Ex_8_Computer2009

Ex_8_Computer2009 - 101 EXERCISE 8 PLANT GENETICS V...

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Unformatted text preview: 101 EXERCISE 8 PLANT GENETICS V COMPUTER GENETICS ( DROSOPHILA ) SEX LINKAGE AND HUMAN GENETICS Equipment and supplies needed: Computers F2 Seedlings Forceps Paper Towels PART I: Observation and Analysis of Brassica Seedlings The purpose of this exercise is to harvest and germinate the F2 fast plant seeds and to investigate two variations of the dihybrid cross using a computer simulation. Examine the F2 Brassica seedlings which have germinated on the moist filter paper. Classify each seedling according to hypocotyls length In the space below, write down the all the possible phenotypes and the number of seedlings you observed with those phenotypes: Phenotypes Number Observed 1. What is the ratio of the phenotypes (observed)?___________ 2. Recall that the original parental strains were RRYY and rryy . These were crossed to yield the F1 seeds which you planted in Exercise 1. The wild-type parent produced only RY gametes and the mutant parent produced only ry gametes. The only possible genotype for the F1 hybrids, therefore, was RrYy (Diagrammed in Exercise 2) Exercise 8: Computer genetics 102 3. Complete the following Punnett square to show the expected genotypes of the F2 seedlings. male gamete female gamete 4. What is the expected ratio of each phenotype?___________ 5. Do the observed and expected ratios differ?________________ 6. How would you decide if this difference was significant or not? _______________ PART II: Computer Genetics of Drosophila "Die Aufgabe is nicht nur zu sehen was noch keiner gesehen hat, sondern bei dem was jeder sieht, zu denken was noch keiner gedacht hat. " Schopenhauer We do not have to see what no one has seen before, but rather, to see what everyone has seen and then to think what no one has thought before. The science of genetics began with the observations of the patient monk Mendel, who saw what everyone had seen, but thought what no one else had thought before. Within 150 years, progress in this field has brought us to the point where we can understand and alter ourselves by changing the sequences of our genes. The Dihybrid cross - linked 1. Double click on 1. The Dihybrid Cross Exercise 8: Computer genetics 103 2. Click once on Couple #1 . Two flies will be placed on the screen. Both have red eyes (allele A) and clear wings (allele B). 3. Click on Couple #2 . two more flies will appear. These have white eyes (allele a) and spotted wings (allele b). A closer examination of these flies will reveal their genotype. The following procedure is only possible in the world of computer genetics. 4. Click the microscope icon (=picture) and move the microscope with the mouse to one of the flies. Then click again and the genotype and arrangement of the alleles on the chromosome will appear. Leave the microscope image over the fly while you examine the chromosomes....
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Ex_8_Computer2009 - 101 EXERCISE 8 PLANT GENETICS V...

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