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To: ahayes

Nope, strand 2 is non-coding.


993 posted on 09/16/2006 5:29:36 PM PDT by GourmetDan
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To: GourmetDan

Where do you get that, dear?


1,009 posted on 09/17/2006 4:14:34 AM PDT by ahayes (My strength is as the strength of ten because my heart is pure.)
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To: GourmetDan
If you think only one strand contains genes, please go here and examine the sequence of the human chromosome. You can see that some genes are oriented in one way and some in the other. Examination of the tooltip there says, "Orientation--Down arrow: Positive strand, Up arrow: Negative strand."

You might also examine this viral DNA. You can see one open reading frame runs the opposite direction from the other two. That's because it's on the other strand. Some viruses have to pack the information in so tightly that they've managed to overlap open reading frames, so one segment of DNA will produce one product and its complement on the other strand will produce a different product. The presence of genes on both strands is easily demonstrated by examining a variety of different plasmids.

Now we can also go back and zoom in on a gene in the Y chromosome. You can see here that the selected gene, SRY (the sex-determining master switch, errors in this gene can result in a female with and XY genotype), runs in the opposite direction from the surrounding genes (SRY is on the minus strand, the others on the plus strand). Of course you know that this means they can't be on the same strand, since strands are transcribed 5'->3'.

I wonder how you got the idea that only one strand has information on it, and why you think this is required. If we mentally examine the two DNA strands of a duplex, both strands are pretty much the same so far as a ribosome is concerned--they both have the four bases and they both run 5'->3'. An open reading frame on either strand will be transcribed.

1,011 posted on 09/17/2006 5:00:29 AM PDT by ahayes (My strength is as the strength of ten because my heart is pure.)
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