Following statement regarding to the cascade of regulated RNA splicing controls drosophila sexual differentiation.

A. The Sex-lethal (Sxl) protein, encoded by the sex-lethal gene, is the first protein to act in the cascade and present only in female embryos.

B. Early in development, the Sxl gene is transcribed from a promoter that functions only in male embryos.

C. Later in development, this male-specific promoter is shut off, and another promoter for sex-lethal becomes active in both male and female embryos.

D. In male embryos, however, in the absence of early Sxl protein, exon 3 of the sex-lethal pre-mRNA is spliced to exon 2 to produce an mRNA that contains a stop codon early in the sequence.

Which of the following is correct?

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#Question id: 28913

#Unit 4. Cell Communication and Cell Signaling

Frizzled-G protein signaling activates__

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#Question id: 3672

#Unit 3. Fundamental Processes

During initiation of replication

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#Question id: 12127

#Unit 10. Ecological Principles

Species richness increases

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#Question id: 5004

#Unit 11. Evolution and Behavior

Pax-6 usually causes the production of a type of light-receptor pigments. In vertebrate eyes, though, a different gene (the rh gene family) is responsible for the light-receptor pigments of the retina. The rh gene, like Pax-6, is ancient. In the marine ragworm, for example, the rh gene causes production of c-opsin, which helps regulate the wormʹs biological clock. Which of these most likely accounts for vertebrate vision?

TLS Online TPP Program

#Question id: 4070

#Unit 3. Fundamental Processes

An enhancer

a. can be located upstream of a promoter.

b. can be located downstream of a promoter.

c. can be located a variable distance from the promoter.

d. is always located within 1 kb of the promoter.

e. can be cell-type-specific.