Sample Exam III

<body topmargin=0 leftmargin=0 marginheight=0 marginwidth=0> <table cellpadding=0 cellspacing=0 border=0><tr> <td valign="top" colspan=2 height=90 BGCOLOR="#006699" TEXT="#080000" bgproperties="fixed" background="109285a1erlcgo.gif"> <div> <FONT SIZE="5" COLOR="#FFCC66" FACE="Arial" ><B>Human Genetics</B></FONT><B>     |     </B><A HREF="index.htm" TARGET="_top" TITLE="Human Genetics"><U><B>home</B></U></A></div> <div> <A HREF="id36.htm" TARGET="_top" TITLE="Syllabus"><U>Syllabus</U></A>   |   <A HREF="id82.htm" TARGET="_top" TITLE="Journal Club Days"><U>Journal Club Days</U></A>   |   <A HREF="id27.htm" TARGET="_top" TITLE="Journal Guidelines"><U>Journal Guidelines</U></A>   |   <A HREF="id38.htm" TARGET="_top" TITLE="Journal Club Guidelines"><U>Journal Club Guidelines</U></A>   |   <A HREF="id90.htm" TARGET="_top" TITLE="Genetics Education Model Project"><U>Genetics Education Model Project</U></A>   |   <A HREF="id53.htm" TARGET="_top" TITLE="Recessive Inheritance Model"><U>Recessive Inheritance Model</U></A>   |   <A HREF="id98.htm" TARGET="_top" TITLE="figures"><U>figures</U></A>   |   <A HREF="id52.htm" TARGET="_top" TITLE="Sample Exam I"><U>Sample Exam I</U></A>   |   <A HREF="id62.htm" TARGET="_top" TITLE="Sample Exam II"><U>Sample Exam II</U></A>   |   <B>Sample Exam III</B>   |   <A HREF="id78.htm" TARGET="_top" TITLE="Sample Exam IV"><U>Sample Exam IV</U></A></div> <div> </div> </td> </tr><tr> <td valign="top" width=210 BGCOLOR="#FFCC66" TEXT="#080000" background="108d2c00dkelyh.gif"> <bR> </td> <td valign="top" height=390 BGCOLOR="#FFFFFF" TEXT="#080000"> <div> <I>Sample Exam III</I></div> <div> <B>Short answer questions</B></div> <div> 1. What are two different classes of proto-oncogenes?  Explain how mutations in these classes promote uncontrolled cell growth.</div> <bR> <div> 2. What is heteroplasmy?  How can this idea be used to explain the variable expression in affected siblings born to the same parents?  </div> <bR> <div> 3. Human heart disease has characteristics which fit both the polygenic model of inheritance and the threshold model of inheritance.  Explain the basic idea of each inheritance model noting at least two differences between the models. </div> <bR> <div> 4.  What is the two-hit model of tumor formation?  Using this model, explain why patients with the inherited form of retinoblastoma usually develop tumors in both eyes, whereas only one of the eyes becomes tumorous in the spontaneous form of the disease.  </div> <bR> <div> 5. An extremely rare event can occur in which one sperm fertilizes the mature egg and another sperm fertilizes the second polar body.  This event yields an unusual pair of twins.  What are two sources of genetic diversity for these twins assuming that no crossovers have occurred?  Please explain how each diversity is generated.</div> <bR> <div> <B>Full-length questions </B></div> <div> 1. Height in humans depends on the additive action of genes. Assume that this trait is controlled by the four loci D, E, F, and G and that environmental effects are minimal.</div> <bR> <div> a. Can two individuals of moderate height produce offspring that are much taller or shorter than either parent?  Please explain.</div> <div> b. If an individual with the minimum height specified by these genes marries an individual of intermediate or moderate height, will any of their children be taller than the tall parent?  Why or why not?</div> <bR> <div> 2. In the following table, average <U>differences</U> of height and weight between monozygotic (identical) twins (reared together and apart), dizygotic (fraternal) twins, and siblings are compared.  Draw as many conclusions as you can concerning the effects of genetics and the environment in influencing these human traits.</div> <bR> <div> <TABLE BORDER="2" CELLPADDING="2" CELLSPACING="1" WIDTH="395" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="BOX" RULES="ALL" ALIGN="BOTTOM" HSPACE="0" VSPACE="0" > <tR> <tD VALIGN=TOP HEIGHT= 19 WIDTH="71"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="19" ALIGN="bottom" WIDTH="71" HSPACE="0" VSPACE="0"></tD> <tD VALIGN=TOP WIDTH="71"><div> MZ</div> </tD> <tD VALIGN=TOP WIDTH="71"><div> MZ</div> </tD> <tD VALIGN=TOP WIDTH="71"><div> DZ</div> </tD> <tD VALIGN=TOP><NOBR><div> Siblings</div> </NOBR></tD> </tR> <tR> <tD VALIGN=TOP HEIGHT= 38 WIDTH="71"><div> <B>Trait</B></div> </tD> <tD VALIGN=TOP WIDTH="71"><div> reared together</div> </tD> <tD VALIGN=TOP WIDTH="71"><div> reared apart</div> </tD> <tD VALIGN=TOP WIDTH="71"><div> reared together</div> </tD> <tD VALIGN=TOP WIDTH="71"><div> reared together</div> </tD> </tR> <tR> <tD VALIGN=TOP HEIGHT= 39 WIDTH="71"><div> <B>height (cm)</B></div> </tD> <tD VALIGN=TOP WIDTH="71"><div> 1.7</div> </tD> <tD VALIGN=TOP WIDTH="71"><div> 1.8</div> </tD> <tD VALIGN=TOP WIDTH="71"><div> 4.4</div> </tD> <tD VALIGN=TOP WIDTH="71"><div> 4.5</div> </tD> </tR> <tR> <tD VALIGN=TOP HEIGHT= 39 WIDTH="71"><div> <B>weight (kg)</B></div> </tD> <tD VALIGN=TOP WIDTH="71"><div> 1.9</div> </tD> <tD VALIGN=TOP WIDTH="71"><div> 4.5</div> </tD> <tD VALIGN=TOP WIDTH="71"><div> 4.5</div> </tD> <tD VALIGN=TOP WIDTH="71"><div> 4.7</div> </tD> </tR> </TABLE></div> <bR> <div> 3. In order for a tumor to metastasize, the cells must acquire a large number of new characteristics.  </div> <div> a. What are four characteristics that the cancer cells must gain to form a metastasis?</div> <div> b. To acquire these new characteristics, genetic alterations must be acquired.  Describe at least two mechanisms that can generate this increasing genetic instability?</div> <bR> <div> 4. Since the Chernobyl nuclear reactor accident, several normal looking couples have married and produced children.  One of these couples has produced children with adult onset muscle degeneration.  You suspect that this mutation is mitochondrially-derived or inherited in a nuclear-derived dominant fashion.  Design an experiment or experimental protocol to determine the mode of inheritance and eliminate the other possibility.</div> <bR> <div> 5. You are given the task of investigating a new gene that may be involved in cancer and cell cycle control.  You have been given the normal (non-tumorigenic) version and a known tumorigenic (tumor-promoting) mutant version of a tumor suppressor gene.  You find another allele of this gene in a breast cancer cell.  You want to determine whether this allele represents a polymorphism or another tumorigenic mutant allele of the gene.  To do this, you transfect cells that are <B>already mutant for this gene</B> with no DNA, the normal gene, the tumorigenic gene, or the suspected tumorigenic gene and monitor whether the cells continue to undergo cell division indefinitely (+) or not (-).  </div> <bR> <div> a.      Fill in the following table to identify your expectations.</div> <bR> <DIV ALIGN="LEFT"></DIV> <div> <TABLE BORDER="2" CELLPADDING="1" CELLSPACING="1" WIDTH="676" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="BOX" RULES="ALL" ALIGN="BOTTOM" HSPACE="0" VSPACE="0" > <tR> <tD VALIGN=TOP HEIGHT= 58 ><NOBR><div> <B>(transfection into </B></div> <div> <B>MUTANT cells)</B></div> </NOBR></tD> <tD VALIGN=TOP WIDTH="118"><bR> <div> <B>+ no DNA</B></div> </tD> <tD VALIGN=TOP><NOBR><div> <B>+ normal tumor</B></div> <div> <B>suppressor</B></div> <div> <B>gene</B></div> </NOBR></tD> <tD VALIGN=TOP WIDTH="131"><div> <B>+ tumorigenic tumor suppressor gene</B></div> </tD> <tD VALIGN=TOP WIDTH="131"><div> <B>+ suspected tumorigenic mutant gene</B></div> </tD> </tR> <tR> <tD VALIGN=TOP HEIGHT= 77 WIDTH="137"><div> I expect these results if the suspected mutation is <B>tumorigenic</B>.</div> </tD> <tD VALIGN=TOP WIDTH="118"><bR> <div> <B>+</B></div> </tD> <tD VALIGN=TOP WIDTH="129"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="77" ALIGN="bottom" WIDTH="129" HSPACE="0" VSPACE="0"></tD> <tD VALIGN=TOP WIDTH="131"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="77" ALIGN="bottom" WIDTH="131" HSPACE="0" VSPACE="0"></tD> <tD VALIGN=TOP WIDTH="131"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="77" ALIGN="bottom" WIDTH="131" HSPACE="0" VSPACE="0"></tD> </tR> <tR> <tD VALIGN=TOP HEIGHT= 97 WIDTH="137"><div> I expect these results if the suspected mutation is a <B>polymorphism</B>.</div> </tD> <tD VALIGN=TOP WIDTH="118"><bR> <div> <B>+</B></div> </tD> <tD VALIGN=TOP WIDTH="129"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="97" ALIGN="bottom" WIDTH="129" HSPACE="0" VSPACE="0"></tD> <tD VALIGN=TOP WIDTH="131"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="97" ALIGN="bottom" WIDTH="131" HSPACE="0" VSPACE="0"></tD> <tD VALIGN=TOP WIDTH="131"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="97" ALIGN="bottom" WIDTH="131" HSPACE="0" VSPACE="0"></tD> </tR> </TABLE></div> <div> Explain your reasoning briefly.</div> <div> b.      What would be the consequence of transfecting the tumorigenic version of this gene into a  normal cell?  Please explain.</div> <bR> <bR> </td> </tr></table></body>