[quote]Raided wrote:
Mattlebee wrote:
No, the phenotype is the physical (overt) manifestation of the genotype. Environment is an additional factor.
Phenotype is the manifestation of genotype and environment. Those are the two factors for phenotype.[/quote]
Most of the definitions I find are like the following:
“Phenotype: This is the “outward, physical manifestation” of the organism. These are the physical parts, the sum of the atoms, molecules, macromolecules, cells, structures, metabolism, energy utilization, tissues, organs, reflexes and behaviors; anything that is part of the observable structure, function or behavior of a living organism.”
Environmental factors certainly affect the physical appearance, behaviour etc., but their effect is superimposed on the phenotype. In famine conditions people are shorter and thinner. That’s nothing to do with their genes and it’s not their phenotype.
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What do you think is the ultimate cause of all these things? The ultimate underlying cause is the sequence of nucleotides in your DNA. For each example you gave think about what the ultimate cause was.[/quote]
This is a “Guns don’t kill people, people kill people” sort of an argument.
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The view you have of genes as just a store of information is no longer the consensus opinion. As I’ve told you before read the Selfish Gene by Richard Dawkins and you’ll get up to date on current thought.[/quote]
You can’t convince me that a thirty year old book is more up to date than biochemistry textbooks published last year. What the human genome project has made clear is that the number of genes is less important for complex life than the interactions between them and their environment. There are entire fields of research investigating the effect of maternal diet on diseases that their children develop in later life. Genetic imprinting is the big thing in biology at the moment and is a phenomenon on top of the sequence of nucleotides you have. If anything the importance of genes has been depreciating.
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The purpose of DNA is not to supervise the building of bodies, if that was the case then why is there so much DNA that doesnt do anything. [/quote]
Copying errors during replication.
DNA doesn’t have a purpose. It’s a very stable molecule that can be used as a way of storing sequences of amino acids. It doesn’t replicate without external machinery to unravel it and align complementary nucleotides.
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The body is just a machine for carrying around DNA, organisms are just a shell. [/quote]
You certainly are a Dawkins advocate.
I see it more like a cell that accumulates useful genes is more likely to survive. Bacteria regularly swap genes with each other and those that get useful genes to add to their collection will prosper over those who have just the basic set. It’s now thought that one of the earliest aerobic cells prospered because it had a bigger toolkit than the specialized bacteria around it. When conditions changed (more oxygen) it could cope where the others couldn’t.
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You clearly know a bit about the red blood cell and its shape and why it doesn’t carry DNA. But where is ultimate source of its design. If it isnt the DNA you tell me where?[/quote]
The important thing you’re undervaluing is that cells are the building blocks of life. You start from a single cell that divides many times and under the influence of external stimuli the early cells differentiate into heart, skin, bone etc. cells. They all have exactly the same DNA in them, but they look and act very differently. What controls/defines these cells isn’t their DNA. Something else is controlling the DNA and thereby the proteins the cell expresses.
During the final stage of red blood cell development the nucleus and all its genes is ejected from the cell. Massive fail on the part of that DNA in terms of survival, but a big win for the efficient functioning of the organism. Of course, better blood means that other copies of the genes in the testes are more likely to be passed on, but to claim it’s all about genes surviving is too reductionist.
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And In the end it isn’t about the organism, the story is played out by genes, genes that cant think or plan they just are and they keep on replicating.[/quote]
The story is played out by cells and tissues. Genes are along for the ride, but can help out by giving an edge. In organisms where their physiology is so good that they are more or less immortal (and who only rarely reproduce) you can see complete domination of this long-lived organism over its short-lived rapidly replicating competitors, simply because rapid replication is only a good strategy when resources aren’t limited.