Darwinbots Forum
General => Biology => Topic started by: Zelos on April 29, 2005, 02:45:06 PM
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we humans have 46 chromosones, where the last ones are the sex chromosones. X and Y. Guys have XY and girsl XX. Scientist have created a few mouses that have XX and still is males, they have never had any Y chromosone in them. The scientist added a gene from the Y chromosone into the X chromosone and then they got 1 XX mouse who was a male. many did of course not survive
if you cant read swedish then there is no idea for you to ask me to show it. maybe you can instant find it on the net on english
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Biologically speaking, males are almost females. That is, females are the default template, and males are simply a modification of this. Male niples are a good example of this.
SO: what's my point? While you can probably find one or a handful of genes that make a XX animal develop a penis and outer genitalia, it will probably be sterile, and may still have a euteris (sp?).
Hermaphrodites are a good example of what I'm talking about. Just because you find a gene that makes something have a penis doesn't make it male. And just because you can get something with a vagina doesn't make it female. The sexes are more subtle are complicated than that.
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if you ask me what decieds what sex something is its decieded mostly by whats ur part of the reproduction, if you give DNA then ur a male, if you take DNA then ur a female, if you do both ur a Hermaphrodites. but still I think its still amazing that a change in that gene can make you a female, or maybe even a Hermaphrodites.
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There is certainly nothing like that on front-page news of scientific web-sites. Sometimes these "news" come out of really nowhere, just some pretty old finding which is over-stated by a journalist.
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I didnt find this on a website. it was in a science paper adn they have yet never had wrong. soo I dont see any reason they would have it now.
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Again, it's not a single gene alone that determines sex. Changing any single gene can give interesting results if that gene is important to development of something. But the effects of genes are more subtle than you're giving them credit for.
Sex is not a switch between Male and Female. There isn't a magic gene that turns on the switch between the two.
Children are basically androgenous. Aside from genitalial differences, they're just about identical. When puberty hits, it's the hormones that really cause the differences between the sexes.
So if you want a 'magic bullet' that seperates the sexes, it's got to be estrogen (and the related hormones) and testosterone (and the realted hormones). But those come from the genitals, so they are only indirectly effected by the genes.
Again, the sexes are more subtle than you give them credit for.
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then how comes that they got a male that only had female chromosones?
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define male.
define female chromosomes.
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male=penis, can reproduce, deliver DNA to the female
female chromosones= XX
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I didnt find this on a website. it was in a science paper adn they have yet never had wrong. soo I dont see any reason they would have it now.
That's a suspicious statement right there, because real scientists aren't 'never wrong'. Real scientists make stupid mistakes all the time, that's why the publish papers. So others can show what the scientist got wrong so the scientist can revise and improve is hypothesis and experimental technique.
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male=penis, can reproduce, deliver DNA to the female
female chromosones= XX
1. Is a castrated man still a male? He can't produce sperm.
I think your female mouse with a penis is sterile. Like I said, a penis a male does not make. It takes more than that.
2. X is just a designation we use for the chromosome. It doesn't define the chromosome. Tell me exactly what it is that makes it an 'X' chromosome.
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ops, ive should have said, "ive never seen them have wrong yet" sorry my misstage
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its different if ur born sterile or if you become sterile. I think so atleast
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So if you're born sterile you're not a man anymore?
If you're born with no vagina but a nub about the size of a clitoris, are you male or female?
Again, more subtle than just black and white, male and female.
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How about the case of certain FISH (http://www.ptmsc.org/science/topics/fish_tales.htm) that are known to change sex completely.
The dominant male Clownfish Amphiprion percula (http://cooltech.iafrica.com/science/252988.htm) and many other reef fishes live in matriarchal societies consisting of a single dominant female, a smaller dominant male and a whole family of juvenile males that are incapable of sexual reproduction.
If the female dies then the dominant male changes sex to become the new dominant female and a new dominant male emerges from the ranks of the juveniles.
They are all a bunch of transexuals and not a plastic surgeon in sight. :D
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Found this (if you really want the site, okay... but I'd like to keep the forum more or less G rated...)
...glands were made in the womb before physical gender was determined (in the womb a baby goes through a stage where it is neither male or female, at this point has nipples gonads, which will develop into ovaries or testicles, and a small bump that will be either a clitoris or a penis).
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So if you find a gene that makes this nub develop into a penis, you may still have female genitalia. You're not a guy (but I guess you're not really a girl either.)
Point is, there's no '1 singel gene' that determines sex, because there's no '1 singel' thing that makes you male or female. It's a collection of physical and psychological (I mean brain chemistry) differences.
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Yeah, I just talked to my wife. She works on the mouse genetics, says she never heard of a single "sex" gene. It is really pretty close to how Nums put it: "sex" is hard to define and there is a lot of regulation going on.
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I think that if ur not born whit a reproduction organ, but have so it only look little like it, you are neither one of the sexes
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zelos, the point Nums was trying to make is that reproductive organs don't make "sex". You can have perfect reproductive organs, yet be unable to bear children, because your hormonal system is messed up. Alternatively, you may look like a perfect (fe)male, but have no normal reproductive organs. Finally, you can be a perfect (fe)male, but may die soon after birth. All of these are examples of different deffects that are caused by mutations in sex-related genes.
The thing is that "sex" is a very-very complex thing and it cannot be regulated by one gene. What most liekely happened was that the scientists found some gene that regulated one particular aspect of "sex" and the journalist did not think it was "hot enough", so (s)he changed it to "sex is decided by one gene". This happens every day, even with very serious newspapers and journals. I pretty much try to not read those sections at all, because all it does for me is it pisses me off :)
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I have read about cases of normal XY males becoming females because of the IQC (I think) of the X and Y chromosomes... the X chromosome having the DAX gene to make a human female and the Y chromosome having SRY to make them male. However, the X chromosome can obtain an extra DAX which makes them physically female when genetically male. I think I have all those crazy anagrams the right way round lol.