Question

An experiment was conducted in which sections of a eukaryote’s DNA were deleted to see the impact on mRNA production. In each case, transcription was measured by looking at the number of transcripts produced after the gene expression was induced. Given the data below, explain why each of the deletions has the impact it does (or does not). For reference, a wild-type cell (no deletions) produced 15,000 transcripts in this experiment.

Region deleted (all regions are upstream of the transcription start site	Amount of mRNAproduced (# of transcripts produced in 10 minutes after gene induction)
-1500 through -1200	1000
-1200 through -900	15000
-500 through -350	15000
-350 to -100	1000
-100 to -1	0

Answer 1

From -1500 to -1200 enhancer is present, therefore less mRNA is produced. Similarly, in -350 to -100 also, enhancer sequencer is present.

In -1200 to -900 and -500 to -350 there is only junk DNA, which has no impact on mRNA sequence. Therefore there is no effect in the number of mRNAs produced.

In -100 to -1, promoter is present. When this is deleted, RNA polymerase is unable to bind, and mRNA synthesis does not occur.