BIOLOGY 103
FALL, 2003
FORUM 9

More on Genes, and How to Think About Them


Name:  Julia Wise
Username:  jdwise@brynmawr.edu
Subject:  race and heredity
Date:  2003-11-10 10:31:20
Message Id:  7175
Comments:
I think you can say there's no one gene for stuff like lactose intolerance, sickle cell anemia and such, but that doesn't mean it's not hereditary. When people first spread out over the world we got isolated into little clumps, so it makes sense that people from the same clumps would've shared traits. If you have kids with someone who has the same facial structure, skin color, etc (i.e. race) it makes sense that you might also share the same predisposition for sickle cell anemia because your ancestors came from the same clump, and your kids will have the same traits.
(It always seemed a little sketchy to me that in Star Trek, where society was so altruistic and advanced, all the people had clearly defined races/nationalities. Surely by then we'll have started mixing a little more?)
Name:  Brittany
Username:  Anonymous
Subject:  
Date:  2003-11-11 18:53:53
Message Id:  7212
Comments:
I want to lodge a rational disagreement with the idea that there is no specific gene for a specific order, such as (for example) sickle-cell anemia. Sure, there's no gene that will automatically jump up and slice red blood cells into little half-moons, but the gene produces a protein that does just that. So isn't the gene the origin of the disorder? How is this gene's defect *not* specifically linked to sickle-cell?

To steal an example from my recent debate tournament... imagine there's a box with a button. If you press this button, somewhere, someone you don't know will die. The argument is that pressing the button is the same as shooting the person in the head. The fact that you don't know him and his death can't be traced back to you is irrelevant. His death is still *your* responsibility.

It seems that genes work in the same way---only with genes, the proteins that produce disorders like sickle-cell create an easily-identifiable trail back to the defective gene. My point is, there *is* a specific gene (or at the very least, specific part of a gene) that causes disorders like sickle-cell. The fact that the gene wasn't created to cause sickle-cell is irrelevant; if it's shaped a certain way, it inevitably leads to the disorder. Thus, it's ultimately responsible for slicing those red blood cells into little half-moons. So it uses proteins as its medium to do this; so what? Saying it's the protein, and not the gene, that's responsible for the disorder is like saying it's the gun, not the criminal, that's responsible for the murder.


Name:  nomi kaim
Username:  nkaim@brynmawr.edu
Subject:  Genes vs. Proteins, and Diversity vs. Homogeneity
Date:  2003-11-11 20:07:35
Message Id:  7214
Comments:
Britanny, you have a very good point there. Disorders like sickle-cell ARE, ultimately, genetic, even if triggered by the environment. But remember that any disorder will be caused by not one genes but a whole series or sequence of genes interacting with each other. If one of the genes in this sequence is changed or absent, the sickle cell disorder (or any other disorder) will not manifest itself as such. For this reason, it is incorrect to refer to the "sickle cell genes." The "sickle cell gene combination" would be a bit closer....

Another thing I think you may be doing with your criminal/gene vs. gun/protein analogy is tying ethics too closely to pure, raw biology. Not that ethics are not useful in the study of science -- they often are -- but in this case, I think the analogy doesn't quite fit. The reason is that two people may have the exact same gene combination (let's say theyr'e identical twins) that codes for the sickle-cell-producing proteins, yet only one of them gets sickle cell anemia. Environmental factors -- originating outside of the body, then transferring their influence into the body and mind -- alter the proteins that are actually produced in one twin and allow that guy to get off scott free. Great! Now, the twin with the sickle cell disease is the only one people are worried about, because the other guy, predisposition or no predisposition, doesn't have the proteins for sickness and is going along just fine. It's the equivalent of us pardoning the criminal whose gun malfunctioned (environment interfered with normal functioning of gun when trigger pressed) which would be morally ridiculous ... a criminal is a criminal is a criminal! However, this genetic problem is not moral in that way, and it's the PROTEINS we care about more than the genes themselves because it is the PROTEINS that manifest themselves as the illness. What matters, as far as I'm concerned, is whether or not someone actually GETS sick -- and genetic predisposition is only one thing we can use to try to predict, and prevent, this. In other words, it isn't always necessary to get to the very "bottom" of the source of something -- sometimes, the most directly-linked and obvious cause is actually the most important.

Along the same lines, I think your "box-with-a-button" analogy is also too simple. Though parallels exist, of course, with genetics, it is NOT a specific gene that codes for a disorder, and the series of genes that does code for it can be taken in many combinations, all of which result in different proteins and different physiological manfestations. There is not, ever, just one "button," and that is why a simple trace-back from protein up to gene doesn't always work.

Okay ... this is so long already! But I was just thinking about life and the double-movement-struggle towards diversity and towards homogeneity. The way I see it (as of this evening) is this: the process of pure biological evolution tends toward SAMENESS. Natural selection intends to, eventually, destroy all who do not fit the perfect standard for their particular community, environment, and time. In fact, if only one environment existed on earth, only one species(not that this is possible with life!), the force of natural selection really WOULD cut out all diversity, eventually -- because it is true that, in a given environment and among a given species, there is ONE SPECIFIC TYPE SPECIMEN that is more "fit" or adapted to its conditions than any other! Well! Fortunatley for us, this will never happen. It will never happen because of the second great force, environment, which tends toward DIVERSITY. Environment includes physical location and ecology; it includes the chemical and physiological environments that cause genes to randomly mutate; it includes the cellular environment that causes gametes to recombine. The variations initiated by biological environments -- recombination, mutation, forms of "imperfectification," if you will -- are then supported and perpetuated by the ecological environments to which they are best suited. ...So natural selection's movement toward homogeneity is bound to fail because of the changing nature of living being's environments. This is all very long-winded, but I guess what I've just realized (dawn breaks on marble head!) is that life is NOT the only thing that is diverse, and, in fact, in order to BE and remain diverse, living things depend upon the great diversity of their environments. (Not that living things don't also change their environments ... it's a two-way road!) If you stuck us all in a place without any variety, it is a matter of course that we, too, would eventually become homogenous.


Name:  Brittany again.
Username:  Anonymous
Subject:  
Date:  2003-11-11 20:31:40
Message Id:  7216
Comments:
Naha, I can be combative too...

Good points, Nomi, but the reason I brought up sickle-cell anemia as an example is precisely that it is *not* a "gene combination." It's the single misfire of a single protein on a single gene (or gene pair, as they come in pairs, and the gene does require dominance to create the disorder). But there's only one gene that can cause sickle-cell; environmental factors can't. See, the protein that sickles the sickle-cell is actually a *part* of the RBC itself---it's not something you can inject into the blood to temporarily stave off the problem. You can't catch the disorder, or cure it; you can only inherit it. There's no way that one individual in a pair of identical twins could have it and the other could not. The same goes for Down syndrome. It can only be caused by an extra chromosome 21. Nothing else---not environmental factors, not outside agents---can cause it. These disorders, and others, *are* "boxes with buttons." Sure, not *all* disorders function this way. But sickle-cell, Down syndrome, and several others (especially sex-linked disorders!) definitely do. I guess my point is that, while in some cases you're right and you *can't* specifically link a gene to a disorder, in other cases, the relationship is crystal-clear, cause-and-effect, a single bullet from a single gun.

I also have to disagree with your discussion of the biological trend towards sameness. A single environment will never reduce its occupants to a single species. Life just can't exist that way---organisms feed off one another, utilize one another, form symbiotic relationships with one another. And say earth *did* have only one environment; that environment would still have "niches" that different organisms could fill. Look at the Sahara. You can't get a more homogenous environment than that, right? And yet the Sahara supports a wide variety of organisms, all exploiting different aspects of the Sahara's harsh environment. Diversity is as inherent to environment as it is to life. Even in an environment that *appears* to be the same throughout, organisms adapt to different aspects of that environment in their quest for survival.


Name:  Paul Grobstein
Username:  pgrobste@brynmawr.edu
Subject:  Science matters ... how?
Date:  2003-11-12 09:06:48
Message Id:  7223
Comments:
Don't wish to interrupt interesting discussion of how to think about genes, trust it will continue, but the New York Times Science Times yesterday seems to me quite relevant to our class conversations in a broader sense. Have a look at it? And I'd be interested in your reactions to the following reaction of my own ...

*************

It is appropriate, desirable, and indeed necessary to periodically examine the role that various institutions play in the broader human cultures of which they are a part ... and science in no exception. From this perspective, Science Times of 11 November 2003, and the lead article "Does Science Matter?" by William J. Broad and James Glanz, is very much to be welcomed.

At the same time, it is important to discriminate betweent those aspects of an institution that make it valuably unique in a culture and those that simply reflect the cultural commonalities that exert similar pressures on all cultural institutions. Science is far from the only institution asked by the culture "to resolve social ills". We ask that similarly of other quite different institutions - medical, political, economic, and religious - and it is not clear to me that the performance of science in this particular regard is dramatically any worse (or better) than any other institution in our culture. In this regard, I worry that Broad and Glanz (and the Science Times issue as a whole) might mislead readers by posing a set of benchmarks that might well be used for evaluating our culture as a whole but are not the appropriate ones for answering the specific question "Does Science Matter"?

The distinctive role that science has played in our culture, and can if it is valued continue to play, is not to resolve social (or individual) ills but rather to be the embodiment of permanent skepticism, of a persistant doubt about the validity of any given set of understandings reached by whatever means (including those of science itself). It is the insistence on doubting existing understandings, not the wish to eliminate humans ills nor to find "answers", that has always animated science and has always been the source of its power and successes.

Is that persistant skepticism, the perpetual unsettling of existing understandings, good for the culture of which science is a part? For humanity? That remains, of course, to be seen. The by-products of science have certainly contributed to alleviating some social ills but have also exacerbated or brought into being others. At the same time, a strong argument can be made that, on balance, human culture (like life itself) depends fundamentally on conceiving solutions to potential challenges before those challenges come into being. Doing so is what science is, distinctively, all about.

From this perspective, the fact that "two-thirds of the population believe that alternatives to Darwin's theory of evolution should be taught in public schools" is not an indication that science doesn't "matter" but rather an indication that it does. On a widespread basis, people are being provided with the products of skepticism, with alternative stories that haven't occured to them before and that are potentially relevant to future challenges. And I would argue that this is today occurring with unusual effectiveness in an array of areas of unprecedented scope, ranging from cosmological issues, to issues of the nature of human life, consciousness, and personal responsbility, to explorations of the place and meaning of humanity in the universe.

The key question, from my perspective, is not "Does Science Matter?" in terms of the standards we apply to all institutions in our culture but rather does science matter in terms of the distinctive role that it has to play in our culture? The answer, it seems to me, is demonstrably yes, and it is becoming even more yes as the decades and centuries go on. The remaining question, one that follows importantly from this, is whether our culture wants science to matter in the distinctive way it can and does. Here, I think, there is some grounds for concern, as evidenced by the recent shift in funding patterns from mostly public to mostly private and commercial support of research. I fear this reflects a misguided view of why science matters, one to which the Science Times issue could, however unintentionally, contribute. I hope not, because I suspect strongly that the future of humanity depends on our enthusiam for supporting the kinds of anticipations of change that will not occur without an institution committed to permanent skepticism.


Name:  su-lyn
Username:  spoon@hc
Subject:  Saharan diversity
Date:  2003-11-15 15:17:04
Message Id:  7263
Comments:

Nomi, I disagree with your point that there is "ONE SPECIFIC TYPE SPECIMEN that is more 'fit' or adapted to its conditions than any other". If we were talking about a comically simplified organism (say, a stick man) inhabiting a comically simplified environment, then the single-adaptive-peak might be a reasonable claim. But because each environment imposes a variety of pressures on each organism (in our Sahara example, high day time temperatures, freezing night time temperatures, locomotion over soft sand, etc.), adaptations are always a result of compromise. Because of this element of compromise, there exist multiple forms and multiple 'lifestyles' that work equally well. That is what accounts for the diversity that Brittany points out.

Allow me to bring up the example from my evolution class. A very simplified environment was modelled for plants that only required the organism to be adept at tackling one biological problem, with the solution resulting from the combination of only two factors. In our case, we might model an animal dealing with the high temperatures of the Sahara through different combinations of body size and body shape. In this environment, a few forms emerged as 'peaks' on what is known as the adaptive landscape (with peaks and valleys corresponding to fitness). These peaks were very 'high', very differentiated from the rest of the landscape i.e. no similar forms came quite as close to getting the job done.

But when the simulation was re-run such that the organism now had to tackle three different biological tasks (as above, high temperatures, freezing temperatures, locomotion), a different landscape emerged. There were far more peaks now, but at the same time they had been reduced to bumps in the landscape, such that the next best alternatives (of which there were many) might not really be so bad after all. As a result of the need to be 'decent' at all tasks, the organism cannot be perfectly fit at only one task. This forces compromise and, thus, diversity.

Name:  nancy
Username:  nevans@bmc
Subject:  genes
Date:  2003-11-16 18:10:03
Message Id:  7271
Comments:
This talk about genes for diseases such as sickle cell is interesting, and it leads me to wondering about genetic expression in other traits, and how we, as a society, seem to be moving towards a scientific explanations for things we don't tolerate well. The obvious example I am thinking of is homosexuality. There is constant talk of finding the "gay gene", as if finding a gene for something that is hard for society to digest will make people feel better. I think it would be interesting to locate such a gene, but the motives seem to be to use genetics to explain the behavior. Another example is obesity. The media overly valorizes thinness, and everyone knows the benefits of a healthy diet and exercise, yet the percentage of americans who can be classified as obese is constantly on the rise? My fear is that if we find a gene for an unhealthy condidtion such as obesity, people will feel as though they shoudlnt work to prevent it since it is genetically predispositioned.
Name:  Nomi
Username:  nkaim@brynmawr.edu
Subject:  
Date:  2003-11-16 19:42:50
Message Id:  7272
Comments:
Thanks to Brittany and Su-Lyn for clarifying some issues for me ... I agree. I must say I was really "mid-thought" when I wrote that last forum. To tell you the truth, it's actually quite a relief to find that I'm wrong (at least in some sense). I had myself scared there for a minute! -- trying to concvince myself -- almost fatalistic.

I thought Nancy had a very good point. She raises a difficult balance that people must strike between ACCEPTING something and becoming RECONCILED to it. We need, of course, to accept homosexuality and obesity, as well as any other characteristics, and to stop judging them. Judging does nothing. It's never a matter of "fault!" I think people are correct in looking for "the gene" behind these characteristics if they do so in an attempt to erase the concept of fault. On the other hand, fault should not exist in the first place, and there is really no need to "explain" or "justify" what simply IS.

...That is not to say there is a huge, essential difference between being homosexual and being obese. There is! Homosexuality doesn't hurt anybody (unless involved with some sort of abusive relationship, but that can happen anywhere). As such, homosexuality is not what we term "pathological" -- that it, it exists in the normal range, and we don't have to do anything about it! Obesity, on the other hand, is very dangerous, and so is pathological and SHOULD be changed, if possible. We should not become reconciled to being fat just because we might be able to explain it genetically! What I really want to say is, it's hard to strike this mental balance, to fight both ends of the blame-vs.-change battle. On the one hand, we don't want people to blame homosexuals, or the obese, for their conditions. On the other hand, we want the obsese to try to lose weight -- and to have them understand that their condition, unlike homosexuality, is physically dangerous. I believe it is a matter of erasing what is "morally objectionable" -- a useless social judgement to make, really -- and focusing on what is "personally or socially harmful." (So there go religious ideals -- out the window!)

I also want, before class tomorrow, to give my answer to the question about why cells have lower-limits for size. I think that, just as with upper limits, it is a practical, spatial reason. In this case, however, I think it has to do not with surface area but with molecular complexity. The smallest atom must still take up a certain amount of space. In order to perform the complex biological tasks for which they are responsible, the molecules within cells must contain a certain minimum number of atoms. Along the same lines, the proteins composed of these molecules must be a certain minimum size to hold up to their complex, varied jobs. Same goes for the lipids and carbohydrates, not to mention the highly complex cell organelles themselves. If, for example, a protein must perform 200 little separate tasks, then it needs to have, say 200 amino acids, each of which has 10 or so atoms -- my numbers may be way off (I'm sure!), but the point stands. Cells have so much they need to do! It's just way too much to accomplish using any fewer of the building blocks, atoms, in any fewer assemblies.

I believe nature tends towards the most efficient (hence, bubbles are round to maximize volume for a given surface area). Though cell functioning may seem unbelievably complex, it is really as simple as is materially possible, considering what the cell must accomplish!

Okay, enough for now!


Name:  Nomi
Username:  nkaim@brynmawr.edu
Subject:  
Date:  2003-11-16 19:42:53
Message Id:  7273
Comments:
Thanks to Brittany and Su-Lyn for clarifying some issues for me ... I agree. I must say I was really "mid-thought" when I wrote that last forum. To tell you the truth, it's actually quite a relief to find that I'm wrong (at least in some sense). I had myself scared there for a minute! -- trying to concvince myself -- almost fatalistic.

I thought Nancy had a very good point. She raises a difficult balance that people must strike between ACCEPTING something and becoming RECONCILED to it. We need, of course, to accept homosexuality and obesity, as well as any other characteristics, and to stop judging them. Judging does nothing. It's never a matter of "fault!" I think people are correct in looking for "the gene" behind these characteristics if they do so in an attempt to erase the concept of fault. On the other hand, fault should not exist in the first place, and there is really no need to "explain" or "justify" what simply IS.

...That is not to say there is a huge, essential difference between being homosexual and being obese. There is! Homosexuality doesn't hurt anybody (unless involved with some sort of abusive relationship, but that can happen anywhere). As such, homosexuality is not what we term "pathological" -- that it, it exists in the normal range, and we don't have to do anything about it! Obesity, on the other hand, is very dangerous, and so is pathological and SHOULD be changed, if possible. We should not become reconciled to being fat just because we might be able to explain it genetically! What I really want to say is, it's hard to strike this mental balance, to fight both ends of the blame-vs.-change battle. On the one hand, we don't want people to blame homosexuals, or the obese, for their conditions. On the other hand, we want the obsese to try to lose weight -- and to have them understand that their condition, unlike homosexuality, is physically dangerous. I believe it is a matter of erasing what is "morally objectionable" -- a useless social judgement to make, really -- and focusing on what is "personally or socially harmful." (So there go religious ideals -- out the window!)

I also want, before class tomorrow, to give my answer to the question about why cells have lower-limits for size. I think that, just as with upper limits, it is a practical, spatial reason. In this case, however, I think it has to do not with surface area but with molecular complexity. The smallest atom must still take up a certain amount of space. In order to perform the complex biological tasks for which they are responsible, the molecules within cells must contain a certain minimum number of atoms. Along the same lines, the proteins composed of these molecules must be a certain minimum size to hold up to their complex, varied jobs. Same goes for the lipids and carbohydrates, not to mention the highly complex cell organelles themselves. If, for example, a protein must perform 200 little separate tasks, then it needs to have, say 200 amino acids, each of which has 10 or so atoms -- my numbers may be way off (I'm sure!), but the point stands. Cells have so much they need to do! It's just way too much to accomplish using any fewer of the building blocks, atoms, in any fewer assemblies.

I believe nature tends towards the most efficient (hence, bubbles are round to maximize volume for a given surface area). Though cell functioning may seem unbelievably complex, it is really as simple as is materially possible, considering what the cell must accomplish!

Okay, enough for now!


Name:  Nomi
Username:  Anonymous
Subject:  
Date:  2003-11-16 19:44:31
Message Id:  7274
Comments:
SORRY I POSTED IT TWICE! ONCE WAS LONG ENOUGH ALREADY!

SO WHO'S THE STUPID ONE, ME OR THE COMPUTER?

Wait, don't answer that ... !

;) Nomi


Name:  adina
Username:  ahalpern@brynmawr.edu
Subject:  
Date:  2003-11-16 20:54:40
Message Id:  7276
Comments:
I agree with Nancy that, "if we find a gene for an unhealthy condition such as obesity, people will feel as if they shouldn't work to prevent it since it is genetically predispositioned," but I also think that if we do find a major contributing factor to obesity, it will be easier to treat severe cases of it medically.
Name:  MH
Subject:  
Date:  2003-11-16 21:59:53
Message Id:  7278
Comments:
"it leads me to wondering about genetic expression in other traits, and how we, as a society, seem to be moving towards a scientific explanations for things we don't tolerate well..."
--Nancy

This concept of genetic "predisposition" has been plaguing my thoughts recently. First, in response to Nancy, it leads me to wonder if these "explanations" presented to society are simply nothing more than an "myth" for our own understanding. This might be somewhat odd, but following the reasoning that for generations culture have used "creation myths" and other myths of sorts to explain the "unexplainable", it leads me to wonder this might just be a way to pacificy society with a short-term, easily accessible reasoning.

Is it possible to chalk up all that which we do not understand or tolerate as simply "the way it is"?

The explanation for predispositions is often sorted into one of two schools-- environment or genetic. Which is valid? Could it be that genetic issues are simply heredity and other the result of environmental factors? Here the example of identical twins seperated at birth becomes an interesting issue. While environment is often viewed as a formative force in the development of a child's personality and traits, many examples of identical twins, raised in opposite environments, show that despite differences in childhood and lifestyle, certain characteristics and preferences are identical. This, in its simplicity, is an example of the primordial argument of nature vs. nurture. It leaves me wondering if identity is really environmental or genetic.

[to see more about example of seperate identical twins go to following link: http://www.cbsnews.com/stories/2003/11/04/48hours/main581771.shtml]


Name:  Manuela C.
Username:  mceballo
Subject:  
Date:  2003-11-17 02:42:33
Message Id:  7283
Comments:
I think another factor that may come to play in the nature vs. nurture debate is will, personality, soul, whatever you may want to call it. It is a little frightening to think that who you are and what you are depends on things that you cannot control... like your genes or your environment, and that between one or the other, there lies nothing that leaves room for something our society values so highly: individual expression. Are we not responsible for our own actions because we are responding to biological predispositions or because we cannot help but reflect our upbringing? How does this affect the debate?
I don't know... just some random thoughts :)
Name:  Natalya Krimgold
Username:  nkrimgol@brynmawr.edu
Subject:  Genes
Date:  2003-11-17 09:53:28
Message Id:  7285
Comments:
The roles that genes and human will play in human attributes and behavior is a controversial and emotional issue. None of us would like to believe that all of our attributes and abilities are predetermined in the womb because we are aware of our failings and we would like to believe that we can improve upon them over time. It is obvious that our lives and environment and experience have so effect on our genes otherwise identical twins would behave in exactly the same way and really look completely identical. At the same time we sort of have to face up to the fact that our genes do determine, to a large extent, who we are, and we are limited by them.


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