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Old 05-27-2011
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DNA Stop codon HELP!

I'm a little bit confused here:

In Tay-Sachs disease, the frameshift mutation a 4 base insertion lead to formation of a stop codon TGA (RRPathology pp 82)
tay sachs.bmp

So, the DNA would be
5' - TGA - 3'

Then the RNA pol. will read this from the 3'to5' and the new RNAm will be:

3' - AGT -5' => 5' - UCA - 3'...and then the ribosome read this from 3'to5' or from 5'to3'? (I'm trying to get the stop codon UGA...)
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Old 05-27-2011
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Hey singapur_md, I think you just made a simple mistake.

The complimentary strand of TGA is ACT, not AGT

If you use ACT, then you will come up with UGA.

But instead of going through that whole process, we can use the concept of template vs coding strand to our advantage. If a gene sequence is given 5' ---> 3' (we always assume it is unless otherwise stated), all we have to do to get the mRNA sequence is replace the T's with U's

Thus 5' TGA 3' on DNA = 5' UGA 3' on mRNA
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singapur_md (05-27-2011), zen228 (04-16-2014)


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