Cell Biology

Biology 308: Review 2                                  November 2000



The review is due Monday November 13, 2000 at 3:00pm


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 does not begin until you read any question within this packet.


Any questions about the review should be directed to me at kabernd@davidson.edu, 894-2889 (o), or XXX (h). Any calls to my home must occur before 9:00pm.



Name: ____________________________________




Signature: ­­­­­­­_________________________________

My signature indicates that I have completed this review following the Honor Code.


This review was completed in ________hours



Question 1 (parts 1-4, 19pt)

The unpredictable and cyclic nature of Bipolar disorder makes it both fascinating and frustrating to study. Initially efforts could only focus on characterizing symptoms. More recently theories have been proposed to explain the molecular basis of this disorder.


1)    Provide a well-labeled diagram of a neuron indicating its major structural parts. (6pt)

2)    What is the Catecholamine theory of affective disorder? (4pt)

3)    What is an inhibitory response at a synapse Include the role of ions in this process. (3pt)

4)    Would neurotransmitters and neurotransmitter receptors be predicted to contain ER signal sequences? (why or why not) (6pt)

Bonus: Suicide is the second highest cause of death of college students. What ranks first as a cause of death on college campuses? (1pt)


Question 2 (parts 1-4; 15pt total)

A friend from another school calls you. Their Cell Bio lab is also studying mating (using brewer’s yeast) and they have performed a number of experiments but the lab manual isn’t clear and he doesn’t know how to interpret his results. He has to finish his project and write a lab report. He is beginning to panic and needs your help.


They have 3 yeast strains: KKB1 wt strain (a, -his); KKB2 wt strain (alpha, -trp);

RGN 1  nonmating strain (a –his)


A complementation test between KKB2 and RGN1 resulted in colony growth on –HIS, YEPD, -TRP, and (-HIS,-TRP) plates.


They then performed serial dilution of log phase cultures of KKB1 and RGN1. They mixed equal amounts of each dilution and undiluted KKB2 cells, plated 100ul of the mixture on the plates indicated and counted colonies after 2 days of growth at 30°C. He emails you a table of the mixtures and the number of colonies seen in each growth condition.







































His report needs an introduction including background information on yeast and his professor is a stickler for Latin names. When your friend was working in lab he accidentally spilled his Nalgene water bottle on his notebook and now he can’t read the introductory information that tells him about his yeast and yeast mating.


1)    What is the Latin name of the organism he is studying? (3pt)

2)    If he had followed all laboratory safety rules he would know the background material. What safety rule did he break? (2pt)

3)    What is the mating efficiency of RGN1? (show calculations—hand written is ok) (5pt)

4)    They were told that RGN1 is a mating mutant. Are the results of the complementation test and the mating efficiency test consistent with that description? (Be sure to mention the results of both tests in your answer) (5pt)



Question 3 (parts 1- 14; 61 points)

You have identified a free-swimming algae that regulates its internal temperature by concentrating or dispersing pigment filled vesicles. Enthralled, you decide to study these vesicles and their movement. Early research indicates that the vesicles are derived from the trans Golgi network (TGN) and travel along microtubules. When the algae are in a warm environment the pigment vesicles (abbreviated PV) are moved to the center of the algae. When the temperature is cooler the PV are moved to just under the plasma membrane so that they can help to capture solar energy. The motors appear to be the same as those used in mammalian systems.


You set up an in vitro assay to study the motor involved in PV movement

1)    Microtubules are polymers. What is the basic unit of unit of this polymer? (3pt)

2)    Name the compartments of the cell where microtubule genes are transcribed and the resulting message is translated. (3pt)

3)    In mammals what are the minimal components needed to study (+) end directed movement in an in vitro assay? (You may assume you have access to purified proteins) (5pt)

4)    You decide it would be prudent to add a drug to stabilize the microtubules in your algae PV movement assay. What drug do you add? (2pt)

Bonus: what drug could you add to destabilize microtubules? (2pt)

5)    Briefly describe how a microtubule stabilizing drug would effect mating in yeast. (3pt)

6)    Microtubules are not static structures. Discuss the role of nucleotides in the process of dynamic instability. (4pt)


These algae have a unique mechanism for dealing with extremes in heat. Since the dark pigment helps retain heat, under extreme conditions the algae secrete the pigment and thus turn a much ‘cooler’ clear color. The release of the pigment covers the cells with a brown color that is then washed away. In lakes containing large populations of these algae, this can cover the surface of the lake with a distinctive ‘brown ooze’.


7)    Pigment release is an example of what type of exocytosis? In your answer provide a definition of that type of exocytosis and an example of that type of exocytosis from mammalian cells. (5pt)

8)    Is it reasonable to predict that TAP would have a role in the exocytosis of pigment? (why or why not) (4pt)


You are interested in the interactions that allow a particular motor to interact with a specific vesicle. A current hypothesis states that the vesicle must contain a protein that acts as a molecular marker or ‘ZIP code’. You think that you have identified such a protein in the membrane of the pigment vesicle. You name the protein Vrom (for vesicle receptor onto motor). As seen in the diagram the cytoplasmic portion of Vrom is predicted to interact with a motor protein. You begin gathering data about Vrom, its synthesis, localization and function.





9)    Name 2 agencies you could apply to for grant money to support this research project. (3pt)

10) Transcription of the gene encoding vrom reveals no surprises. However its processing is slightly unusual. Vrom mRNA has a poly(A )tail that is very short. What is a poly(A) tail and what consequences might result from an mRNA having a very short one? (5pt)

11) Analysis of the 5’ end of the mRNA shows that it contains two start codons. How does the cell know which one to use to begin translation and what cellular components are necessary to form the initiation complex? (5pt) 

12) As indicated, Vrom is part of a pigment vesicle membrane. How could you determine if its translocation occurred using an SRP-mediated or a Sec mediated pathway? (Be sure to describe the 2 translocation pathways in your answer) (9pt)

13) Name all of the cellular compartments that the Vrom protein will pass through before it is incorporated into a pigment vesicle? (4pt)


Data suggests that the last 6 amino acids of Vrom (KRLVDE) are important for the interaction between the vesicle and their motor protein.


14) How can you demonstrate that the KRLVDE region is both necessary and sufficient for vesicle/motor protein interaction? (6pt) (theoretical explanation is enough, experimental design is not needed)


Question 4: (1 part 5pt)


Every once and a while a student will approach me saying “Dr Bernd, if you had only asked X. I know all about that but you didn’t ask me”. Here is your chance. Write and answer your own short answer question. It must relate to a topic we have covered in this section and cannot repeat any of the questions that appear above. My advice—keep it simple and straight forward and don’t ask yourself to write a book. (5pt)