Cell
Biology
Biology
308: Review 2 November
2001
There
are two possible due times for this review. A review turned in by Monday
November 12, 2001 at 3:00pm will receive 1.5 bonus points.
All
reviews must be received by 8:30am Tuesday November 13, 2001.
This
is a closed-book, closed-note review. There is no time limit for taking the
review. All answers must be typed. You may use a calculator if
calculations are required. However, the steps behind any calculation must be
included to receive full credit (can be hand-written). Any figures or graphs
may be hand-drawn.
The
questions are yours to keep. This page must be the first page of your answer
packet. Fill out the information at the bottom and attach this page to the ones
containing your answers. The top of each additional page in the packet should
contain only your initials and the page number.
Your
review period begins when you read any question within this packet.
You
can contact me at kabernd@davidson.edu, x2889 (o), or xxxxxxx (h). Any calls to
my home must occur before 9:00pm.
Name:
____________________________________
(print)
Signature:
_________________________________
My
signature indicates that I have completed this review following the Honor Code.
This
review was completed in ________hours
I turned in this
review by 3pm Monday ___ , attended the Animal Phys. lecture ___, the Bioethics
lecture ___, the Chemistry lecture ___
The review
contains 16 questions worth a total of 100 points and 4.5 attendance bonus
points.
Section 1:
X-linked
nonspecific mental retardation is an inherited disease that is cause by
mutations in a protein called Rab GDP dissociation inhibitor a
(Rab GDI a). Rab GDI a is expressed in
the central nervous system and mutations in this protein result in mental
retardation as well as defects in neuronal development.
1) What is the name of the monomeric
subunits found in Rab GDI a? 2pt
2) Given the function indicated by its name,
where in the cell do you predict this protein would be found? (Be sure to
explain your prediction) 4pt
While
researching Rab GDI a you find that it is encoded by a 7500
nucleotide gene called XAP-4 and that the XAP-4 mRNA is 2500 nucleotides in
length.
3) Provide a well-labeled diagram depicting
the regions fond within any gene. (Labeled diagram only. No definitions) 4pt
4) Referring to your diagram as needed,
explain the differences between the XAP-4 gene and the XAP-4 mRNA. (Account for
all regions of a functional mRNA) 5pt
Ca2+
channels are also found in the central nervous system.
5) Where in a neuron are Ca2+
channels found? 3pt
6) What makes neuronal Ca2+
channels open? Why is this opening important for neuronal function? 6pt
7) Compare and contrast the steps required
to go from XAP-4 mRNA and Ca2+ channel mRNA to localized, functional
Rab GDI a and Ca2+ channel proteins. Every detail of every
process should not be included. For example if photosynthesis is involved it is
sufficient to say “The first step in the processing of each of the mRNAs
is photosynthesis in the chloroplast”. DO
include salient information regarding targeting. 10pt
8) According to the SNARE hypothesis what
role do Rab proteins play in cellular transport? 5pt
9) Describe an experiment that would test if
Rab GDI a is involved in transcytotic fusion. Be sure to explain
controls for your experiment. (Details such as incubation times and volumes are
not necessary but be sure to include how you would be able to interpret your
results) 8pt
10) Predict and explain the results for the
experiment described in #9. 5pt
Section 2:
The level of
sexual mating in yeast (yeast fertility) relies on the coordinated action of
many cellular components. While working on your mutant characterization in lab
you decide to ‘play with’ cellular components and determine the
effect on mating.
11) Would each of the following conditions be
predicted to increase, decrease or have no effect on yeast mating efficiency of
otherwise ‘normal’ yeast? Be sure to explain your reasoning. (5pt
each)
a) Treatment of both cell types with taxol.
b) A mutation in each cell type causing G
actin to show an increased rate of ATP hydrolysis.
c) A mutation in each cell type causing
kinesin to show an increased level of ATP hydrolysis.
12) Given a yeast genetics lab, describe the
experimental conditions that would test your predictions for one of the
conditions mentioned in # 11. Include how the results would be
assessed/interpetted. 8pt
Section 3:
Anthrax toxin is
a complex containing three different proteins (PA, LF, and EF) that are
secreted by the bacterium Bacillus anthracis. During an infection the secreted
complex associates with proteins on mammalian cells and is endocytosed. After
internalization anthrax toxin changes shape, PA forms a pore through the
membrane and LF and EF are released into the cytosol. LF and EF then wreak
havoc on the cell as EF disrupts adenylyl cyclase signaling and LF is a
protease that cleaves cytosolic proteins. (This is the true mechanism of
anthrax toxicity.)
13) What are three types of endocytosis
performed by all cell types? (Name them, do not elaborate) 3pt
14) Hypothesize the type of endocytosis
involved in the internalization of anthrax toxin. Be sure to provide support
for a) why you chose this type and b) why you did not chose the other types.
9pt
15) Comparing anthrax toxin to our class
examples of endocytosis, predict the cause of the shape change that activates
PA. 5pt
Cholera toxin is
also internalized by endocytosis. It then follows the retrograde transport
pathway to the ER before exerting its toxic effects.
16) What cellular components would provide
the ‘roads’ and ‘motors’ in the pathway followed by
cholera toxin? (Explain) 8pt