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Virtual Biology Laboratory Student: __________________________ Date: __________________________ Module: Genetics Exercise I: Phenotypes No worksheet is needed for this exercise. Exercise II: Chromatography Part A: Using Thin Layer Chromatography to Separate the Components of a Mixture Be sure to calibrate the Rf ruler as per the instructions in the Options section. Drag and drop the extracts from the uppermost family of glyptodonts (the white box next to the picture) into the blue box at the base of the chromatography apparatus. Press Start. When the solvent front has traveled an appropriate distance, click Stop. Then having calibrated the Rf ruler, note the number of pigments detected in the two extracts, their color, and their Rf value. The Rf value can be determined by dragging the purple ruler down until the purple line is aligned with the middle of the molecule of interest. Repeat for the other three pairs of glyptodonts. Genotypes of Parents Number of Pigments Color(s) Rf value(s)approximate Aa X Aa Aa X aa AA X aa aa X aa 1. How many pigments were detected in each sample? ____________ 2. Are the pigments the same in each sample? ______ Yes _______ No 3. What is the color and Rf of each pigment molecule detected? Copyright ©2003 Wadsworth, a division of Thomson Learning, Inc. Thomson Learning is a trademark used herein under license. VBL/Genetics Page 2 ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ 4. How do the colors and Rf values of the pigments correlate to the shell colors of the glyptodonts? ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ Exercise III: Electrophoresis Load the Standard Molecular Weight Marker (ST ) by dragging it from the sample panel to the right of gel apparatus and placing it into one of the four wells at the top of the gel. Load one or more protein samples extracted from organisms with known genotypes by dragging the appropriate box (AA, Aa, aa) from the panel to the right and placing it into one of the remaining wells. Click the Start button on the PowerPac power supply. When the visible marker on the right hand side of the gel holder gets near the bottom of the gel, click the Stop button. Now click Stain. When staining is complete, all proteins will stained various shades of blue. By comparing proteins detected in your extracts with proteins of know molecular mass in your standard, the size of approximate size of the unknown proteins can be determined. Make special note of the approximate weight of any proteins that appear to be found in one sample but not another. You may sketch the results of your electrophoresis experiment using the diagram below. Copyright ©2003 Wadsworth, a division of Thomson Learning, Inc. Thomson Learning is a trademark used herein under license. VBL/Genetics Page 3 Copyright ©2003 Wadsworth, a division of Thomson Learning, Inc. Thomson Learning is a trademark used herein under license. VBL/Genetics Page 4 Is the presence or absence of a particular protein(s) correlated with the presence of absence of a particular allele(s)? ______ Yes _______ No Since genes are expressed by coding for the production of individual proteins, do any proteins found appear to be under the control of any particular allele(s)? ______ Yes _______ No Copyright ©2003 Wadsworth, a division of Thomson Learning, Inc. Thomson Learning is a trademark used herein under license. VBL/Genetics Page 5 What can you conclude about the relationship of specific proteins to the presence or absence of specific alleles? ________________________________________________________________ ________________________________________________________________ ________________________________________________________________ Exercise IV: Genotypes Start a problem by clicking the New button. You will be presented with phenotypes for the parents (P1a and P1b) and offspring (F1) for the first mating between the parents. If you think you know the genotypes of the parents, select the appropriate genotypes for both parents from the choices on the pull-down menus located in the boxes to the right of P1a= and P1b=. If you cannot make a reasonable choice, you will have to perform a second mating. To initiate the F2 mating, select and drag any two individuals from the P1a, P1b, or F1 (parents or offspring) into P2a and P2b. When both P2 parents are in place, you will be presented with the phenotypes for the F2 offspring. Additional F2 matings may be performed by clicking the Reset F2 button. Based on the results of your mating experiments, you should be able to answer the following questions and explain why your answer is correct. 1. AA X AA: Are both parents "true breeding" for shell color? That is, will the dominant phenotype be found in all of the offspring? ______ Yes _______ No 2. Aa X Aa: In the offspring from this cross, 75% are red and 25% are yellow. Is this what you would predict? ______ Yes _______ No 3. AA X Aa: The probability of getting a yellow shelled glyptodont from this mating is 0%. ______ True _______ False Copyright ©2003 Wadsworth, a division of Thomson Learning, Inc. Thomson Learning is a trademark used herein under license. VBL/Genetics Page 6 4. aa X aa: This is the only cross that ensures all yellow shelled offspring. ______ True _______ False 5. A? X aa: This type of cross is the ONLY way to determine the genotype of the first parent. ______ True _______ False 6. Does shell color appear to be under the control of a single gene with two alleles, where the dominant phenotype is red and the recessive is yellow? ______ Yes _______ No 7. After the results of your chromatography and electrophoresis experiments, can you reasonably conclude that the red shell color is produced by a single red pigment whose synthesis is catalyzed by an enzyme (approximate mass of 45 kd) coded for by the dominate allele? ______ Yes _______ No Copyright ©2003 Wadsworth, a division of Thomson Learning, Inc. Thomson Learning is a trademark used herein under license.