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Thread: An evolution revolution

  1. #16
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    so my grand kids are gonna be born irie? niiiice

  2. #17
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    well, if there's a gene that codes for irie, & an epigenetic change has turned it on (or the opposite, that there's a mechanism which inhibits the production of irie, and that inhibition has been turned off) & it's a heritable change, then yes, Zhao, there is indeed a chance that your kids could be born irie. keep in mind that it's also dependent on the irie allele from your partner, & environmental factors. and I have to caution you that the mechanisms by which irie is produced or inhibited are - almost certainly - poorly understood.

  3. #18
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    Quote Originally Posted by Mr. Tea View Post
    Srsly...

    Hard to do a punnett square for eye color, tho.

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    Quote Originally Posted by padraig (u.s.) View Post
    I have also been doing this stuff all semester.



    meiosis is a part of human sexual reproduction, or at least the precursor - it's the formation of the gametes (i.e., sperm or egg, depending) which will eventually fuse during fertilization to form a zygote. as nomad alluded to, crossing over is more the exchange of entire genes (or alleles) than a remixing of the primary DNA sequence, which would be more in the realm of mutation. one important thing to remember is that coding DNA only makes up ~1.5% of the human genome, so a lot of times you're just swapping around non-coding stuff (tho a fair portion of that has other functions, usually something to do w/regulation). when genes are swapped, there's ways that you can actually measure they physical distance between them on the chromosome, depending on how often the traits they code for are expressed in a population.

    & to your original point - you're correct, epigenetics are a more of a corollary to Darwin - it goes w/o saying that none of this would give Richard Dawkins a fit as the author of that stupid article suggests - than a refutation. what defines epigenetic is that there is an alteration w/no change to the primary DNA sequence, usually involves some kind of change to the actual structure of the chromosome, i.e. DNA methylation (gene silencing) or modifications to the histones in nucleosomes. where it gets tricky is all the mutual effects that different things have on each other - that's molecular biology, there's a million things & most of them are acting on each other somehow & it can be a real bastard to figure out what's doing what to what. a lot of it's not that well understood. I guess the big idea is that people thought to alter gene expression you had to alter the DNA sequence & then epigentics came along & was like "no, there's this kooky back door, check it out." that's another biology,thing, there's not all hard & fast rules & equations like physics - I mean, we have to follow rules (most of them made up by physicists), but a lot of times if you ask a biologist a question s/he'll be like "I don't know. no one knows."

    anyway, epigenetics has all kinds of cool potential applications. take medicine - for cancer, say, if you could figure to out a way to induce epigenetic changes in cancer cells, or reverse the ones that they induce, some means of getting the cancer cells to recognize molecular signals that tell them to stop dividing &/or go into cell death (apoptosis), then you'd have a cure for cancer w/o such deleterious side effects (granted, easier said than done). or just understanding the role that epigenetic changes play in the etiology of various diseases.
    It's funny you say that about physics, I have biology professor who, whenever you ask him a question he can't answer, he just says, "it's a physics thing", even when it clearly isn't, as a joke.

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    well yeah, for example all the biochemical reactions in the body have obey the laws of thermodynamics. all bodies have to obey some kind of mechanics, whether classical or quantum (& I know special relativity lurks somewhere in there as well). biology doesn't really have the laws in the same sense that chemistry & physics do, but we make use of their laws in biology.

    I read a story about this professor of neurobiology at Princeton - apparently he was originally going to become a physicist. as an undergrad at Caltech, he was taking a mechanics class & another course in molecular & cellular bio. he went up to the physics prof w/some question & the prof was like "oh yeah that's already been thought of" & wrote down a bunch of equations on a sheet. then he went to his bio professor & asked dude a question about something with synapses, can't remember what, & the bio guy, in classic fashion, said "I have no f**king clue." upon which the Princeton guy decided to switch fields.
    Last edited by padraig (u.s.); 02-04-2010 at 09:05 PM.

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    Quote Originally Posted by padraig (u.s.) View Post
    well yeah, for example all the biochemical reactions in the body have obey the laws of thermodynamics. all bodies have to obey some kind of mechanics, whether classical or quantum (& I know special relativity lurks somewhere in there as well). biology doesn't really have the laws in the same sense that chemistry & physics do, but we make use of their laws in biology.

    I read a story about this professor of neurobiology at Princeton - apparently he was originally going to become a physicist. as an undergrad at Caltech, he was taking a mechanics class & another course in molecular & cellular bio. he went up to the physics prof w/some question & the prof was like "oh yeah that's already been thought of" & wrote down a bunch of equations on a sheet. then he went to his bio professor & asked dude a question about something with synapses, can't remember what, & the bio guy, in classic fashion, said "I have no f**king clue." upon which the Princeton guy decided to switch fields.
    Linus Pauling, maybe? Nevermind....didn't catch the link before...

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    Cheers Padraig, that's some great stuff there, thanks a lot.

    Interesting points re. physics vs. biology - I can see the appeal of both the hard-n-fast rigour of physics (obviously) and the, I dunno, "mushiness" of biology, the huge profusion of phenomena even the field's experts can't claim to begin to understand. Whereas in physics (other than in the outer theoretical reaches of cosmology/field theory/particle physics) I think people are mainly filling in the little gaps in our knowledge within well-established paradigms, rather than venturing out into the great unknown.

    This discussion reminds me of a physicist called George Zweig - who independently proposed the quark hypothesis back in the '60s, although it was Murray Gell-Mann's version that won the Nobel - who left particle physics and then did pioneering work on the physiological basis of hearing and how sound signals are transmitted down the auditory nerve. Interesting career change, anyway. Roger Penrose's forays into 'quantum consciousness' are pretty out-there, but it remains to be seen how much of it is testable...
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    Quote Originally Posted by Mr. Tea View Post
    Cheers Padraig, that's some great stuff there, thanks a lot.

    Interesting points re. physics vs. biology - I can see the appeal of both the hard-n-fast rigour of physics (obviously) and the, I dunno, "mushiness" of biology, the huge profusion of phenomena even the field's experts can't claim to begin to understand. Whereas in physics (other than in the outer theoretical reaches of cosmology/field theory/particle physics) I think people are mainly filling in the little gaps in our knowledge within well-established paradigms, rather than venturing out into the great unknown.

    This discussion reminds me of a physicist called George Zweig - who independently proposed the quark hypothesis back in the '60s, although it was Murray Gell-Mann's version that won the Nobel - who left particle physics and then did pioneering work on the physiological basis of hearing and how sound signals are transmitted down the auditory nerve. Interesting career change, anyway. Roger Penrose's forays into 'quantum consciousness' are pretty out-there, but it remains to be seen how much of it is testable...
    The downsides to being a biologist versus a physicist are

    1) physics, sort of like proverbial "rocket science", gets more awe and respect, based on the fact that more people fail high school physics

    2) the smell of the fucking autoclave

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    This is kind of unrelated to the thread but MIT has a bunch of really good lecture videos up.

    Eric Lander
    , who is known for his role in sequencing the human genome and who's a good teacher to boot, has a bunch of neurobio lectures on there.

    There are some good chemistry ones up too but those are hard to get anything from if you dont have any background.

  10. #25
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    Quote Originally Posted by nomadthethird View Post
    The downsides to being a biologist versus a physicist are

    1) physics, sort of like proverbial "rocket science", gets more awe and respect, based on the fact that more people fail high school physics
    In fairness, I think it's very easy to teach physics badly. Or tricky to teach it well, at least.

    The funny thing is, I'm sure rocket science isn't actually particularly tricky (these days I mean, not in the '40s/'50s when it was being developed). Rocket science isn't exactly rocket science, in other words. Or rather, rocket science isn't exactly orbifold cohomology.
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    Quote Originally Posted by Mr. Tea View Post
    In fairness, I think it's very easy to teach physics badly. Or tricky to teach it well, at least.

    The funny thing is, I'm sure rocket science isn't actually particularly tricky (these days I mean, not in the '40s/'50s when it was being developed). Rocket science isn't exactly rocket science, in other words. Or rather, rocket science isn't exactly orbifold cohomology.
    Physics is also counterintuitive, even more so than a lot of biological concepts (which are more counterintuitive than people would assume, even though the calculations are generally trivial).

    There's this one kid in my program who's pre-med and also interested in neurology. He's Asian and really good at math, and we're in all the same classes, so we study together all the time. In chemistry right now we're doing thermodynamics, building on thermochemistry from last semester. For some reason this he just can not understand that an exothermic system has a negative charge so the deltaS of the surroundings has a positive one (after the double negative in the formula corrects itself). I'm sure you know which formula I mean, it's one of the simple one that's based on q-rev/T, I think it's deltaSsurr=-deltaHsys/T. Yesterday we went over that for like a half hour while he tried to argue that this equation was a stupid way to formulate that. (Usually in bio we use Gibb's Free energy equation...) He generally beats my grades in math but I beat him in chemistry, because for some reason he's good at following rules but bad at conceptualizing things.

    It's weird when someone is generally very good at math but still can't get physics. I have to take physics and it worries me when one of the smartest kids at my school doesn't get some of this stuff right off the bat.

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    Quote Originally Posted by nomadthethird View Post
    He generally beats my grades in math but I beat him in chemistry, because for some reason he's good at following rules but bad at conceptualizing things.
    my lab partner in chemistry - where again, I think I'm in the same class (i.e., second semester of General Chemistry) as you - is an engineering student. he's taking, I think, Differential Equations right now & is generally like 100x time better than me at math, but I'm absolutely slaughtering him in this class, I think he's barely pulling a C. I mean, the math for chemistry (at this level, at least) isn't really complicated, just algebra. it's more about being able not only to conceptualize, but also to apply the concepts. I don't know if there's that same level of application in physics, which seems more purely theoretical. like, if I see something on a chemistry test I don't understand at first, I can usually logic it out as long as I have a general familiarity with the background material.

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    Quote Originally Posted by padraig (u.s.) View Post
    my lab partner in chemistry - where again, I think I'm in the same class (i.e., second semester of General Chemistry) as you - is an engineering student. he's taking, I think, Differential Equations right now & is generally like 100x time better than me at math, but I'm absolutely slaughtering him in this class, I think he's barely pulling a C. I mean, the math for chemistry (at this level, at least) isn't really complicated, just algebra. it's more about being able not only to conceptualize, but also to apply the concepts. I don't know if there's that same level of application in physics, which seems more purely theoretical. like, if I see something on a chemistry test I don't understand at first, I can usually logic it out as long as I have a general familiarity with the background material.
    I love chemistry...my lab partner this semester is a complete slacker who goes on facebook on his phone the whole time and whines at me to hurry up. We had a 100 on most labs till he completely messed up one of those resin titrations by pouring in an extra 50ml of HCl through the buret. I was annoyed but it wasn't worth starting over...

    I have an easier time with chem calculations in lecture, sometimes the labs are harder to figure out. It's never hard math, but it sometimes it takes a while to figure out which equations to apply where. Still fun...although I'm getting sick of uv spectrophotometry...

    Taking orgo next semester, but biochem and p chem is when it gets really fun.
    Last edited by nomadthethird; 04-04-2010 at 10:33 PM.

  14. #29
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    99% sure you don't need p chem for med school. well unless you're majoring in chemistry, although I thought you already had a B.A. (in like English or Philosophy or something) and were just doing the year+ of required sciences. also pretty sure you don't need biochem, although it seems a more relevant - & interesting - class to take.

    I was planning on just the year of general & the year of organic, tho I could see myself taking a biochemistry course if I had the chance (i.e. the time) to do it.

    also your pm box is full.

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    Quote Originally Posted by padraig (u.s.) View Post
    99% sure you don't need p chem for med school. well unless you're majoring in chemistry, although I thought you already had a B.A. (in like English or Philosophy or something) and were just doing the year+ of required sciences. also pretty sure you don't need biochem, although it seems a more relevant - & interesting - class to take.

    I was planning on just the year of general & the year of organic, tho I could see myself taking a biochemistry course if I had the chance (i.e. the time) to do it.

    also your pm box is full.
    Oh you definitely don't need P chem...

    But biochem is a big help if you have time to take it. I'm going to take 3 years and just get the BA. I figure I might as well-- they just asked me to be in the biology honor society. And I want to do some kind of lame research project. Maybe even with the chem dept instead of bio.

    My advisor tells me to get an MD/PhD because he thinks I would like research. If I do that, I'll have two BAs, two MAs, an MD, and a PhD. But then, apparently they really need practicing doctors now too. It'll all depend on what schools I get into.

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