June 28, 2010 at 12:00 pm #13495
Hi everyone ,
We all know what the genetic code is and how it’s in a specific arrangement and combination in each of the living forms … my question is : "can other combinations of the genetic code (apart from the already existent combinations) produce forms that is suitable for living ?"
If the answer is "No" , please tell me why ?
If the answer is "Yes", please tell me more 😀
thanks in advance …..
June 28, 2010 at 7:21 pm #100342
If the question is "could other…": then yes,
If the question "are there any other…": then no
The reason: LUCA and historical contingency.
June 28, 2010 at 9:25 pm #100345
thanx canalon for your reply … but actually i’m not a biologist , i’m a physics student who is interested in these stuff so please illustrate…
another question , what about genetic mutations and mutants , can’t it be an answer to my question ?
i mean that a specific species has a specific combination of genetic code and when a mutation happens this combination changes into another combination (due to changes in single nucleobases or whole codons).
This new combination of the genetic code could produce a new individual of the same species that has new properties and also suitable for living , like the blue lobster which is a mutation of the regular american lobster
June 29, 2010 at 4:41 am #100348
To cut a long story short. The link between Amino acids and DNA/RNA is completely arbitrary, and there is no reason that it should be what it is. Except that all life evolved from a single line of organism, our Last Common Unknown Ancestor (LUCA). So this is a case of historical contingency: the choice was not obvious, but once it was made, it was almost impossible to come back, and we are stuck with that.
IIRC some biologists have actually manufactured bacteria with modified tRNA so they do have a modified genetic code, that (my memory is hazy on the subject) are coding for non conventional amino-acids in proteins. Quite cool, Although not really useful.
As for a mutation that would have this effect it is quite unlikely (although probably not impossible) mostly because it would either needs quite a lot of mutations or have so far reaching effects that it would very likely be detrimental
June 29, 2010 at 11:08 am #100349
but there are some examples in our world that proves that mutation can have this effect , aren’t there ?
like the example of the blue lobster i’ve mentioned in my previous post or the "Moss Rose" which produce flowers of different colors (caused by mutation) .
June 29, 2010 at 4:19 pm #100350
No. Your example is just a mutation in a protein, not a change in the genetic code.
To be clearer take this metaphor: proteins are the read aloud word of a text. Most mutations are just a change in one or few letter(s) in a word. Say a U becomes an I. If it happens in certain word, the change will be obvious, but the word can still be interpreted correctly, MUTATION become MITATION, on the other end it can change the word completely and make the organism unfit for life, take DUCK for example, if I was to mutate as described I would deserved to be banned 🙂 because the change of meaning makes for a completely different word. Those are the most common mutations and only have a local (limited to said protein) effect.
But mutations that would alter the genetic code, would be mutations that would alter not the words themselves, but the way all the words are read, say you know have to read every I as U. That would cause a major and far reaching change in your discourse, and probably make it hard to understand, if not completely impossible (change all I to a [K] sound, it might make things impossible to read. Hence the very low likelihood of a mutation at this very basic level, and its universal conservation.
June 29, 2010 at 5:52 pm #100351
so .. do you mean that in the examples that i’ve mentioned , the change in one or few letters in the genetic code would produce the same protein but with different properties (as making the organism’s color changed)???
(as the codons are being read correctly)
June 29, 2010 at 6:47 pm #100352
It appears that you are not clear about you basic biology. I suggest that you go on the tutorials of this website and clear your ideas. Or you can go on the bookshelf of the NCBI and read a bit more. This book has a very good reputation: Albert’s Molecular Biology of the Cell
And to answer your question, yes the mutations that you are describing are limited to one protein. And in some case a change in a protein, or its level of production can cause measurable and visible effect. The codons are read correctly, it is just that one codon was changed to something else making a different protein. But you would not say that there was a change in the genetic code (i.e the codons are translated as they always have) but that there was a (point) mutation.
June 29, 2010 at 7:37 pm #100361mithParticipant
Are you asking whether there are benign mutations?
June 29, 2010 at 9:46 pm #100362
now i understand , your last illustration made a bit clearer and I Took your last two words (Point Mutation) and googled it so i read some articles about that point mutation , Missense mutation and Synonymous substitution and these made it very clear …. thnx for the book btw and thnx for your time 🙂
No , I know that there are benign mutations in our world , my question is (after putting it in a better form as i’ve learned some new concepts in the discussion above) :
"A specific species has a specific combination of genetic letters (nucleobases) , can a new combination of the genetic letters (in which some letters are replaced with others) produce a new individual of the same species that is suitable for living ?"
please , share with your opinion 🙂
June 29, 2010 at 11:27 pm #100363koleanParticipantquote truthSeeker:
I personally would call these new individual of the same species that is suitable for living –
July 2, 2010 at 7:45 pm #100380ApoptizzleParticipant
I am pretty sure that mitochondrial DNA follows a genetic code variation that differs from what is considered the universal genetic code of most organisms – but I admittedly know know much about that specifically, I just remember it from a class I was in. Mitochondria most likely came to be by one cell engulfing another (the mitochondria), so that could be a sort of proof-of-concept example of an "organism" that worked following a different genetic code.
July 2, 2010 at 9:49 pm #100382
July 19, 2010 at 3:57 am #100596HobbleParticipant
If you were to take a genetic code and completely re-arrange it, it would probably be very unlikely to produce a viable organism. Every organism’s DNA has been crafted after millions of years of alterations and mutations due to various conditions. To take the DNA of a chicken, mix it together with other parts, and expect to get a fire-breathing dragon, or even a viable microbe, is very complicated….
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