Geneticists have identified a number of mutations of the Drosophila gene, Dorsal. Most mutant alleles result...

Geneticists have identified a number of mutations of the Drosophila gene, Dorsal. Most mutant alleles result in dorsalized embryos, i.e. all tissues are dorsal. But one mutant allele is dominant to wild-type and results in ventralized embryos, i.e. all tissues are ventral. How can these results can be explained? Choose from answers below.

1. Mutant Dorsal cannot bind Spätzle.
2. Mutant Dorsal cannot bind Cactus.
3. The Dorsal gene is constitutively expressed in the mutant.
4. Mutant Dorsal cannot bind DNA.
Mutant Dorsal initiates signal transduction in the presence or absence of Toll.

Expert Solution

Option B, mutant dorsal can not bind to cactus.

In ventral part of drosophilla , pipe protein synthesis occur which cause formation of ventral side. This pipe protein synthesis is stimulated by protein dorsal , which bind to specific part of DNA and stimulate synthesis of pipe protein .

Normal condition, In absence of any activation signal from toll receptor Dorsal protein remain in cytosol in binding with cactus. Once toll protein get activated, it cause phosphorylation of cactus and its degradation. Thus cause release of dorsal and its entry in to the nucleus and ventral axis formation. This is tightly regulated process .

Only presence of signal,phosphorylation of cactus and its degradation, cause release of dorsal-- lead to ventralization

But if there is any mutation in dorsal protein that it can not bind to cactus than it always enter in to nucleus and promte ventral side formation. Option B is correct

gladiator answered 1 year ago

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