Noguru,
I'm using the first definition of arbitrary:
determined by chance, whim, or impulse, and not by necessity, reason, or principle. I could make due with the trimming "not determined by principle."
Rereading my previous post, I understand how the statement "
Creating a functional protein, on the other hand, is the exact opposite of arbitrary," led to some of your questions. Actually, that statement does a rather poor job of conveying the idea I was trying to get across.
Rather, what I'm trying to say is that a protein must meet specific criteria in order to be functional. It's primary, secondary, tertiary, and (possibly) quaternary structures must all work together with it's biochemical surroundings so as to "do" something, and that in accordance with physical-chemical law, i.e. without divine intervention. I guess it's kind of like a jig-saw puzzle. The protein just has to "fit." It may not need to be a razor sharp fit, but it can't be a square peg trying to fit in a round hole. (Yet another "loose analogy" not to be to "under the microscope." I guess you could put a square peg in a round hole if it were small enough. Slight variation: a square piston-head would not function very well in a combustion engine with round piston-holes (whatever they're called.) And what if an engine "devolved" to creating a brittle piston-shaft which broke upon use. It would break, rendering the engine useless. Not good.)
noguru said:
Are you saying that natural selection understands this concept arbitrary
Are you asking me if I anthropomorphize the concept of natural selection in a wooden literal sense? I'm not sure what you're asking me here, NoGuru.
and only allows the creation of protiens through means that are not arbitrary?
I'm not so much speaking to the means by which the new protein is created, but rather to the nature of the new protein. In order to be functional within the cell, it has to "fit" its surroundings somehow, and one would think that it would carry out a function at least similar to its predecessor protein. Consider the following, written by Douglas J. Futuyama.
Over the course of vertebrate evolution, gene duplication has given rise to a family of hemoglobin genes that have diverged in function. The hemoglobin of the lamprey, a primitive jawless vertebrate, consists of a single protein chain (a monomer), encoded by a single gene. In jawed vertebrates such as fishes and mammals, hemoglobin is a tetramer: an aggregate of four chains of two types (alpha and beta), encoded by two genes with related sequences. This tetramer has a cooperative oxygen-binding capacity not available to the lamprey. In salmon, quadruple copies of the beta gene, differing slightly in sequence, yield four types of hemoglobin with different, adaptive oxygen-loading properties.1 In mammals, successive duplications of the beta gene gave rise to the gamma and epsilon chains, which characterize the hemoglobin of the fetus and early embryo respectively, and enhance uptake of oxygen from the mother.
Source
Imagine the mutation had
not produced functional proteins. The organisms carrying these mutated genes would simply die. They wouldn't pass along their seed. They wouldn't be "naturally selected." The genetic mutation and subsequent protein would warrant the label "not good."
Or is it genetic variation that has a guideline of not creating protiens through means that are not arbitrary?
The "means" of protein synthesis is governed by highly specific processes (not arbitrary). I'm not sure if I'm addressing your question. I find it somewhat vague.
Hope I made my position a little more clear.
SS