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ETD 44: A. What are the secret tricks to solving modes of inheritance in drosophila? B. Why is this tiger swallowtail 1/2 yellow and 1/2 black?
January 24, 2014 at 8:07am

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Chloe Hobson
January 25, 2015 at 6:20pm

Student: The secret to solving modes of inheritance problems with drosophila are-

1. solve one first AaTt

2. Isolate a pure bred-homozygous recessive-aa (Mendel)

3. Test cross- ??xaa. This shows dominant vs. recessive. Hetero: 1:1 Homo: 4:0

4. Autosomal vs. sex-linked (if it is not 1:1--sex linked)

5. Linkage or not..linkage--on same chromosome. Look at ratios. 

The butterfly is half yellow and half black because it is a gynandromorph and is therefore half male and half female. There is codominance, so both traits appear. I explained that problems in meiosis result in genetic disorders. I also explained that the butterfly shows codominance, which is also seen when red and white flowers result in progeny with some white and some red flowers. Both traits appear. 

Parent: I found the information on the butterfly very interesting because I had never heard of the term gynandromorph and learned a new concept. I also now understand how my student solves genetics problems and enjoy seeing her grasp the concept and her excitement to teach me how to solve these problems. 

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