"1. Some proteins are made by creating sub-assemblies first, then putting the pre-fab parts together, rather than cranking out a protein ab initio one amino acid at a time.
The details of how THAT process happened one mutation at a time would be pretty interesting :-)"
Something funny here. All proteins are built one amino acid at a time. If these proteins are subunits of a larger structure (often an enzyme) then the assembly occurs after the subunits (which are proteins) are fully formed.
"2. Some proteins are cranked out one amino acid at a time, but according to one of your earlier posts, intermediate proteins come along (like scaffolding while constructing a skyscraper) to stabilize the intermediate structure."
The helper proteins, called "chaperones" operate while the growing protein is still attached to the ribosome to prevent improper or irreversible incorrect folding.
"This might lead one to think of a "chicken and the egg" conodrum, in which the cell needsthe protein which is being assembled one amino acid at a time, but without the stabilizing protein coming along at the right time, the energetically preferred conformation of the protein being assembled is not one biologically useful to the cell.
So (at first blush) one of two things needs to happen:
a) the cell "makes do" with some protein or other which happens to be laying around, in order to stabilize the being-built protein--presumably over time and generations the structure of the stabilizing protein changes to get better at its job--but not so much that it starts screwing up its original function. (I know, lotsa hand-waving here...)"
This would be a standard evolutionary model and certainly much more likely than the following which assumes that there is purpose and a future goal identified at the molecular level.
"or
b) the cell has to custom make the stabilizing protein first, before it tries to build the other protein, and just happens to get the size, shape, abundance of the stabilizing protein right, even before it is used.
Curiouser and curiouser, Bunter mine."
Facts are stubborn things - Lord Peter
or, if you prefer:
You know my methods, Watson - LP
8-)
Something funny here. All proteins are built one amino acid at a time. If these proteins are subunits of a larger structure (often an enzyme) then the assembly occurs after the subunits (which are proteins) are fully formed.
Slight miscommunication here...that is my point. Has anyone worked out the details of how random mutations tell the cell to take what had hitherto isolated subunits, and start constructing THEM into a larger structure. (The A & B subunits of hemoglobin, for example...)
Thanks for picking up the Wimsey reference; one of my favorite authors. Have you noticed all of the Alice in Wonderland and Shakespeare references sprinked throughout the dialogue ?
Cheers!