Quick Questions, Short Answers - No Debate

Just a quick suggestion regarding the rating system. I have noticed that some people just go down the posts in a thread and, (or at least it appears) they cheer those posts they agree with and jeer those they disagree with regardless of quality of content. It ends up that creationists have a low score and evolutionists have a high score. I am sure that is not what you intend for the rating system.What I suggest is only being able to rate a post that you actively participate in. In other words, unless you respond to a post or a post is a response to you, you can not rate it. This may help the ratings to better reflect the quality of a member's posts.Perhaps a "like" button in addition to the rating button would allow non-participants to acknowledge a good reply without actually participating, but it would not affect the member rating.Just a thoughtHBD

And members who consistently make good, thoughtful and considerate posts. At least, as I see the purpose. Your probably right. I kinda like Coyote's suggestion in [MSG=252]. That way you wouldn't have indiscriminate jeering. Good, Better, Best. It could still be used as a popularity contest though. I am sure that's true. I was just kinda thinking that it would be nice to look at a members rating and have an idea of whether it would be worthwhile to enter into a debate with them or not; rather than whether they are creationist or evolutionist. But I guess it doesn't really take too long to figure that out by just responding to a few posts.HBDEdited by herebedragons, : corrected linkEdited by herebedragons, : corrected link again!

Actually, I like that idea.Maybe not "Post of the ..." that would imply only voting for one post? Maybe just good, better, best?

In addition to what Dr. A said, the replication of mtDNA is severely down regulated during embryogenesis which reduces the per cell copy number creating a mitochondrial bottleneck.This also serves to restrict the mitochondrial haplotypes that are eventually put into oocytes.Another thing to keep in mind is that the human mitochondrial genome is only about 17k bases as opposed to nuclear DNA which is about 3 billion bases. If the expected mutation rate for nuclear DNA is about 300 bases per generation, the expected mutation rate for mtDNA would be 0.0017 mutation per generation or 1 mutation every 588 generations. Of course, mtDNA mutation rates are higher than that for nDNA due to the less precise replication machinery and less redundancy in DNA repair mechanisms (some estimates are that the rate is 10x higher).This study empirically determined the mutation rate to be 3 mutation in 705 mtDNA transmissions:

quote:

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we sequenced the mtDNA control region in 272 individuals, who were related by a total of 705 mtDNA transmission events, from 26 large Icelandic pedigrees. Three base substitutions were observed, and the mutation rate across the two hypervariable regions was estimated to be 3/705 = .0043 per generation (95% confidence interval [CI] .00088—.013), or .32/site/1 million years (95% CI .065—.97).

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The Mutation Rate in the Human mtDNA Control RegionSo we would expect that most of the time the offspring would inherit the exact same mtDNA as the parent had.HBD

Oh, no problem Ned. I'll admit I can use "jargon" at times, the reason is that it is not "jargon" to me. To me the meaning of "down regulated" is just as obvious as "mutation" and neither term seems like "jargon" to me. So it can sometimes be difficult to know when a commonly used genetic term needs more explanation.When I read some of the physics threads, especially stuff on quantum physics and string theory, it is completely meaningless to me, gooblygook is the correct term I believe. But then again, I don't claim to have any knowledge about the subject matter nor am I especially inclined to try and understand the physics "jargon."ABE:I was going to respond in a different thread, but decided it was easier to just do it here. If the conversation needs to continue, we can move it then.The ovum, or egg, has a large number of mitochondria. But during embryogenesis, the replication of mitochondria is down regulated, meaning simply that they replicate very slowly rather than at a normal pace. As the blastocyst forms, the mitochondria are partitioned into the dividing cells. Because they are not replicating, the number of mitochondria in each cell is greatly reduced compared to the original ovum. Normally, the mitochondria would be replicating so that the number of mitochondria in each cell would remain constant (of course different cell types have differing numbers of mitochondria - some have higher energy requirements than others).The mitochondria don't begin replicating at a normal rate until I think gastrulation, when cells begin differentiating into different tissue types. By this time, the cell line that will develop into new oocytes will have a limited number of mitochondrial haplotypes. So even if there many haplotypes in the original egg, they have now been segregated into many cell lines and there will very few haplotypes (possibly only 1) that are passed on to the next generation. I'm not sure "wiped clean" would be accurate, instead just a relatively small number of mitochondria are funneled to new oocytes and so the number of different haplotypes being passed on to the next generation is limited. Also the mutations that will accumulate in the mitochondria that will be passed on to the next generation are only those that occur in the cell line leading to the reproductive cells. So we don't expect large numbers of mutations in each generation nor do expect to see significant numbers of haplotypes being passed on. More like it is a very reliable method of inheritance.HBDEdited by herebedragons, : No reason given.