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MERLOT II


    

Learning Exercise


Material: The Virtual Genetics Lab
Submitted by: Anita Klein on May 01, 2009
Date Last Modified: May 01, 2009
Title: Exercise for Virtual Genetics Lab II
Description: Orientation to VGL II and exercises in deducing modes of inheritance from simulated crosses.
Type of Task: Individual, Student-centered
Time Required 60 minutes
Topics: deducing modes of inheritance
Course: Principles of Genetics
Audience: College General Ed, College Lower Division
Categories:
Prerequisites Skills: Understanding of Meiosis Understanding of Mendel's laws
Learning Objectives: To take students beyond predicting the outcomes of crosses where the genotypes and modes of inheritance are specified, to deducing modes of inheritance of Mendelian traits from crosses.
Technical Notes: This is a simple exercise that follows the format of Brian White's practice problem.
Text of Learning Exercise: Virtual Genetics Lab Virtual Genetics Lab was created at U. Massachusetts Boston. The Virtual Genetics Lab is a simulation of transmission genetics that approximates, as closely as possible, the hypothesis-testing environment of genetics research. In this lab, students cross hypothetical creatures and examine the progeny in order to determine the mechanism of inheritance of a particular trait. As in actual research, it is not possible to 'see the answer' - the student must decide for herself when she has collected enough data to be sure of her model. The goal is to have students understand the logic of genetic analysis - how one can use crosses to determine how a trait is inherited and reinforce their understanding of transmission genetics. In order that the exercise is based on the logic of genetic analysis rather than student's ability to search the internet, the creature under study will be hypothetical, the traits will be assigned randomly, and the mode of inheritance will differ with each run of the program. Traits can be either autosomal or sex-linked (with XX females and XY males or with ZZ males and ZW females) and simply dominant or co/incompletely dominant. The form of the trait which is dominant, recessive or seen in the heterozygote will also be determined randomly. VGLII presents students with problems involving one to three genes and linkage. In this lab you will have to decide: • Which organisms to cross. • What are the possible modes of inheritance • How to interpret your data. • When you have enough data to be sure of your conclusions Running VGLII - Virtual Genetics Lab • To run VGLII simply double-click on the VGLIIx.x file. Note: Be sure to have the Problems folder in the same folder as the VGLIIx.x file. The toolbar buttons are shown below: • How To Start A New Problem • When you start VGLII, you will see a toolbar like this: From the "File" menu, select "New Problem" or simply click on the "New Problem" button on the toolbar and you will see a list of problem type files. The files are listed in increasing order of difficulty. Additional problem type files can be generated using the VGLAdmin program. Select the file and click on the "Open" button. • Once you start a problem, a window (Cage 1) will be opened up on the screen. This cage is the starting point for your project. The organisms can be, but are not necessarily, pure-breeding. Exercises: (For each problem fill in the attached summary sheet; if you complete all problems correctly, you win a prize.) 1. Problem 1: become familiar with VGLII a. Open problem level 01 in the practice mode: Level 01p.pr2 b. Resist the urge open the “Show the Genetic Model”! c. Cross a fly with phenotype A and phenotype B. i. What are the progeny phenotypes? ii. What is the ratio of the two phenotypes? iii. What is the sex ratio of each phenotype? iv. Repeat 1 ( c) several more times: d. Cross two flies with phenotype A: i. What are the progeny phenotypes? ii. What is the ratio of the two phenotypes? iii. What is the sex ratio of each phenotype? iv. Repeat 1 ( d) several more times: v. Are the flies with phenotype A true breeding? e. Cross two flies with phenotype B i. What are the progeny phenotypes? ii. What is the ratio of the two phenotypes? iii. What is the sex ratio of each phenotype? iv. Repeat 1 ( e) several more times v. Are the flies with phenotype B true breeding? f. Propose a genetic model for inheritance of this trait. Check it against the Genetic model for this problem 2. Level02.pr2 This time do not use the practice problem mode. What is the mode of inheritance of this trait? 3. Level 03.pr 2 What is the mode of inheritance of this trait? 4. Level 09.pr2 For this problem you probably want do more crosses and multiple generations. What is the mode of inheritance for each trait? What else can you deduce about the relationship between the two genes controlling these traits? 5. Level10.pr2 For this problem you probably want do more crosses and multiple generations. What is the mode of inheritance for each trait? What else can you deduce about the relationship between the two genes controlling these traits? 6. Level12.pr2 For this problem you probably want do more crosses and multiple generations. What is the mode of inheritance for each trait? What else can you deduce about the relationship between the genes controlling these traits? 7. Level13.pr2 For this problem you probably want do more crosses and multiple generations. What is the mode of inheritance for each trait? What else can you deduce about the relationship between the genes controlling these traits?
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