Evolution is a Fact #2 - DNA Functional Redundancy
In the first thread in this series we looked at how the same protein molecule can be assembled by many different sequences of amino acids.
We took the example of cytochrome C and saw that there are many times more possible sequences than atoms in the known universe. However the sequences in humans and chimps are identical, and as we look at species less closely related to us by evolution the more differences we find. This is very compelling evidence for common ancestry.
In this post we are going to look more closely at the DNA code behind those amino acid sequences.
The "language" of DNA is made up of just 4 "letters" - A,C,G and T.
Sequences of letters are read off in groups of 3 called codons.
ACGGCCTCGAATGCCTTC would be read as ACG GCC TCG AAT GCC TTC
If you do the maths you will see that there are 64 different codons or "words" that can be produced by this method.
A codon is comparable to the instructions for making one amino acid. There are a collection of 20 amino acids that living things can choose from to assemble proteins. (Actually a 21st can be assembled from the "stop" codon)
This is where the word redundancy comes in. There are 20 amino acids to be made but many more codons available.
It turns out that codons are often not too fussy about the third letter. If you want to make the amino acid alanine for example the codons GCT, GCC, GCA, or GCG will all do equally well.
So we can now look in more detail at proteins like cytochrome C. We said that the human version and the chimp version have identical sequences of amino acids. We can now ask whether those amino acids were made from identical bits of code.
They differ by 4 letters of code, that's a 1.2% difference.
When geneticists compare different species the very same picture emerges. The more distantly two species are related to each other in evolutionary history the larger the percentage of difference in DNA code that is used to build cytochrome C protein molecules - and yet they all do exactly the same job and can be substituted for each other in the lab.
There is no reasonable explanation for this apart from evolution from a common ancestor.
Here is a table of the relationship between codons and amino acids...
Good OP, cofty.
And if my memory serves me well, isn't methionine (Met) the initial amino acid made during protein synthesis?
I won't ask about the missing ink.
But can I ask a reasonable question about common ancestry?
Is a cabbage more closely related to a human or a worm?
In case that's too easy:
And is a rock related to any of them?
Why not a creator using the same tools? Seems to be more evidence of design than evolution
Is a cabbage more closely related to a human or a worm? - human & worm both belong to Kingdom Animalia; cabbage belongs to Kingdom Plantae.
is a rock related to any of them? - no.
if my memory serves me well, isn't methionine (Met) the initial amino acid made during protein synthesis? - LUHE
I'm going to take your word for that.
Why not a creator using the same tools? Seems to be more evidence of design than evolution - Shadow
Theistic evolution holds that evolution is the tool god used to make the world. An important factor though is that design is NOT evidence of god. There is nothing in the living world that requires a designer.
It's a subtle but important difference from creationism. You seem to have muddled the two.
Kenneth Miller and Francis Collins hold to theistic evolution and they are both opposed to intelligent deisgn
Its funny that somebody "disliked" a table of codons.
My thoughts are my own. I don't feel the need to quote a rabbi for every thing I say.
So biological systems must be much simpler than inanimate systems since a designer is never needed
Okay is a human more closely related to a cat or a dog?
Are you sure we're not related to rocks? Aren't we all stardust?
Dont I remember reading Dawkins say there were patterns on rocks on cliff faces and that's how the whole thing started maybe. If so then why not say we are related to rocks?
Deepak Chopra said this about evolution.
Darwin's theory of evolution is an enormous over-simplification. It's helpful if you want to connect the dots and understand the interrelatedness of life on the planet -- and it's simple enough to teach to children between recess and lunch. But it fails to capture the driving force and what's really going on.