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    :confused: am i feeling out of my depth! :rolleyes:

    i cant even keep up with the physics discussion, and I did a level physics!!!
    anyone want to discuss somethimg i can get my head round, like art?
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    (Original post by crana)
    say you could have two parents (pretend they only have 4, non linked gene loci):
    AABBCCDD and aabbccdd - they have no alleles in common, their combinations are as different as you can get
    True but this will never happen in reality, only on paper.
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    (Original post by Squishy)
    I thought type A blood had antibodies that attacked B antigens, etc. So it is important. But eh, the bio part of science lost me a long time ago. Just like the phys side will be losing me soon.
    Or rather stuff than isn't A, naturally including B.

    (Original post by Squishy)
    I thought type A blood had antibodies that attacked B antigens, etc. So it is important. But eh, the bio part of science lost me a long time ago. Just like the phys side will be losing me soon.
    I had a look in my book and you are right: O has A and B antibodies, A has B amtibodies etc as you said.

    It seemed strange to me because I was wondering why on earth would an O person have antibodies against A and B antigens if they have never come into contact with the other person's immune system.. but my book says that it's a very special case where (hope Ive got this right) the antibodies aren't made to be against the blood-group-antigens, they are made to be against bacteria, and it just happens that they also work against the blood group antigens!!

    So I wonder if people with AB blood are more prone to certain infections than O people....!
    rosie

    (Original post by Faboba)
    True but this will never happen in reality, only on paper.
    well of COURSE it won't, but to discuss things like this we have to use vastly simplified models......!
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    Is it me or have we hijacked the thread a little?

    Don't know how reliable this page is, but it claims that different blood types should have different diets, and there is some difference in how vulnerable they are to certain diseases. I suppose it makes sense.

    (Original post by KHL)
    likely i wasn't really talking about alleles, sorry... now that you put it that way, it does seem quite confusing.

    okay, forget about alleles for the time being... just think of each gene's identity as being derived from the source, i.e. mum-gene or dad-gene. because we all have 2 sets of genes, there are theoretically 2 possible mum-genes, and 2 possible dad-genes. whether or not a person is homozygotic is irrelevant to our current discussion.
    well, it isn't, because if a parent is homozygous at a particular locus then their children will have an 100% chance of sharing that allele at that locus.

    (Original post by KHL)
    now, we have a mum-gene and a dad-gene for each gene locus in our cells. chances are, that a sibling will have the same mum-gene or dad-gene is 50% for each gene. (they could just as easily get the other possible mum- or dad-gene)

    so, if you averaged across all the 30000 or so gene loci in our cells, we'd probably share about 15000 or so of the EXACT same genes (i.e. same source, mum or dad) as a sibling. (i.e. 50%, because the other 50% are probably copies of the other possible mum- or dad- gene that we lack in our cells, having only received one of two possible copies from each parent).
    But it doesn't matter where your alleles come from. They are no more exactly-the-same because they come from the same parent than they are if one comes from each parent but they are the same allele. The source of the allele doesn't matter.

    (Original post by KHL)
    that said, considering that at most gene loci, the human species share common alleles, 99% of all the genes, and thus 99% of the differences arising from different sources (mum and dad), probably become irrelevant since they will both be the same allele anyway, if only from different parents.
    Er, yes, that is what I have been trying to say for quite some time...so do you agree that if what you have just said is true, then it follows from that that siblings must have >50% of their alleles in common.

    (Original post by KHL)
    this is only significant when dealing with the gene loci where there are different alleles, but because of random assortment, the percentages still hold - i.e. at gene loci where there are different alleles possible, a sibling will still share approximately 50% of your alleles, simply because they got it from the same source! and if it happens that there are other different alleles available from your parents, then chances are the other 50% will be these different alleles, if not, then this problem becomes irrelevant again. :rolleyes:

    (we are ignoring mutations, crossing over, etc.) ...
    No, I still disagree. In situations where one allele is overwhelmingly common for this gene and others are extremely rare - and this is still "at gene loci where there are different alleles possible" - in almost all families you and your sibling will share 100% of your alleles at this locus. Random assortment makes no difference in this case. Since this situation applies to very many of our genes, I cannot really see how you can say it "becomes irrelevant again"?

    (Original post by KHL)
    oh, and two sisters are not morelikely to share alleles.
    If you actually read what I said and hold back on the italics for a second, I said: "two sisters are likely to share more alleles than two brothers". This isn't the same as what you said.

    (Original post by KHL)
    final point: all these things about alleles and gene loci, you must keep in mind that they are statistical, i.e. applies only to large numbers of gene loci. single gene loci follow mendelian genetics, and are usually pretty cut and dried. 30000 gene loci, on the other hand...
    thanks for that.

    Rosie

    (Original post by Squishy)
    Is it me or have we hijacked the thread a little?

    Don't know how reliable this page is, but it claims that different blood types should have different diets, and there is some difference in how vulnerable they are to certain diseases. I suppose it makes sense.
    Interesting, but actually it doesn't claim this. If you read through the whole thing the author actually goes onto rubbish a large part of these claims. The bit at the top with Type/Diet is the author describing what these claims are - they are attributed to someone else.
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    This thread is really beginning to scare me now.
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    (Original post by crana)
    Interesting, but actually it doesn't claim this. If you read through the whole thing the author actually goes onto rubbish a large part of these claims. The bit at the top with Type/Diet is the author describing what these claims are - they are attributed to someone else.
    Yeah, sorry, I just searched for a page on Peter D'Adamo...I've read his stuff before and it sounded a strange (since I've never followed his guidelines and I'm healthy enough). I'm not surprised his theories are being criticised though.
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    (Original post by Acaila)
    This thread is really beginning to scare me now.
    Don't be scared. SuperShiny will protect you

    i suggest we change what we are saying to

    "on average, a person will share 50% more alleles with (have 50% more alleles in common with) their sibling than with an unrelated person"

    (yes i know everyone is interrelated eventually, but i think we could agree on "unrelated" meaning not a close relative or something)

    anyone else happy to go with this, or anyone want to refine it mor?
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    (Original post by shiny)
    Don't be scared. SuperShiny will protect you
    Yay! {hides behind SuperShiny - Superhero in Pink}
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    OMG....i leave you alone for a day.....and you all start being intellectual again!!

    I forgot this thread consist mainly of natscis....and whilst i've done my best to forget about science...it seems i will never escape it

    Having said that..i do find the blood group antibodies thing interesting...what i don't get is...if you put say...A blood into O person's system....then the A antibodies in the blood attack the new blood cells right?

    However.....if you put O blood into A person....why doesn't the A antibodies in the new blood attack the blood alread present in the system?? :confused:

    G
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    Ahhh, Aragorn, you have returned. And they lost me too!

    (Original post by gzftan)
    Having said that..i do find the blood group antibodies thing interesting...what i don't get is...if you put say...A blood into O person's system....then the A antibodies in the blood attack the new blood cells right?

    However.....if you put O blood into A person....why doesn't the A antibodies in the new blood attack the blood alread present in the system?? :confused:

    G
    You know, that's a good question. Do they remove the antibodies from the O blood before they give it?
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    (Original post by Squishy)
    You know, that's a good question. Do they remove the antibodies from the O blood before they give it?
    I don't think so..if they do...that's the first i've ever heard of it! :eek:

    G
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    (Original post by gzftan)
    I don't think so..if they do...that's the first i've ever heard of it! :eek:

    G
    Oh, here we go.

    The antibodies in the donated blood are quickly diluted and don't cause any trouble. It's only the antibodies in the blood of the recipient that matter, because they are present in large numbers and will destroy any incoming blood cells that have a 'foreign' antigen.
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    (Original post by Squishy)
    Oh, here we go.
    Ah...the fog has lifted....i geddit it now

    Cheers.

    G
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    By the way...where's your sig from?
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    (Original post by crana)
    p35
    "For example, for the universe to exist as it does requires that hydrogen be converted to helium...in a way that converts seven one-thousandths of its mass to energy"

    I thought you couldn't convert mass into energy - they were two different measurements of the same thing.
    I notice some other people have tried to answer the other point...

    My understanding is that mass and energy are interchangeable but I don't have a problem with the statement.

    There are energy levels within nuclei which are roughly equivalent to energy levels electrons can possess. Also, within the nucleus of helium-4, say, the protons and neutrons are further down this potential energy well than they would be in, say, two deuterium atoms. This results in the overall mass of the matter being greater on the left hand side of an equation like:

    D + T ---> He + n

    The "lost energy" (equal to the binding energy of the reverse reaction) is given out in particles (neutrinos and anti-neutrinos, I think) and the speed of the neutron. These leptons (if it is these particles) have zero rest mass. Yes, they have energy and are buzzing around the universe at speeds getting up towards that of light. They therefore have some virtual mass. If a set of neutrino traffic lights turn red, however, our little friends run out of all their energy. Lower an atom to practically absolute zero and it will still have mass as it possesses mass independent to its speed (something to do with that Scarlet Pimpernel of particle physics, the Higgs Boson).

    I'm very interested in this sort of stuff and I was upset and annoyed at my mate Dave for going away to Spain after he finished his theoretical physics PhD at Southampton! We used to stay up till all hours getting utterly wasted and talking about stuff like that (I did more listening!)

    I can't claim to have much knowledge, just interest I await everyone saying I'm wrong!
 
 
 
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