Question

A map is shown below for a gene that uses alternative splicing. 5 splice sites are indicated with a 5, while 3 splice sites are indicated with a 3. Boxes below the gene are used to represent the presence of sequence elements found in the pre-mRNA for this gene. Splicing enhancers are shown as filled boxes, while splicing silencers are shown as stippled boxes. The enhancers and silencers only act on the splice site that they overlap (eg., the stippled box affects the 3 splice site at B/C). In the absence of activators and/or repressors, you can assume that the 5 and 3 splice sites closest to each other will always be used. Each potential gene segment is given a letter. Use the letter code to answer the following questions. For example, if the only splicing that occurred was between the AB 5 and B/C 3 splice site, the product would be written as: ACDEFGH. What does the mRNA from this gene look like in the absence of splicing activators and repressors? What does the mRNA from this gene look like in the presence of only splicing activators? What does the mRNA from this gene look like in the presence of only splicing repressors? If you could ADD or REMOVE any splicing enhancers or silencers in the pre-mRNA, describe how you could get the pre- mRNA to splice to make an AH mRNA (you may assume that any required activators or repressors are present).

Answer 1

In molecular biology splicing is the editing of the nascent precursor mRNAtranscript.after splicing,Introns are removed and Exons are joined together.Some transcription factors activate transcription i.e they may help the general transcription factors and RNA POLYMERASE bind to the promoter whereas a represser may get in the way of the basal transcription factors or RNA polymerase,making it so they can not bind to the promoter or begin transcription