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Author Topic:   Are Point Mutations problematic for ToE?
Percy
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Posts: 22504
From: New Hampshire
Joined: 12-23-2000
Member Rating: 4.9


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Message 5 of 36 (584027)
09-29-2010 8:41 PM
Reply to: Message 1 by seanfhear
09-29-2010 7:03 PM


Here's what I think is the strongest argument against point mutations only being able to decrease information.
We start by assuming that the premise that point mutations can only decrease information is true. Take as an example this short segment of DNA:
...TACGCC...
A random mutation occurs in this segment of DNA with the fourth nucleotide changing from G to T, decreasing the amount of information:
...TACTCC...
Now some number of generations later another random mutation occurs in the exact same spot with T changing to G, again decreasing the amount of information:
...TACGCC...
We know that the third sequence must have less information than the first because by the law of transitivity if the second sequence has less information than the first, and the third has less than the second, then the third sequence must contain less information than the first. But the first and third sequences are identical and must therefore contain an identical amount of information, so it is obviously impossible for the third sequence to contain less information than the first, and so by the law of contradiction the starting premise that point mutations can only decrease information must be false.
--Percy

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Percy
Member
Posts: 22504
From: New Hampshire
Joined: 12-23-2000
Member Rating: 4.9


Message 25 of 36 (584076)
09-30-2010 4:11 AM
Reply to: Message 18 by seanfhear
09-29-2010 11:06 PM


seanfhear writes:
Would it be appropriate to assume a trait for an allele as an example and to speculate what could be a possible change in the function or structure of an organism if information was lost? Can you think of a simple example?
One good example is vitamin C synthesis in humans. A single point mutation, in this case a deletion, caused a frame shift in the GULO gene responsible for the synthesis of vitamin C. A frame shift is what happens when a single nucleotide is inserted or deleted.
A frame shift works like this. Say you have this simple nucleotide sequence that I've divided into triplets:
TAG / CAT / GCC
Now let's perform a single nucleotide deletion, let's say the 2nd nucleotide gets deleted. We're now left with this:
TAC / ATG / CC
The loss of a single nucleotide has caused the framing of codons to shift, hence the name frame shift mutation. TAG has become TAC, CAT has become ATG, and GCC has become an incomplete codon CC. As you can see, a single nucleotide deletion has the potential to completely change the codon sequences and thereby the protein it is responsible for.
This is in essence what happened somewhere in the distant evolutionary ancestry of apes. A frame shift mutation in the GULO gene responsible for the synthesis of vitamin C experienced the deletion of a single nucleotide that resulted in a premature stop codon. In humans vitamin C synthesis never completes because of the premature stop codon. We have to get all our vitamin C from what we eat.
Here's a comparison of the same subsequence of the rat and human GULO gene. To make it easier to interpret I've included the human sequence twice, once with a dash where the cytosine nucleotide was, and then again with the frame shift:
[face=Lucida Console]Rat:   GTA / GAG / GTG / CGC / TTC / ACC / CGA / GGC / GAT / GAC / ATT / CTG / CTG / AGC / CCC
Human: GTG / GGG / GTA / CGC / TTC / ACC / TGG / AG- / GAT / GAC / ATC / CTA / CTG / AGC / CCC (without frame shift)
Human: GTG / GGG / GTA / CGC / TTC / ACC / TGG / AGG / ATG / ACA / TCC / TAC / TGA / GCC / CC  (with frame shift)
    Single cytosine nucleotide deletion------------^[/face]
Sorry it's so wide.
--Percy
Edited by Percy, : Reduce width by using less of the nucleotide sequence.
Edited by Percy, : Typo.

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Percy
Member
Posts: 22504
From: New Hampshire
Joined: 12-23-2000
Member Rating: 4.9


Message 36 of 36 (584290)
10-01-2010 6:41 AM
Reply to: Message 35 by subbie
09-30-2010 10:32 PM


Re: Population or Individual?
Other creationist beliefs that get in the way of their understanding:
  • Anything random can only be bad.
  • Anything bad must decrease information.
  • Anything good must increase information.
All three are so obviously false, falsifying counterexamples so easy to come by, that I'll stop here.
--Percy
Edited by Percy, : Grammar.

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