General Question

Zyx's avatar

Are both sides of the DNA helix used for the same amino acid?

Asked by Zyx (4011 points ) October 24th, 2010

I’ve seen hundreds of representations in which the sides of the DNA helix mirror eachother. Now I’m wondering whether these sides function together or seperately or perhaps just one of them is copied into RNA. What is the deal?

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5 Answers

shilolo's avatar

Typically only one strand is used as the template for messenger RNA synthesis, but some regions of DNA can encode multiple RNAs that are transcribed from opposite strands.

Zyx's avatar

I actually asked because I was thinking how amazing “opposite strands” would be. But a single occurance in rats hearts doesn’t really prove viability. As long as we don’t know what the second side does it might as well be dead weight.

EDIT: added quotation marks in order not to seem too arrogant. Does that make me seem desperate for approval? Does THAT make me seem desperate for approval? How about this? When did this become annoying?

gasman's avatar

I’m confused on this point myself, but @shilolo‘s first link explains…:

Although DNA is arranged as two antiparallel strands in a double helix, only one of the two DNA strands, called the template strand, is used for transcription. This is because RNA is only single-stranded, as opposed to double-stranded DNA. The other DNA strand is called the coding strand, because its sequence is the same as the newly created RNA transcript…

…though it’s still not clear to me which of the two strands normally gets chosen as the template.

shilolo's avatar

@Zyx It isn’t a single occurrence (that paper was from 1987). There are many other examples as well, best exemplified by the cis acting long non-coding RNAs.

As for which strand is “chosen”, it isn’t really a “choice” so much as the evolution of specific transcription start sites and promoters that dictate where RNA polymerase will bind and initiate transcription.

gasman's avatar

@shilolo Right, makes sense. I think maybe I used to know that…

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