These instructions include changes, please read and follow them.

As in previous reviews, your answers must be typed but any figures may be hand-drawn. In order to identify trends and standardize grading I always grade every person's answer for particular question before moving on to the next one. Please begin sections on separate pages and place extra spaces between questions. Include both your typed and signed name on the top of the first page and your initials and the page number on every additional page. Your signature indicates that you have completed this exam following the honor code. Carefully read each question and limit your answers to the questions asked. When appropriate provide the logic behind your answer. The review should not take more than 2 hours even if you are a bad typist and as always the question sheets are yours to keep.

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) or phone 892-2889 (o) during ëbusinessí hours. I WILL NOT be in to check my email over the weekend, my home # is XXX-XXXX. Please remember that I no longer keep ëstudent hoursí; use my home number only before 9pm.

Section I -- Very Short Answers

Each question in this section should be answered with one word or a short phrase (26pt total)

1) In one or two words what happens to the signal during an enzyme cascade?
2) Name three places a cell degrades proteins
3) SAR is an example of what type of intercellular signaling?
4) Name a toxin that inhibits a trimeric G protein and list the G protein
5) Name three 2nd messenger molecules
6) Name the three classes of cell surface receptor proteins

Choose the word or words that correctly completes the each of the following phrases. Each word is used at least once. Words can be used more than once.

7) __________ involve(s) signaling over long distance.
8) The intercellular signaling molecule travels only a very short distance in
    __________ signaling.
9) __________ provide(s) transient connections between cells that allow
    transfer of small molecules.
10) Cell-to-cell communication requiring touch can be mediated by
    __________.
11) The connection(s) between hormone and 2nd messenger is/are provided
    by __________.
12) The diffusion of local signals can be restricted by __________.
13) During __________ signaling one cell can both 'signal' and 'receive'.
14) A GPCR is an example of a(n) __________ protein.

Section II

Question 1 parts A-F ( 32 pt total)

Yeast mating requires both inter- and intra-cellular signaling. The intercellular signal received by a mating type a cell is the pheromone a factor. In a normal (wild type) cell, a factor is bound by a G protein coupled receptor which acts through a Gs trimeric G protein to cause arrested growth and activates the mating response (shmooing). Yeast mutants in which the genes that encode either the a factor-receptor or components of the trimeric G protein have been deleted have been constructed. These strains show characteristic phenotypes when grown in the absence or in the presence of a factor (listed below). Deletion (removal) of any of these genes from the genome makes the strain unable mate so they are all called sterile mutants. (side note­these data are all ërealí --it actually happens this way)
 

Mutation in strain	Growth minus a factor	Phenotype plus a factor
None (wild type)	budding	arrested growth, shmooing
Receptor deleted	budding	budding, sterile
a subunit deleted	arrested growth	arrested growth, sterile
b subunit deleted	budding	budding, sterile
g subunit deleted	budding	budding, sterile
both a and b deleted	budding	budding, sterile
both a and g deleted	budding	budding, sterile

Question 2 parts A-D ( 11 pt total)

As a world famous endocrinologist you are characterizing a newly discovered signaling substance called ëhormoniní. You have set up a system where you grow cells in a petri dish and determine how fast they multiply under different conditions. The data you have accumulated using Type 1 cells are listed below

Untreated cells--- cells double every 12 hours
Cells incubated with hormonin--- cells double every 3 hours
Cells incubated with protease--- cells double every 12 hours
Cells incubated with protease
    protease washed away then
    cells incubated with hormonin--- cells double every 3 hours

A) Is hormonin a mitogen? (explain) (4pt)
B) With what type of receptor does hormonin interact? (explain) (3pt)
C) You decide to characterize hormoninís effect on a different cell-type
(cleverly called Type 2 cells). You find that the number of Type 2 cells doubles once every 8 hours when untreated and also doubles once every 8 hours when incubated with hormonin. How can this be? (4pt)

Section III

Short answers (31pt total)

1)To what does the term molecular memory refer? Provide an example of this phenomenon in your answer. 5pt

2)What is ubiquitin a signal for? Provide 2 examples of kinds of proteins that might be targeted for ubiquitination. 4pt

3)List 4 categories of enzyme-linked receptors and provide a brief description of what each one does. 8pt

4)Describe the role of phospholipids in intracellular signaling. 5pt

5)A fibroblast cell line has been genetically engineered so that it expresses both wildtype b-adrenergic receptor and a mutant form of b-adrenergic receptor that can bind ligand but does not contain the cytoplasmic C-terminal ëactivation domainí. If adrenaline is added to the media do you see activation of its intracellular enzyme cascade? Why or why not? 5pt

6) What is the 'N-end rule' 4pt