mRNA

Prokaryotic Gene Regulation

subject to regulation - an mRNA copy is made from the DNA and

mRNAs which have AUG (start) and stop codons and are translated into

Southerns, Northerns, Westerns, & Cloning: Molecular Searching Techniques

thousands of genes, thousands of different mRNA species, and thousands

plasmid, a pure mRNA transcript, or a purified protein. In this case,

Solving Problems

you tell this?), explain the difference between the mRNA for this gene

i) First, what do the blots show? Since the target molecule is mRNA,

detect the presence of a different exon or exons in the final mRNA.

From this, we can determine which exons are present in the mature mRNA's.

Blot A shows that exon 1 is present in both male and female mRNA

Blot B shows that exon 1 and/or exon 2 are present in both mRNA

Blot C shows that exon 2 is present in the female mRNA but not

in the male mRNA - note that this does not conflict with Blot B's

Blot D shows that exon 3 is present in both male and female mRNA

Summarizing: female mRNA for this gene contains exon 1, 2, and 3 - this

is expected pattern of splicing; male mRNA for this gene contains only

sizes of the mRNA's in both sexes. We would predict that in females,

mature mRNA = 0.5 + 0.2 + 0.6 = 1.3knt; and in males, mature mRNA = 0.5

Note that the size of the mRNA observed in each sex does not change even

You would predict that the mature mRNA for this gene would be 0.5 + 0.2

apparently normal splicing of the pre- mRNA. Therefore, in females, the

In males, the mature mRNA is 0.2knt shorter. There are three

exons would be present in the mature mRNA. This is not observed - blot C

that exon 2 is missing in the mature mRNA from this gene in males.

exon 2, and only exon 2 is somehow missing from the mature mRNA in

another 90nt along the mRNA. (the average amino acid is 0.1kDa)

- Lane 2: No gene W mRNA will be produced, so no protein W will be

mRNA made by the F' of 40KDa; and mutant, from mRNA made from the