1) What are the basic subunits in actin
filaments? In microtubules? (3pt)
2) What organelles in the biosynthetic pathway overlap with those in the secretory pathway? (4pt)
3) Name the 2 main components of the ECM? (2pt)
4) Why is it important that the amount endocytosis in a cell is balanced by the amount of exocytosis? (3pt)
5) What is paracrine signaling? (2pt)
6) When performing an experiment what is a 'mock-treatment'? Why is it performed? (4pt)
7) How are hormone receptors similar to ECM receptors? How are they different? (5pt)
8) Early experiments tried to determine whether cellular components moved between organelles using specialized tubes or using vesicles. Describe an experiment that supports transport in vesicles. (6pt)
9) Why did Choquet, Felsenfeld and Sheetz conclude that reinforcement includes a "biochemical step"? (Be sure to include a definition of reinforcement) (5pt)
10) Immobile cilia syndrome causes chronic respiratory problems because the cytoskeletal elements within the cilia do not 'slide' next to each other.
a) Describe the structure of a basic filament of this type of cytoskeletal element. (How is it organized? What, in general, does it look like?) (4pt)
b) Why would having 'immobile cilia' cause respiratory problems? (3pt)
11) Describe the role of nucleotides in
the polymerization of microtubules and in the function of cytoplasmic kinesin.
12) Cancer cells often show decreased expression of fibronectin. Is this finding consistent with the fact that these cells can 'metastasize' (move out of their 'original organ')? Why or why not? (5pt)
13) What are the 3 general steps in vesicular transport between a 'donor' and an 'acceptor' membrane? (3pt)
14) In which step(s) in vesicular transport did Barroso, Nelson and Sztul propose TAP was functioning? Is/Are these the same step(s) in which rab proteins are thought to function? (Explain) (4pt)
15) BONUS (Answer in one or two sentences--be very brief!) Who just won the Nobel prize for medicine? For what finding/hypothesis did they win it?
Section II questions 1-12 (43pt
All of the questions in this section relate to the experimental scenario developed below. Be sure to answer the questions in light of the information you have been given. (Also, as always, answers must be in complete sentences.)
You are a post-doctoral fellow interested in understanding cellular communication. You join laboratory that uses yeast mating as a model system. Since you have only read about yeast but have never worked with them before, you decide to brush up on the basics. You obtain 2 strains of brewer's yeast (listed below) and decide to demonstrate complementation between the auxotrophic strains.
|Strain 1: a, -leu||Strain2: a, -lys|
1) What is the scientific (latin) name
for these yeast? (genus, species) (2pt)
2) Define the term auxotrophic. (3pt)
3) Explain what it means to say that 2 strains complement each other. (3pt)
4) Provide an overview of your test for complementation. For full credit your description does not need to include details like volumes but must include how complementation was detected and the positive and negative controls that were used. (7pt)
After working in the lab for 1 year, and through much arduous work, you isolate a mutant strain which contains an overactive form of a known molecular motor. The defect results in increased vesicular traffic to the shmoo tip and an increase in mating efficiency.
5) Hypothesize how this type of change
in vesicular traffic might cause an increase in mating efficiency. (6pt)
6) Name the molecular motor that is involved in yeast vesicular traffic. (2pt)
7) On what cytoskeletal component does the motor named in #6 travel? (2pt)
You collect a great deal of data that characterizes your mutant yeast strain and submit a paper to the journal Cell. One of scientists reviewing your paper is skeptical that the cytoskeletal component you named in #7 is actually involved in this trafficking event. (He thinks a different type of cytoskeletal element is involved.) To prove your point you provide the data from a mating efficiency experiment preformed between a 'normal' strain and your strain. Each mating was identical except that your mutant strain had been treated with drugs that effect the stability of cytoskeletal elements. The data is summarized in the table below.
After adding this table, you resubmit the paper. The reviewer is convinced and the article is accepted. (Your boss takes you out to dinner)
8) Is the peer-review process important
to the progress of science? (Why or why not?) (5pt)
9) In the mating efficiency experiment described above what were the 2 drugs you used to effect the stability of cytoskeletal elements? (3pt)
10) This experiment proved to the reviewer that cytoskeletal component you named, and not another one, was involved traffic to the shmoo. Why? (5pt)
11) The head of your lab tells you that it is time to write a grant because the grant funding your project will run out of money in one year. He asks you to get application forms from funding sources. Name 2 places from which you could get applications. (2pt)
12) To be in this type of a research position what level of academic degree do you need to hold? (not what field, what level) (1pt)