the ER membrane
Enables translation of proteins into the ER
Binds to localization signals on the N terminal of the emerging
polypeptide chain
BCHM2072/2972 Semester 2, 2005
4.
A mutation in v-SNARE proteins would result in:
A.
B.
C.
D.
E.
5.
B.
C.
D.
E.
Soluble proteins destined for export often have sugars added
post translationally
Chaperones such as BiP proteins prevent protein aggregation
during folding
Proteins destined for export from the cell have a localization
signal contained in the mRNA sequence at the 5’ untranslated
region which enables a SRP to bind and direct translation into
the ER
Proteins destined for export are ferried to the inner face of the
cell membrane in vesicles which bud off from the Golgi
Apparatus
Secretion involves the hydrolysis of ATP catalysed by an NSF
protein
Which of the following methods of anchoring proteins to the outer cell
membrane requires functional translocons?
A.
B.
C.
D.
E.
7.
Secretion of proteins normally found embedded on the cell
surface
An inability to bind to phosphotyrosines
Aggregated proteins which would precipitate in the lumen
Defective glycosylation of proteins in the lumen
An inability to fuse vesicles with the cell membrane
Which of the following is not a step in the secretion of proteins?
A.
6.
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Alpha helical protein domains containing hydrophobic residues
Disulfide bond anchors
Palmitoyl anchors
GPI (glycosylphosphatidylinositol) anchors
Ionic interactions with phospholipid head groups
What is the role of –SH2 domains on proteins?
A.
B.
C.
D.
E.
To phosphorylate specific tyrosine residues on receptor proteins
To slowly hydrolyse GTP to GDP
To exchange GDP for GTP
To bind to phosphotyrosine, but not tyrosine residues
To catalyse the formation of disulfide bonds from SH groups
BCHM2072/2972 Semester 2, 2005
8.
Which of the following does not occur during the activation of G-coupled
protein receptors?
A.
B.
C.
D.
E.
9.
D.
E.
Autophosphorylation of a tyrosine kinase bound to the receptor
An influx of Ca2+ through activation of a ligand-gated ion channel
Displacement of GDP by GTP on a G protein bound to the
receptor
Dissociation of the receptor from a dimer to a monomer form
Inhibition of intra-cellular adenyl cyclase
A common structural theme in the 7-TMS family of receptors is:
A.
B.
C.
D.
E.
11.
The dissociation of the alpha subunit from the beta/gamma dimer
during activation
The displacement of a GDP with a GTP
The phosphorylation of tyrosines within the receptor upon ligand
binding
The dissociation of the G protein trimer from the 7-TMS receptor
upon ligand binding
The slow hydrolysis of GTP to restore the receptor to its inactive
form
Binding of a cytokine to a cytokine receptor would be generally expected to
lead to:
A.
B.
C.
10.
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They all contain seven strands of -sheet which span the cell
membrane
They all mediate signal transduction through G-protein coupled
events
They all contain protein tyrosine kinase domains at their C-termini
They are all GPI-anchored proteins
None of them are glycoproteins
Which of the following statements about the JAK-STAT signalling pathway
is correct?
A.
B.
C.
D.
E.
Activation of JAK kinases allows them to enter the nucleus and
phosphorylate STAT proteins
JAK kinases use GTP to phosphorylate small GTP-binding proteins
such as Ras
Dephosphorylation of STAT proteins allows them to dimerise
through their SH2 domains
JAK-dependent phosphorylation of protein kinase C leads to
inhibition of phospholipase C
Up-regulation of SOCS protein expression would be expected to
down-regulate STAT activity
BCHM2072/2972 Semester 2, 2005
12.
Which of the following statements about activation of protein kinase C is
correct?
A.
B.
C.
D.
E.
13.
B.
C.
D.
E.
Lead to dissociation of receptor dimers into their active monomer
forms
Lead to inhibition of export of proteins from the nucleus
Lead to the inhibition of protein kinase C because of increased
levels of intra-cellular Ca 2+
Lead to production of both phosphotyrosine and phosphoserinemodified proteins
Have no effect in cells which do not express the NFKB transcription
factor
The NF-KB transcription factor:
A.
B.
C.
D.
E.
15.
An influx of Ca2+ from the extra-cellular medium leads to conversion
of protein kinase C into its active form
Protein kinase C could be activated via both growth factor and 7-TMS
receptor signalling
Protein kinase C becomes activated after dissociation of its
regulatory subunits
Phospholipase C hydrolyses phospholipids in the ER membrane,
leading to Ca2+ release
Diacyl glycerol is phosphorylated and becomes incorporated into
the cell membrane
In general, binding of growth factors to their receptors might be expected
to:
A.
14.
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Requires removal of inhibitory phosphate groups in order to
become active
Is an example of a steroid hormone receptor
Is activated by protein kinase A
Is unusual because is does not contain a signal peptide
Is normally present in the cytoplasm
Which one of the following would indicate involvement of calcium ions in
the signalling mechanism of a receptor?
A.
B.
C.
D.
E.
Activation of Ras and the MAP kinase cascade
Cytoplasmic protein kinase C in cells in which the receptor is
expressed
Phosphotyrosine binding sites for phospholipase C on the
activated receptor
Receptor-stimulated synthesis of cAMP
Receptor-stimulated activation of a heterotrimeric G protein