Question

The hunchback gene contains a promoter region, the structural region (the amino acid coding sequence), and a 3' untranslated region (DNA that will be transcribed into sequences appearing at the 3' end of the mRNA that are not translated into amino acids).

a. What important sequences required to control hunchback gene expression are found in the promoter region of hunchback?

b. What sequence elements that encode specific protein domains are found in the structural region of hunchback?

c. There is another important kind of sequence that turns out to be located in the part of the gene transcribed as the 3'UTR (untranslated region) of the hunchback mRNA. What might this sequence do?

Answer 1

a. Promoter region is a sequence require to turn the gene on and off and itself recorginize by RNA polymerase for further transcription. This region contain the binding site for RNA polymease as well as transcription factor that are required for its expression. Bicoid, an important transcription factor that aid the expression of hunchback. Thus, Bicoid acting as the transcriptional activator of Hunchback gene transcription. Binding sites for other transcriptional factor must be there in promoter region to factilictate the transcription of hunchback gene in proper and and for its uniform distribution in egg.

b. The gene code for specific hb, transcript variant A; hb transcript variant B. The structural gene of hunchback has specifc sequence element of activation domain and DNA binding domain to code for hunchback protein that marked the anterior end of drosophila along with Bicoid.

c. 3' UTR consist of certain specific sequence that play crucial role in expression og gene in terms of its localization, stability and transport. For example Pumilio binds to the 3' UTR region of the hunchback mRNA with nanos providing positional specificity restrict the hunchback to anterior end only.