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Author Topic:   Evolution Simplified
kuresu
Member (Idle past 2512 days)
Posts: 2544
From: boulder, colorado
Joined: 03-24-2006


Message 69 of 170 (310047)
05-07-2006 5:00 PM
Reply to: Message 58 by Hyroglyphx
05-07-2006 1:54 PM


Re: The heart of the matter.
The problem is, I can't think of one instance in where cancer, Down Syndrome, or Cystic Fibrosis benefitted anyone in any way.
cancer isn't beneficial, that's true. Down syndrome isn't benficial, that's true. But there are several disorders and mistakes that are beneficial.
Why do you think Africa has such a high rate of sickle-cell anemia? It helps them survive malaria, a disease that is quite prevalent there.
Why do you think Europe has such a high rate of cystic fibrosis? It helps them survie a disease (typhoid? its somewhere in my bio notes, but where in all three hundred pages I don't know).
If they survive longer, they get more chances to reproduce.
As to the rest of your post, what about transitional fossils?

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kuresu
Member (Idle past 2512 days)
Posts: 2544
From: boulder, colorado
Joined: 03-24-2006


Message 74 of 170 (310631)
05-09-2006 10:55 PM
Reply to: Message 72 by DrFrost
05-09-2006 8:00 PM


RE: Evolution Simplified
as soon as earth could possibly support life as we know it, there it was! This raises a lot of very interesting questions
it either means that life gets started quite easily, or that someone stepped in. considering that right now we cannot prove (or disprove the second), and that abiogenesis is looking like a real answer, then perhaps life does get started easily.
Hmm, mayhaps we are not so unique after all.
Chirop has already pointed out the confusion you have over what ToE is. No need to beat that horse again.

All a man's knowledge comes from his experiences

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kuresu
Member (Idle past 2512 days)
Posts: 2544
From: boulder, colorado
Joined: 03-24-2006


Message 88 of 170 (310909)
05-10-2006 10:36 PM
Reply to: Message 87 by robinrohan
05-10-2006 8:31 PM


Re:
true. the thousands of beetles that have yet to be discovered. The untold thousands of new species of microscopic bacteria.
It's all population growth curve. My ecology background is quite limited, but from what I understand, every population has an intial, slow increase in numbers, followed by exponential growth, at which point it exceeds the limit of the habitat and the numbers level off and there is a state of equilibrium.
This equilibrium point is determined by the number of organisms in the population that the habitat can support. We do not know, as far as I've heard, when humans will quit our exponential growth curve and begin to level off. And if we make it into the stars, who knows if we'll ever level off.

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kuresu
Member (Idle past 2512 days)
Posts: 2544
From: boulder, colorado
Joined: 03-24-2006


Message 93 of 170 (311071)
05-11-2006 4:08 PM
Reply to: Message 92 by robinrohan
05-11-2006 3:53 PM


Re: Generalizations
Is this inevitable? Perhaps all mutations could be neutral? Are mutations themselves inevitable?
look at the mutations made easy thread by Quetz.
In that mutations do happen, you could say that they are inevitable. It is inevitable that the DNA replication mistake repair enzymes won't catch all mistakes.
It's a mutation that's responsible for cystic fibrosis and sickle cell anemia. It's also reponsible for well over one hundred genetic diseases. IOW, not all mutations are neutral, some are even horrendous.
As to fact #5, it's true. SCA, if homozygous recessive, will kill you if not treated, and it does this is roughly five years. No reproduction possible at that young an age. Not having the homozygous condition will give you a better chance to reproduce.

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kuresu
Member (Idle past 2512 days)
Posts: 2544
From: boulder, colorado
Joined: 03-24-2006


Message 103 of 170 (311230)
05-11-2006 9:58 PM
Reply to: Message 102 by robinrohan
05-11-2006 7:07 PM


Re: Generalizations
all I can say is "duh!".
Look at my SCA example

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kuresu
Member (Idle past 2512 days)
Posts: 2544
From: boulder, colorado
Joined: 03-24-2006


Message 110 of 170 (311300)
05-12-2006 12:00 AM
Reply to: Message 109 by robinrohan
05-11-2006 11:48 PM


Re: Generalizations
actually, they do happen often. Just a ball park figure, but if every gene had, say, ten base pairs, and we have roughly twenty thousand genes, that's 200000. And at ten per gene, that's only three amino acids per protein, and most proteins in our body are much, much longer.
Then, how many times do our cells divide? plenty, so even if there were only 200000 base pairs, there are trillions of cells in the body.
The mutations that are important are those in gametic cells, as those are the ones passed on to the offpsring. Guys produce millions of sprem cells weekly, if not daily. Think of how many base pairs total there are in that number. Point is, mutations happen, and happen often.

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kuresu
Member (Idle past 2512 days)
Posts: 2544
From: boulder, colorado
Joined: 03-24-2006


Message 123 of 170 (311411)
05-12-2006 12:28 PM
Reply to: Message 121 by robinrohan
05-12-2006 12:14 PM


I'm not sure just how many genes control eye color in humans, but if we assume that thee are just two, B for brown and b for blue. We know that blue eyes are recessive, so in order to be expressed, the person must be homozygous recessive. here's a punnet square to help demonstrate: the cross BB * bb
being "BB" is homozygous dominant.
being "bb" is homozygous recessive.
all the offspring (the ones in the boxes) are Bb and this is known as being heterozygous. no offspring will have blue eyes, but will have
the trait. if the cross is Bb * bb, half of the offspring will express the trait for blue eyes, and all will carry it. Try this cross on your own, using the same format of the square below.

__|_b__|__b__|
B | Bb | Bb |
__|____|_____|
B | Bb | Bb |
__|____|_____|

abe: cleaned up the format of the post.
abe2: punnet squares are evil to format.
abe3: i give up formatting it
This message has been edited by kuresu, 05-12-2006 12:30 PM
This message has been edited by kuresu, 05-12-2006 12:32 PM
This message has been edited by kuresu, 05-12-2006 12:32 PM
This message has been edited by AdminAsgara, 05-12-2006 11:46 AM
This message has been edited by AdminAsgara, 05-12-2006 11:47 AM

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kuresu
Member (Idle past 2512 days)
Posts: 2544
From: boulder, colorado
Joined: 03-24-2006


Message 130 of 170 (311458)
05-12-2006 3:56 PM
Reply to: Message 127 by robinrohan
05-12-2006 3:23 PM


Re: Heritable traits
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.
That was the case in the example I used. Try a cross between two heterozygotes, in this case that would be Bb * Bb. the resutls are:
BB, Bb, Bb, bb.
BB is homozygous dominant, and neither carries the blue-eye gene or expresses it. Bb is heterozygous, and while not expressing blue eyes they do carry that gene. bb is homozygous reccesive and does carry the gene as well as express it.
As to the second part of what you said, that much is true.

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kuresu
Member (Idle past 2512 days)
Posts: 2544
From: boulder, colorado
Joined: 03-24-2006


Message 134 of 170 (311476)
05-12-2006 4:18 PM
Reply to: Message 132 by robinrohan
05-12-2006 4:11 PM


Re: Heritable traits
quote:
so it's very possible for a "positive" trait to disappear within one generation
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. Now, if those offsrping carrying the gene were killed before they could pass on the new gene, and they were the only ones with the mutation that lead to that gene, then yes, it is possible to wipe out a positive trait in a single generation.

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kuresu
Member (Idle past 2512 days)
Posts: 2544
From: boulder, colorado
Joined: 03-24-2006


Message 136 of 170 (311485)
05-12-2006 4:31 PM
Reply to: Message 135 by robinrohan
05-12-2006 4:29 PM


Re: Heritable traits
Unless for some reason all the offspring were born homozygous dominant in the example we've been using, the answer is yes.

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kuresu
Member (Idle past 2512 days)
Posts: 2544
From: boulder, colorado
Joined: 03-24-2006


Message 137 of 170 (311486)
05-12-2006 4:37 PM
Reply to: Message 133 by robinrohan
05-12-2006 4:15 PM


Re: Clarifying sexual recombination
any mutations that have evolutionary significance occur during conception
conception, if I remeber correclty, is the process of sperm and egg meeting and combining their genetic material. mutations do happen here, but EZscience wasn't talking about those. However, these mutations do have "evolutionary significance".
you may have misunderstood EZscience when he said:
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
he mentioned the mutations that happen during gametic formation. These are the ones that happen while you body is making sperm or eggs (depending on your sex). The mutations from this process are the ones passed on, because gametes, not body cells, are used to form zygotes. These, then, have "evolutionary significance".
Keep in mind, if something is capable of budding (like hydra), or growing from clippings (like many plants) this isn't always the case.

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kuresu
Member (Idle past 2512 days)
Posts: 2544
From: boulder, colorado
Joined: 03-24-2006


Message 141 of 170 (311493)
05-12-2006 5:14 PM
Reply to: Message 140 by robinrohan
05-12-2006 5:06 PM


Re: Heritable traits
you may be taking my comment a bit out of context, or something like that. We have assumed that blue eyes are reccesive in the example. in order for it to be expressed, the person must be "bb". However, it could be that the person is "Bb", in which case he still carries the gene. a right partner isn't needed, unless you mean someone of the opposite sex in your species (for mating, sexes are required). The person carrying the gene just has to mate in order to pass it down, barring the unlikely scenario that you quoted that I gave.

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kuresu
Member (Idle past 2512 days)
Posts: 2544
From: boulder, colorado
Joined: 03-24-2006


Message 143 of 170 (311500)
05-12-2006 5:23 PM
Reply to: Message 142 by robinrohan
05-12-2006 5:18 PM


Re: Heritable traits
I think my post was more to dispel the need for the "right partner" in order to pass on the gene. That wasn't quite clear in my last post.
let me try again. the right partner is not needed in order to pass on the gene, that person just has to mate.

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kuresu
Member (Idle past 2512 days)
Posts: 2544
From: boulder, colorado
Joined: 03-24-2006


Message 145 of 170 (311506)
05-12-2006 5:31 PM
Reply to: Message 144 by robinrohan
05-12-2006 5:25 PM


Re: Heritable traits
it has everything to do with the parents. my objection was when you said that in order to pass on the gene the person with it needed to mate with the "right person". Which is why I said that the person carrying the blue eye gene just needed to mate in order to pass it on.

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kuresu
Member (Idle past 2512 days)
Posts: 2544
From: boulder, colorado
Joined: 03-24-2006


Message 147 of 170 (311510)
05-12-2006 5:38 PM
Reply to: Message 140 by robinrohan
05-12-2006 5:06 PM


Re: Heritable traits
not only this appearance of a positive trait but also that individual has to mate with the right partner
you and I seem to be misunderstanding each other, and the post I'm replying to is where it's starts, I think.
in the quote, do you mean by appearance the phenotypical expression of the gene? phenotype is the physical characteristics of the organism. Genotype is the genetic characteristics of the organism. genotype controls phenotype.

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Replies to this message:
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