# Would aliens have DNA? **URL:** \ **Category:** Factual Questions\ **Created:** [August 7, 2003, 7:23pm UTC](https://boards.straightdope.com/t/would-aliens-have-dna/193647 "2003-08-07T19:23:37Z")\ **Posts on this page:** 6\ **Page:** 2
**Author:** ![Apoptosis](https://avatars.discourse-cdn.com/v4/letter/a/ba9def/32.png) [@Apoptosis](https://boards.straightdope.com/u/Apoptosis)\ **Post date:** [August 8, 2003, 3:02am UTC](https://boards.straightdope.com/t/would-aliens-have-dna/193647/21 "2003-08-08T03:02:09Z")
Hey **jharmon** : > [@](#): > > …because it would mean that the code wasn’t random at all… Evidence already exists that the code is not random. > **[The code within the codons - PubMed](https://pubmed.ncbi.nlm.nih.gov/2650752/?dopt=Abstract)** > > For the first time it is shown that each of the three codon bases has a general correlation with a different, predictable amino acid property, depending on position within the codon. In addition to the previously recognized link between the mid-base... Just for interest’s sake. -Apoptosis ---
**Author:** ![Jon\_the\_Geek](https://avatars.discourse-cdn.com/v4/letter/j/bbce88/32.png) [@Jon\_the\_Geek](https://boards.straightdope.com/u/Jon_the_Geek)\ **Post date:** [August 8, 2003, 3:15am UTC](https://boards.straightdope.com/t/would-aliens-have-dna/193647/22 "2003-08-08T03:15:53Z")
> [@](#): > > \*Originally posted by Apoptosis \* > \*\*Hey **jharmon** : > > Evidence already exists that the code is not random. > [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list\_uids=2650752&dopt=Abstract](http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2650752&dopt=Abstract) > > Just for interest’s sake. > > -Apoptosis \*\* Thank you! That’s exactly what I was searching for, but I apparently didn’t put in the right keywords 🙂 However, that code-within-the-codons is probably still random. If the aliens had DNA, and they used triplet codons, chances are they’d have their own code-within the codons that was totally different than ours… probably… 🙂 ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [August 8, 2003, 3:18am UTC](https://boards.straightdope.com/t/would-aliens-have-dna/193647/23 "2003-08-08T03:18:37Z")
The term “nonsense codon” is sometimes used to mean a codon that results in the insertion of an “incorrect” amino acid in a protein. In other words, it signifies a mutation from the normal sequence. The term is also used to express the random sequence resulting from the addition of a base to an otherwise normal gene. When the gene is expressed, you get part of the protein sequence expressed normally, followed by a nonsense sequence which teminates at a frameshifted stop codon. > [@](#): > > This would really take a big statistical study to get to where I thought it was… Yes it would. However people have been doing studies like this since the 80’s. It turns out that the codon table used by most organisms is pretty good at minimizing mutational errors in comparison to a randomly selected table. This is not quite on target, but at least gives the flavor of the discussion: [On the Evolution of Primitive Genetic Codes](http://216.239.53.104/search?q=cache:3ApNS6sAYxQJ:www.santafe.edu/sfi/publications/Working-Papers/02-08-034.pdf+%22genetic+codes%22+evolution+%22codon+usage%22&hl=en&ie=UTF-8) > [@](#): > > The Universal Code appears to be optimal or at least near optimal in > some sense. For example, Freeland et al. [29] show that the Universal Code > is near optimal in terms of error minimization ---
**Author:** ![Apoptosis](https://avatars.discourse-cdn.com/v4/letter/a/ba9def/32.png) [@Apoptosis](https://boards.straightdope.com/u/Apoptosis)\ **Post date:** [August 8, 2003, 5:54am UTC](https://boards.straightdope.com/t/would-aliens-have-dna/193647/24 "2003-08-08T05:54:02Z")
Hey **jharmon** : It took me a number of tries to find the right keywords! I had the privilege to hear a talk given by Dr. Taylor on this very subject. Interesting stuff. Maybe it’s random, maybe it really means something. I have no idea what that something would be! Hey **Squink** : > [@](#): > > The term “nonsense codon” is sometimes used to mean a codon that results in the insertion of an “incorrect” amino acid in a protein. I think this would be an incorrect usage of the term. There are three nonsense codons: amber, ocher, and opal. All of these are terminators of translation. You may be thinking of **mis** sense mutations, where a codon is altered in such a way that it encodes a different amino acid. As for frameshifting, we are talking about point mutations- frameshifts are not going to come into play. -Apoptosis ---
**Author:** ![eburacum45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eburacum45/32/8690_2.png) [@eburacum45](https://boards.straightdope.com/u/eburacum45)\ **Post date:** [August 8, 2003, 7:04am UTC](https://boards.straightdope.com/t/would-aliens-have-dna/193647/25 "2003-08-08T07:04:32Z")
PNA, eh? Excellent… So even if an alien biota does use DNA, at some early stage in the development of life the primitive code for transcription will have evolved independently, and would be completely incompatible with the Earth Code. is this right? I imagine, without much evidence, that alien life would contain many novel proteins and other organic comounds not found in Earth life, and so would be rendered completely inedible. most extrasolar systems are likely to contain a slightly different mix of heavy metals and other elements to those found on Earth, considering that most sun-like stars in our region will have been formed long ago in widely separated parts of the Galaxy. This also suggests a certain incompatibility in biochemistry. Farming and predation of and by alien lifeforms seems very unlikely, for this reason; but I expect that microbes from both alien and Earth populations may well be able to break down either side into some sort of usable form, so a limited amount of cross-infection and even disease might be possible… * * * SF worldbuilding at [http://www.orionsarm.com/main.html](http://www.orionsarm.com/main.html) ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [August 8, 2003, 1:13pm UTC](https://boards.straightdope.com/t/would-aliens-have-dna/193647/26 "2003-08-08T13:13:42Z")
> [@](#): > > \*Originally posted by Apoptosis \* > Hey **Squink** : > I think this would be an incorrect usage of the term… > -Apoptosis Yes it’s a technically incorrect use of the term. I was trying to get at the broader context of how the term is used once it leaves the undergrad classroom. Linguistics, not science. Sorry I didn’t make that clear. [Previous page](https://boards.straightdope.com/t/would-aliens-have-dna/193647.md?page=1)