Introduction:

The laboratory project is an opportunity to study the basic mechanisms of transmission genetics in Eukaryotes using the fruit fly, Drosophila melanogaster.  A description of this organism and its life cycle can be found in your laboratory manual (Carolina Drosophila Manual).  The object of the project is to determine the mode of inheritance of a single mutant characteristic.  To do so you will learn to maintain and manipulate the fruit flies, to make genetic crosses, and to collect, analyze and interpret data.

Organization:

The class will be divided into groups of two.  The two members of a group will study the same mutant characteristic.  One member of each group will undertake a set of crosses designated the "A" set (see below).  The other member will do the "B" set.  Data from the "A" and "B" sets will be used to determine the mode of inheritance of the mutant characteristic.

Subcultures:

You and the other member of your group will each receive two cultures of fruit flies.  One culture breeds true for the normal form of each characteristic.  This culture is the "wild type" stock.  The other culture breeds true for a mutant form of one characteristic and is called the "mutant" stock.  You must maintain these pure breeding stocks throughout the semester by making 3 to 4 subcultures of each every week.  Click here for the procedure for making subcultures.

Crosses:

Set A Crosses:

1. Make the following Parental (P) Cross:

Wild Type Virgin Female  X  Mutant Male  >>>>  F₁(a) Offspring

2. Make the following F₁ X  F₁ Cross:

F₁(a) Female  X  F₁(a) Male  >>>>  F₂(a) Offspring

Set B Crosses:

1. Make the following Parental (P) Cross:

Mutant Virgin Female  X  Wild Type Male  >>>>  F₁(b) Offspring

2. Make the following F₁  X  F₁ Cross:

F₁(b) Female  X  F₁(b) Male  >>>>  F₂(b) Offspring

One member of each group will do Set "A" and the other Set "B".  Click here for details on making a Parental (P) Cross.   For details on making an F₁  X  F₁ Cross, click here.  Plan to set up several (5 or 6) vials of each type of cross with the hope of collecting data on a few (3 or 4).  Be sure to record the sex and phenotype of all offspring from both Parental and F₁  X  F₁ Crosses that emerge during the first ten days of hatching.

Data Analysis:

You will be provided with a Project Report Form that will assist you in organizing and analyzing the data.  When appropriate the data will be tested using a Chi Square Analysis to determine if the observed results fit the expected ratio.  An explanation of the Chi Square Analysis will be presented in class and is also available in your lecture text (Klug and Cummings).

Conclusions:

Based on the analysis of your data you are to determine if your mutant gene is:

• an Autosomal Dominant

• an Autosomal Partial Dominant

• an Autosomal Recessive

• an X - Linked Dominant

• an X - Linked Partial Dominant

• an X - Linked Recessive
   

CONTACT PERSON:  Robert Weibust - weibust@mnstate.edu

LAST UPDATE:  5/17/04

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