Talk: Genetic code
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Someone should write about all exception from basic scheme. Taw
The article was kind of hard to read, so I'm doing some significant modifications. Let me know if these are ok. I'd really like to take the start codons out of the table, since they have considerably more variability than the rest of the code (differ between eukaryotes and prokaryotes), and aren't really sufficient for a start anyways. Also, why do we always capitalize STOP and START?
So DNA is not in "genetic code?" Also, DNA and genes are not organized into codons? This needs clarification; also, ought not the article to define intron and exon? Slrubenstein
- Not sure what you mean by DNA not being in "genetic code", DNA is mentioned in the second paragraph and is the medium in which genetic encodings are written. Also, yes, DNA and genes are organized into codons; a codon is simply a group of three nucleotides, like the way a byte is a group of 8 ones and zeroes. As for introns and exons, they might be worth a mention but I don't think they're really directly relevant to an article about the genetic code. introns and exons are dealt with in "preprocessing", before RNA gets to the protein-translating machinery. Bryan
The first sentence reads:
- The genetic code is the code used to translate a sequence of RNA nucleotides into protein.
Now, I assume that this is how biologists talk -- trust me, a non-biologist would eagerly look to the next sentence to find out what "translate" means in this context (or might just give up; remember, this is not a textbook, readers do not have professors or TA's to explain things, it has to be all here). So, not being sure what the technical meaning of translation is here, all I see is that there is no mention of DNA in the first sentence, only mention of RNA. Even knowing a fair amount of biology, this sentence leads me to think that the code is used in the RNA itself. There is nothing in the first sentence to suggest that the RNA is forming complementary bases from a strand of DNA which uses the same code. Look, I am not trying to be argumentative. I think the first sentence needs to be clear to leaypeople, and provide a good general definition. I really think a layperson would be pretty confused. Also, concerning codons, according to the first part of the article, codons are parts of RNA -- the implication is that they are not parts of DNA. Don't you see what I mean? The article may provide an accurate description of the process of transcription, which may be the main function of "genetic code," but it is not introducing the lay-person to what words like "genetic code" and "codon" mean in a clear way. Slrubenstein
- Translation starts with a chain initiation or START codon, but unlike STOP codons these are not sufficient by themselves to begin the process; nearby initiation sequences are also required to induce transcription into mRNA and binding by ribosomes
What are "nearby initiation sequences"? Are we talking about cell processes that get DNA transcription/translating going, or are we talking about special sequences of codons? If the latter, why isn't it more accurate to drop talk about "start codons" and speak only of "start sequences" of codons? --Ryguasu 01:45 Jan 31, 2003 (UTC)
What's with all these alternate starts? I can find one reference on pubmed that talks about GUG starts, in mtDNA. Nothing for CUG. Why are they given simply as 'start', with no annotation or caveats? For all practical purposes there's really only one start codon, the rest are basically just novelties, and the text ought to emphasize this. Unless someone has a reference saying otherwise? Graft 16:14, 9 Apr 2004 (UTC)
- Wup. Never mind, found lots about alternate initiation. But I still think the text should emphasize that AUG is the norm. Graft 16:15, 9 Apr 2004 (UTC)
I edited the bit about redundancy a bit and removed the insinuation that met only has one codon because it is the start site; since the start site is recognized by a separate tRNA than the met-tRNA for normal elongation, it is not necessary that these two properties be coupled. That is, met could have redundant codons, and only one of them need specify the start site. Graft 18:30, 13 Jul 2004 (UTC)
What are start and stop codons?
There is no explanation in the text. ··gracefool |☺ 01:56, 27 Sep 2004 (UTC)
- The defintion is in the article, but rather implicit: Translation starts with a chain initiation codon (start codon). But unlike stop codons, these are not sufficient to begin the process; nearby initiation sequences are also required to induce transcription into mRNA and binding by ribosomes. The most notable start codon is AUG, which also codes for methionine. CUG and UUG, and in prokaryotes GUG and AUU, also work.
- Pjacobi 11:08, 27 Sep 2004 (UTC)
