2. Both the ftz gene and the engrailed gene encode transcription factors that ar
ID: 215596 • Letter: 2
Question
2. Both the ftz gene and the engrailed gene encode transcription factors that are capable of activating the expression of other genes. The ftz and engrailed genes are expressed at about the same time and place during Drosophila development. Investigators wanted to know whether one of these genes might regulate the expression of the other. (a) Write out the four possible arrangements for regulation of Ftz and Engrailed by one another, using the and symbols. (2 pts) To distinguish between these arrangements, the researchers performed two experiments. They generated mutants that lacked any Etz protein and then observed the level of Engrailed protein None was present In a separate experiment, they generated mutants that lacked any Engrailed protein. When they examined the expression of Etz protein, they found that Etz was present at the correct time & place. - (b) Which of the four arrangements from part (a) best matches the observed data? Describe how the observed data eliminate or provide evidence for each of the four regulatory arrangements (3 points).Explanation / Answer
A) the four possible arrangements are
- Ftz -> Engrailed protein Ftz initiates engrailed protein production
- Ftz -| Engrailed protein Ftz represses engrailed protein production
- Engrailed protein -> Ftz Engrailed protein initiates Ftz production
- Engrailed protein -| Ftz Engrailed protein represses Ftz production
B)Given
- when engrailed protein was knocked out, Ftz was found at correct time and place.
- when Fts was knocked out, engrailed protein was absent
By this we can infer,
- Engrailed protein has no effect on the expression of Ftz protein. As no chnage in its behavior was observed when engrailed protein was knocked out.
- Ftz protein is required for the production of engrailed protein, as engrailed protein was lost in a Ftz knockout strain.
THerefore Ftz is required for the production of engrailed protein and does so by activating its production.
Hence the correct option is Ftz -> Engrailed protein Ftz initiates engrailed protein production
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