2. The results of your complementation test suggest that your blue frog likely h

Question

2. The results of your complementation test suggest that your blue frog likely has a mutation in pigment production. Five genes responsible for yellow pigment production were discovered in a previous zebrafish screen. The DNA sequence for both these genes can be located in the gene database hosted at the NCBI website (national center for biotechnology information).

A. Describe how you can use a southern blot to determine if the genes for yellow pigment production identified in zebrafish are conserved in the frog genome.

B. You discover three of the zebrafish genes for yellow pigment synthesis are conserved in the frog. You decide to run a northern blot and a western blot to determine to see which of these are expressed in your blue frog. You decide to test samples from your blue frog and a true breeding green tree frog.

a. What does a northern blot measure? What result to you expect from a northern blot for a gene expressed in your blue tree frog?

b. What does a western blot measure? What results do you expect from a gene that is expressed in your blue tree frog?

c. How does including the green frog in the experiment help you interpret your results?

d. Your assistant decides to harvest blood from the tree frog for this experiment to obtain a lot of cells with minimum harm to the frog. Explain to the assistant why this sampling strategy will not tell you whether the gene for yellow pigmentation are expressed in the frog.

Explanation / Answer

A. You identify the genes in the southern blot (checks for DNA) by comparing the DNA in the zebrafish to the DNA in the frog. If they match up where the genes have been identified, then the genes are conserved in the frog. B. a. Northern blot measures RNA, I expect that if the three genes conserved to produce yellow pigment in the zebra fish are the three genes in the frog required to produce the yellow color, that one or more of the genes may not transcribe. It also remains a possible that they all transcribe, but not all translate. b. Western blot measures proteins, I would expect one or more the essential proteins that make up the yellow pigments to not be expressed. c. The green frog in theory would have three fully expressed proteins from the three essential genes coding for yellow pigment and the blue frog would be lacking either one or more of these at the transcription or translation level in terms of inhibited RNA or inhibited protein synthesis. d. The epidermal layers is where the yellow pigment is expressed. The blood is the blood.

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