Protein Folding: A problem for neoDarwinism?

[bob b]

PlastikBudda wants to talk about "protein folding" so I am starting a new thread for that purpose. To start we give a general description:

Protein folding
From Wikipedia, the free encyclopedia

Protein folding is the physical process by which a polypeptide [protein] folds into its characteristic three-dimensional structure [1]. Each protein begins as a polypeptide, translated from a sequence of mRNA as a linear chain of amino acids. This polypeptide lacks any developed three-dimensional structure (the left hand side of the neighboring figure). However each amino acid in the chain can be thought of having certain 'gross' chemical features. These may be hydrophobic, hydrophilic, or electrically charged, for example. These interact with each other and their surroundings in the cell to produce a well-defined, three dimensional shape, the folded protein (the right hand side of the figure), known as the native state. The resulting three-dimensional structure is determined by the sequence of the amino acids[2]. The mechanism of protein folding is not completely understood.

http://en.wikipedia.org/wiki/Protein_folding

 

[rexlunae]

Ok, so where's the problem for evolution?

 

[bob b]

Ok, so where's the problem for evolution?

Not all possible DNA sequences will yield a sequence of amino acids that will fold.

If a sequence of amino acids does not fold it will be discarded by the cellular "garbage collector" machines.

Problem #1 is then "how did cells come up with a series of proteins which allowed the DNA/RNA/protein interlocked system to be generated"?

 

[rexlunae]

Not all possible DNA sequences will yield a sequence of amino acids that will fold.

And the problem is...? A DNA sequence which proves immediately fatal will be removed from the population by natural selection immediately.

Problem #1 is then "how did cells come up with a series of proteins which allowed the DNA/RNA/protein interlocked system to be generated"?

I still don't see the problem you are getting at. Are you talking about the origin of life, or something that occurs during its diversification?

 

[JustinFoldsFive]

Hallelujah!

 

[bob b]

And the problem is...? A DNA sequence which proves immediately fatal will be removed from the population by natural selection immediately.

Which seems to imply that the process could never have gotten started in the first place.

I still don't see the problem you are getting at. Are you talking about the origin of life, or something that occurs during its diversification?

Correct me if I am wrong, but doesn't common descent say that first life started with a single cell?

If so did that first cell include the DNA/RNA/ protein interlocked system or not?

If not then it would appear that evolution should address how the DNA/RNA/ protein interlocked system evolved.

 

[rexlunae]

Which seems to imply that the process could never have gotten started in the first place.

Well, the simple answer is that, as you know, the theory of evolution is not a theory of the origin of life, so it does not present a problem for Darwinism. This question is out of scope for evolution.

As for prohibiting any sort of naturalistic explanation for the origin of life, which is probably what you should have asked about at first, I don't see why it would. Just because "not all possible DNA sequences" are viable does not mean that there are none that are.

But since there is no current theory of the origin of life (that I'm aware of), you've jumped the gun a bit trying to refute it.

Correct me if I am wrong, but doesn't common descent say that first life started with a single cell?

No. A common ancestor, yes, but not necessarily a cell. I find it hard to believe that there would be any cells prior to some sort of genetic molecule, be it DNA, RNA, or something simpler, as your comment seemed to imply there would be.

If so did that first cell include the DNA/RNA/ protein interlocked system or not?

The first cell, probably. The first life (i.e. self-replicator), I don't know.

 

[pleasedtomeetme]

Which seems to imply that the process could never have gotten started in the first place.

But you said that "Not all possible DNA sequences will yield a sequence of amino acids that will fold." This would mean that some DNA sequences will yield a sequence of amino acids that will fold.

 

[PlastikBuddha]

PlastikBudda wants to talk about "protein folding" so I am starting a new thread for that purpose. To start we give a general description:

Protein folding
From Wikipedia, the free encyclopedia

Protein folding is the physical process by which a polypeptide [protein] folds into its characteristic three-dimensional structure [1]. Each protein begins as a polypeptide, translated from a sequence of mRNA as a linear chain of amino acids. This polypeptide lacks any developed three-dimensional structure (the left hand side of the neighboring figure). However each amino acid in the chain can be thought of having certain 'gross' chemical features. These may be hydrophobic, hydrophilic, or electrically charged, for example. These interact with each other and their surroundings in the cell to produce a well-defined, three dimensional shape, the folded protein (the right hand side of the figure), known as the native state. The resulting three-dimensional structure is determined by the sequence of the amino acids[2]. The mechanism of protein folding is not completely understood.

http://en.wikipedia.org/wiki/Protein_folding

So yet again your best evidence is that we don't currently know how something could have happened therefore it didn't happen? Patheitc.

 

[bob b]

But you said that "Not all possible DNA sequences will yield a sequence of amino acids that will fold." This would mean that some DNA sequences will yield a sequence of amino acids that will fold.

Of course. amino acid sequences coded by DNA do exist which fold and hence have use in lifeforms.

One key question would be: "how many of all possible sequences do fold versus how many do not".

 

[rexlunae]

Of course. amino acid sequences coded by DNA do exist which fold and hence have use in lifeforms.

One key question would be: "how many of all possible sequences do fold versus how many do not".

While it may be an interesting question, I don't see the problem for neodarwinism. Could you identify what the problem is clearly please?