The ecoli one right?
The Common Ancestry Thread
by cantleave 271 Replies latest members adult
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tornapart
Sorry again! I see reading on that Ticker has been there and done that! However judging by the response he got I'm not sure I even want to enter an opinion at all!!
I'll just quietly read on and leave it at that I think. It is very interesting.
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jgnat
PSacramento
- Creatures with thin/fine fur, medium fur, and thick fur migrate in to hot and cold climates.
- Creatures with thin fur do not prosper in the colder climate, and die out.
- Creatures with thick fur do not prosper in the hot climate, and die out.
- Presto chango, we have thick furred creatures in cold climates, and thin furred in hot.
I have a girlfriend from South Africa who had an American Eskimo dog as a child. All she remembers is the poor thing huddled by the air conditioner, in the shade, and burrowing a cool burrow for itself. Believe me, these dogs are a lot more lively in their native environment!
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EntirelyPossible
jgnat, you have a PM.
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cofty
Ok, you say that mutations just happen but why do they just happen?
Try copying a sequence of 3 billion letters without error.
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frankiespeakin
What causes DNA mutation:
http://learn.genetics.utah.edu/archive/sloozeworm/mutationbg.html
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cofty
I think its really helpful to understand the connections between DNA code - amino acids and protein molecules to grasp this.
There is some stuff on it earlier in the thread.
The key thing about a protein molecule is its physical shape. It is made of amino acids that can be compared to little oddly shaped magnets that fit together in interesting ways.
The shapes on the surface of some proteins that we call enzymes allow other molecules to fit together.
Think about a cell as being like a chemical lab where somebody has smashed all the jars and mixed the contents together. Nothing will actually happen unless the right enzyme is present to introduce chemicals to each other. Different enzymes are produced by different types of cell depending on which genes are switched on.
An enzyme might start off as a very inefficient one but subsequent mutations cause one amino acid in the sequence to be replaced for another causing it to fit better. Over many generations natural selection refines the shape of the enzyme until it works effectively.
Evolution is a step-by-step process. The genius of natural selection is that it works like a ratchet. Tiny improvements are secured and built on.
There are a number of different 3 letter sequences that will code for the same amino acid and countless amino acid sequences that will produce the same shaped protein. Lots of mutations result in no change in the phenotype. Comparing those sequences provides compelling evidence of common ancestry.
Evolution is a step-by-step process. The genius of natural selection is that it works like a ratchet. Tiny improvements are secured and built on.
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PSacramento
So, if I am getting this right, something in the environment or a mistake in cell coying cause a trait to develop, thick fur for example, regardless of where the animal already is. Because of that trait the animal finds a better environment for itself ( migrates).
That is what happens and NOT:
Environmental factors cause the cells to mutate to better dapr and survive in those conditons.
Correct?
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jgnat
A ratchet - for this technically challenged girl - turns the bolt in only one direction, right? So if I were to use this analogy correctly, once a more efficient enzyme construction is encoded, we don't go back?
I wonder about that African carniverous plant that seems to self-select to the shortest genome possible. What advantage might there be for that? Speedier procreation?
It traps protzoa in its corkscrew leaves. No roots.
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jgnat
PSacramento: Because of that trait the animal finds a better environment for itself (migrates).
Or dies. Or fails to have offspring before dying. Or has fewer pups than it's thicker-furred cousins.
Lots of creatures show a fair bit of variation in their offspring; lighter and darker markings, for instance. Sometimes the environment favors one over the other, but the species retains the variation. This makes the species adaptable to changing conditions.
