ybbor said:
but then you can only work with a pre-existing protein and only add an amino acid or two, which would severely limit the amount of changes you can produce. you wouldn't get much variation froma few amino acid changes. also, a base deletion or substitution wouldn't add more DNA.
What are you talking about? You don't work with pre-existing proteins, but rather with pre-existing nucleobases: cytosine, guanine, adenine, and thymine. A base-substitution could result in a change from useless DNA that doesn't actually code for anything (which there is a lot of) to DNA that codes for a protein. The same can happen with a base deletion. You need not add more DNA to have more information. Of course, simple addition still occurs often enough to add nucleobases to the DNA to lead to an increase in overall DNA, which would be selected for because it, once again, increases variation, which in turn enhances the ability to survive of the species. Consider also that you have
billions (the oldest fossilized life is 3.5 billion years old) for DNA to be added and you will realize that it's not that remarkable that we have so much DNA. There are actually plenty of organisms with more DNA than humans, but more DNA does not necessarily mean more advanced. Not all of it codes for something.
ybbor said:
all sexual reproduction does is move the problem to the other organism
What problem are you talking about? Sexual reproduction allows for new combination of genes, increasing variation, and is selected for as variation increases the survivability of a species. Plus, the errors that can occur in sexual reproduction can increase the amount of DNA in an organism, if that's what you're concerned with. For instance, if there's a problem in spermatogenesis or oogenesis (which can very well happen)\ during
either meiosis I or meiosis II, cells with excess chromosomes can result; a polyploid organism (3n or even 4n) can result, creating a new species. Although there is no
new genetic information, the extra information results in an organism of a different species, and as its mutations will likely be different from the mother species, can result to a completely new species. This happens especially in plants. There are for example, many types of polyploid wheat.
ybbor said:
I mean how did we get more DNA/chromosomes (yeah, that was poorly worded, but i meant both).
I just explained them both (
please make sure you quote well, too, btw. I almost missed this).
I'm going to go ahead and answer your responses to Perfection, too.
ybbor said:
well less DNA still raises the frame shift problem.
What frame shift problem? Base insertion is not the only type of mutation (not even close)! If a deleterious frame shift occurs, then the organism will simply die; that is natural selection. Only the beneficial frame shifts or mutations (which can increase the amount of DNA) will be passed on.
ybbor said:
expand. dose bacteris A get new genetic information from bacteria B? Dose Bacteria A get infromation from B and B gets gen. info from A? is there duplication? are the same genes excahnged?
Wiki can explain it better than I can.
http://en.wikipedia.org/wiki/Bacterial_conjugation
There are other methods that unicellular organisms can take up new DNA, by thew way. For instance, in Transformation, it can simply take up DNA or RNA from the environment and incorporate it; viral transduction allows DNA from one bacteria cell to be passed to another by way of a virus (that does not necessarily destroy its host).
http://en.wikipedia.org/wiki/Transduction_(genetics)
http://en.wikipedia.org/wiki/Transformation_(genetics)
ybbor said:
I didn't say all frame shift mutations were bad, i said they exponteially made it harder to produce a beneficial variation. because you have to make sure the mutation in hundereds or thousands of amino acids is beneficial, as opposed to a substitution where just one is muatated and you can select for it more easily.
Now, I'm not sure if you understand natural selection.
If the frame shift is bad, then the cell will simply die. Only good mutations are preserved over time. It doesn't matter how many bad frame shifts occur. So long as there are still beneficial ones occuring, evolution will still occur.
ybbor said:
but if that duplicated gene codes for the same protein, wouldn't they undergo the same selction process and change littlw, only making improvements to the existing gene? also, if most mutations are harmful, wouldn't this double the likelyhood of mutation; and thus the likelihood of death?
Of course they can only make improvements to the existing genes (how would they make improvements to nonexistent genes?). Polyploid species are not the same as their immediate ancestor, even if they have double the genes. Just like a man who has an extra Y chromosome is not the same as a man with just one Y chromosome. Double the mutations, by the way, might double the number of genes that could mutate (not the probability, though), but that is not necessarily bad, as it would create more variation. Not all mutations are bad. The new species might evolve faster and therefore become more suited to its environment than the original species because of the increased mutation. Remember, only good mutations are kept. The mutations that cause death do not continue in the species.