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Author | Topic: Evolution Simplified | |||||||||||||||||||||||
robinrohan Inactive Member |
As it stands, the rate for mutagenesis in mammalian nuclear DNA, in terms of single-point substitutions, is 1 per every 3.6 billion base pair replications, according to my wife's phylogenetics text. I'm not sure what that 7th word means, but it sounds like mutation doesn't happen very often.
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robinrohan Inactive Member |
1) hundreds of times every second in your skin as new skin cells and hair are grown and the lining of your digestive tract is replaced, plus 2) thousands of times per second as your bone marrow replicates and differentiates new cells to replace the contents of your blood; plus 3) 1.5 million times a day as your testes produce sperm (assuming you're a man), plus 4) whatever assorted other cell division is going on in your body. So, for every act of cell division per day that comes to (millions), we should expect the new sequence of DNA to differ from the old one in 1 or 2 different places. So are mutations frequent or not?
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robinrohan Inactive Member |
If my post didn't answer your question, I guess I don't know what you mean by "frequent." We estimate that any one human being has between 5 and 500 mutations. Every single human. Would you characterize that as "frequent"? I'd say that it's "sufficient." I mean in the ones that matter as regards evolution--the ones that get passed on. Say, in your standard litter of pups. -------------------------------------------------------------------------------- This message has been edited by robinrohan, 05-11-2006 11:08 PM
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robinrohan Inactive Member |
I would estimate that each pup would have between 5 and 500 mutations, individually. Just a question: Mutation is not the same thing as imperfect replication, is it? I thought that meant that the female and male combinations would result in a baby that did not look exactly like the mamma or the papa due to the combination.
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robinrohan Inactive Member |
So the term "imperfect replication" does not mean the same thing as "sexual recombination"?
One does get mixed signals on this forum.
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robinrohan Inactive Member |
6. Conclusion: From 3, 4, and 5 we can conclude that organisms with the traits that make them more likely to survive and reproduce will produce offspring with those traits, Are traits always passed on to the next generation? Suppose there was a person born with blue eyes for the first time and suppose these blue eyes were helpful to survival and reproduction. Does this mean that this trait is automatically going to be passed on? Could his or her offspring have brown eyes?
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robinrohan Inactive Member |
In my opinion you have asked good questions on this topic. You're about the only one who thinks so.
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robinrohan Inactive Member |
If the basis of his blue eyes was genetic then a classical genetic analysis like Kuresu has done will tell you the likelihood of the gene being passed on I thought he meant that the trait was definitely going to be passed on, but it might be recessive, which I assume means that it might turn up in the phenotype in later generations.
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robinrohan Inactive Member |
Actually, what you are talking about is simply shared parental genetic representation in the offspring of diploid species. I didn't get all that, but what I want to know is if every baby is mutated.
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robinrohan Inactive Member |
Perhaps most species are increasing but haven't been doing so for very long, or perhaps the rate of increase is so small we don't notice it. Is that theoretically possible?
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robinrohan Inactive Member |
BB is homozygous dominant, and neither carries the blue-eye gene or expresses it OK, so it's very possible for a "positive" trait to disappear within one generation, in which case it would have no evolutionary significance, correct? But we could even say that it could extend for a few generations and then disappear. But I guess the more generations it got passed down, the more likely it would be to become permanent (since more indivduals would possess it), other conditions being equal.
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robinrohan Inactive Member |
Since mutation occurs randomly, albeit not with equal probability on all portions of the genome, the odds are that we all carry a number of mutations that occurred during the formation of the gametes that gave rise to us when they formed a zygote. So any mutations that have evolutionary significance occur during conception, when the strand from one double helix meshes with a strand from that of the mate, and what happens is that they don't all mesh properly?
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robinrohan Inactive Member |
Not entirely ture. As in the case of the blue-eye example that you started. Given the condition that I assumed (blue is reccesive), it would get passed down to the offspring, based off of statistical probability So some of the offspring MUST have the trait, just not all of them?
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robinrohan Inactive Member |
These are the ones that happen while you body is making sperm or eggs (depending on your sex). OK, I got it now. You're right; I didn't understand what EZscience was saying. It's confusing. There seem to be so many different types of mutation. This message has been edited by robinrohan, 05-12-2006 04:01 PM
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robinrohan Inactive Member |
Unless for some reason all the offspring were born homozygous dominant in the example we've been using, the answer is yes. OK, then it's not an absolute. It's possible, though perhaps unlikely, that a positive trait would appear and not be passed down. So what you need is not only this appearance of a positive trait but also that individual has to mate with the right partner. Otherwise evolution will not occur.
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