GENETICS - BIOLOGY 97 - Homework due  NOVEMBER 29, 2007     NAME:

    Please try to focus your answers as much as possible.  Aim for brief & complete.  Remember that answers that do not relate to the question may cost credit for errors, but can not earn any credit since they do not answer the question!!  Thus, it is to your advantage to refrain from adding extraneous information.   Please do NOT just copy from a book.  Note that often a book is not answering precisely the question that you are supposed to be addressing!

1.  Complete the chart below on this page (so do it on scratch paper first, & transfer a neat answer to this page to hand in!).  How is this system used to demonstrate trans-dominance?  cis-dominance?  Explain what these terms mean and show how the phenomena can be illustrated  [if necessary, add appropriate experiments to the chart].  Briefly explain the interpretation of these data by noting what can be inferred from each experiment.  Which are controls - and controls for what?  What controls are required to demonstrate each phenomenon? [one way to answer this last part is to list which experiments, as a separate group, could be used to demonstrate each characteristic].  BE CAREFUL - NO CREDIT WILL BE GIVEN FOR REVERSED LINES!

            B-galactosidase        permease            purpose of experiment

            no IPTG   IPTG          no IPTG    IPTG
        
I+O+Z+Y+
I+O+Z+Y-
I+O+Z-Y+
I+O+Z-Y-

I+OcZ+Y+
I+OcZ-Y+
I+OcZ+Y-

I-O+Z+Y+
I-O+Z+Y-

IsO+Z+Y+
IsO+Z-Y+

IsOcZ+Y-

F'I+OcZ+Y-/I+O+Z-Y+
F'I+O+Z+Y-/I+OcZ-Y+
F'I+OcZ+Y-/I+O+Z+Y+

F'IsO+Z+Y-/I+O+Z-Y+
F'I+O+Z+Y-/IsO+Z-Y+
F'IsO+Z+Y-/I+O+Z+Y+

F'I-O+Z+Y-/I+O+Z-Y+
F'I+O+Z+Y-/I-O+Z-Y+

F'IsOcZ+Y-/I+O+Z-Y+
F'I+OcZ+Y-/IsO+Z-Y+
F'I-OcZ+Y-/I+O+Z-Y+
F'I+OcZ+Y-/I-O+Z-Y+

2.  Describe for yourself an imaginary prokaryotic operon whose characteristics can be explored using F' conjugation.    You may decide what mutants "have been found", whether the operon is inducible or repressible, the function of the gene products, etc., to tell a story.  Write a series of conjugations from which can be inferred that there is  (a) a cis-acting operator and  (b) a trans-acting regulator gene (inducer or repressor).  Be sure that you include the control experiments that demonstrate the nature of the mutants as well as wild type.  The data should be presented in the form of a table for easy interpretation.  Indicate what information is inferred from each conjugate, that is, why you included it for your demonstration.  These can be brief (mostly), for example: "control - demonstrates w/t phenotype",  "control - demonstrates constitutive operator phenotype", or  "control - demonstrates mutant structural gene phenotype", etc.  Hint - you may model your system on any of the ones we have studied - but yours must be imaginary!

Construct a table like the one in question 1.  Hand in one copy of this table with the answers included, and bring one copy of the table - BLANK - to class, to exchange with another student.  Also, post a copy on BlackBoard discussion group.