This review is DUE at 10:30am, Monday, October 26, 1998.

The text of your answers must be typed but any figures may be hand-drawn

The top of the first page of your answers must include both your typed and signed name. Your signature indicates that you have completed this exam following the honor code. The top of each additional page should only contain your initials and the page number. You do not need to turn in the question sheets. This review is not timed. That said it was designed to be completed in one hour and, with typing, should not take more than two.

The review packet contains 5 pages and 3 sections. When a scenario is provided and multiple questions are asked all questions within that part are loosely related. Always briefly provide the logic behind your answer, except when specifically asked for single word answers. In all cases brevity is encouraged.

Once you have read any question your review period has begun. Until that time you are free to study and discuss all topics relating to this class. After that time I am the only person you may ask questions pertaining to this review.

You can reach me by email kabernd@davidson.edu, 892-2889 (o), or XXX-XXXX (h). Please remember that I no longer keep ëstudent hoursí; use my home number sparingly and only before 9pm. After that time I will not answer your call.

Section 1 ó Very Short Answers

Each question in this section should be answered with a list or short phrase (25pt total)

1) Name the 3 types of cytoskeletal filaments
2) Name two organelles that are part of the secretory pathway.
3) What is endocytosis?
4) List the 3 steps in cell movement.
5) Name 1 drug that stabilizes a cytoskeletal filament and list the filament it effects
6) The extracellular matrix provides protection from what 2 forces or pressures?

Choose the word or words that correctly complete each of the following phrases. All words are used at least one time.

7) ____________ is/are marker proteins for lysosomes.
8) Coatomer coated vesicles are involved in _______________.
9) ____________ involve(s) non-selective transport of lumenal cargo proteins.
10) ____________ is/are the ë+ end-directedí motor(s) for cytoskeletal filaments.
11) Association with _________ allow(s) vesicles to move on microtubules.
12) ____________ is/are only active at low pH.
Section II

Question 1 Parts A-E (16pt total)

People suffering from Hurlerís disease do not produce a specific enzyme responsible for the breakdown of glycosaminoglycans (GAGs) so they end up with internal accumulations of GAGs. However this deficiency can be overcome in a petri dish. Grow Hurler cells with normal cells and they can ëscavengeí the enzyme from the liquid in the culture and deliver it to the organelle where it normally functions.

A)What is a glycosaminoglycan and where is it normally found? (3pt)
B)The GAG-degrading enzyme belongs to what general class of proteins? (1pt)
C)Describe the transport pathway that the scavenged enzyme follows from the culture
    to the organelle where it functions. Focus on the type(s) of vesicular traffic and
    organelle(s) the enzyme passes through. A short paragraph and/or well-labeled
    diagram can be used. (5pt)
D)In normal cells modifications must be made to the protein sequence of the enzyme
    so that it is correctly targeted to the digestive compartment. What is the
    modification? In which organelle is the modification added? (2pt)
E)pH can play a role in the uptake, targeting, and activity of a protein. Discuss the
    role, if any, that pH plays in the targeting and activity of this GAG-degrading enzyme
    in normal cells and in the scavenging pathway you described above. (5pt)
 

Question 2 Parts A-D (15pt total)

Fibronectin is a large glycoprotein component of the ECM. It contains several binding sites, one of which interacts with fibronectin receptors on the cell surface.

Fibronectin will stick to plastic surfaces and therefore can be used in a binding assay to determine which parts of fibronectin are recognized by the hypothetical matrix receptor named ëBindití. In this assay plastic petri dishes are coated with fibronectin. A suspension of fibroblasts is added and allowed to incubate for 30 minutes. Finally the dishes are washed and the number of cells that remain stuck are counted using a microscope. If this process is performed without the fibronectin coating, no cells stick. If the fibronectin coating is present a maximum of 80 of cells stick (Maximum of 80% of cells bind to fibronectin)

You have previously narrowed down the region Bindit binds to 6 amino acids within the N-terminus of fibronectin (the residues GKGESP). You decide to perform competition experiments to determine which of the residues are necessary. In each of these experiments a synthetic peptide was included in the 30 minute incubation with the fibronectin and cells and the % of cells bound were calculated (see table).
 
 

A) In which general category of ECM components is fibronectin placed? (2pt)
B)What is a competition experiment and how can using it determine the residues
    that Bindit binds? (5pt)
C)From the given data what is the amino acid sequence that Bindit binds? (3pt)
D) The binding of fibronectin to Bindit causes intracellular effects similar to those
    seen after the binding of fibronectin to integrins. You coat a bead with the
    fibronectin peptide that Bindit binds (GKGESP), place that bead on a fibroblast
    and apply restraining force using optical tweezers. Do you see reinforcement
    (explain)? (5pt)

Question 3 Parts A-C (8pt total)

You are given a yeast strain that does not mate. Further experiments show that:

SectionIII Short answers (37pt total)

1) Draw/describe the structure of the myosin-II complex (muscle myosin). Include
    regions defined by protease digestion. Indicate which part(s) is responsible for
    binding cargo, binding the cytoskeleton and generating force. What are other
    types of motor proteins (non-myosin motors)? Compare their function to that of
    myosin-II. (12pt)

2)Since the ECM is just that ó outside of the cell?explain how it can effect
    organization of intracellular components. (7pt)

3)How could the Rothman in vitro assay for vesicular traffic be used to identify
    soluble proteins that are involved in that process? Provide 2 examples of
    components could have been identified in that assay. (10pt)

4)Explain the role of GTP in polymerizing and stabilizing microtubules. (8pt)