Paralith

I agree with INow. As far as I know, potassium and sodium use the same gate molecule in neurons.

It started Tuesday or Wednesday... in August.

ah.

my vote's for a cankersore. They take the form of bumps with the white depression in the middle. I'm afflicted with those every now and then - and they do sometimes start where you've scraped or cut the skin on the inside of your mouth. Supposedly drinking a lot of acidic drinks like coffee or tea can also cause them, and they tend to happen more often if you're stressed out (stress often compromises the immune system). It's like a little bacterial infection, and using a strong mouthwash or over-the-counter mouth antiseptic will help it go away much quicker. And I've had particularly nasty ones that last for over a week. If it started on Tuesday or Wednesday I'd say it's probably getting to it's worst stages about now. And yea, they can get pretty painful. I would recommend eating mild foods for the next couple of days - nothing too salty or acidic. Cuz it'll hurt like hell.

This was already discussed in another thread.

http://www.scienceforums.net/forum/showthread.php?t=28871

To paralith

 

You are correct in that shortened telomeres reduce cell division - hence cancer. Where that argument breaks down is that a cancer cell undergoes a kind of cellullar regeneration, meaning all telomere bets are off! The fact is that older people suffer much more cancer than younger, meaning that telomere length as a factor is much outweighed by other factors, such as more cellular mutations, and reduced immune response. Thus age causes cancer, not preventing it.

That's what I'm saying, man. AGE does NOT prevent cancer. The shortening of telomeres does. For the sake of the argument, it doesn't matter that older people have more cancer than younger people. What matters is that by having telomerase not function in normal somatic cells, and by having other cancer-preventing genes functioning correctly, there is a greater chance that cancer can be held off until the organism has had a chance to successfully reproduce. As we all agree, as time goes on and mutations have a chance to occur, obviously a mutation that activates telomerase and/or de-activates a cancer preventing gene will most likely cause cancer to form. But hopefully by that time reproduction will have already occurred, and since anything that happens now is something evolution will effectively be blind to, the fact that the cancer-prevention mechanism will now cause your body to break down will not be selected against. So in this sense, aging/the breakdown of your body is a side effect of a cancer preventing mechanism.

This is, of course, assuming that the shortening of telomeres is in fact a mechanism to prevent cancer. We don't know that for sure, but I think it is definitely a plausible hypothesis.

This argument between you two is going in circles. Let's try phrasing this argument somewhat differently. The (purported) mechanism that prevents cancer causes (or at least significantly contributes to) the eventual breakdown of the human body. It's not that aging stops cancer. It's the reduction of telomeres that stops cancer. And it's the reduction of telomeres that contributes to the breakdown of the body. This breakdown of the body increases as age increases, since telomeres decrease as age increases, and this breakdown in itself is often called aging, though technically aging should simply mean an increase in the amount of time you have been alive.

There. Does that help?

Edit now that I've seen INow's post: Again, let's rephrase. Every time your cells divide aka their DNA replicates, there is a chance that a mutation that could cause cancer will occur. Thus the higher the number of times your cells have divided, the higher the chance that a mutation that causes cancer has occurred. Since the number of times your cells have divided increases as your age increases, the chances that you have contracted cancer increases as your age increases.

Now, I'm not going to get into the argument about whether that's correlation or causation or both, but I think you all are arguing much more about the letter of the law than about the spirit of it.

It seems to me like you guys are drifting off into physcology mixed with your biology. Physically, the reason we age and eventually die is our telemers shortening until they are gone (then we die) and the fact that everytime our DNA is copied during mitosis it develops errors, (mutations). I've personally never heard of an entire species evolving to protect against one specific disease (cancer). And the fact is that teenage kids cannot raise kids in our new technological world. Thats a social problem, not a biological one. Cancer and the inability to raise kids is something we fear, and not our bodies, if that makes sense, so our bodies dont prepare for these things.

 

Something else is, in my OPINION, is that cancer is not a naturally occuring thing. it is the affect of human inventions that emit radiation and the toxic molecules we create and expose ourselves to, like old insulation, and high-energy producing waves.

Cancer is indeed naturally occuring, and it is more likely to happen the longer you live; aka, your cells have divided more and more allowing more and more chances for a mutation to occur. And since cancer can kill you and can most certainly impede your ability to both have children and successfully raise them, it makes sense the we may have evolved mechanisms to counteract oncogenesis.

Oh, those pesky females with thier seperate reproductive interests.

Well guys, next time you want to take the load off and bring the kid to term for us - oh wait, you can't. Only we can. =p

So how does this relate to the topic at hand as somatic cells can also undergo variation all through the body over a lifespan, in which case I don’t doubt some become cancerous, but how does a telomere then react to such a situation? Does the telomere actually do anything special at that point in time, and again how does it know.

There is an enzyme which rebuilds telomeres, called telomerase. However, in most normal cells, it is not expressed; the gene for telomerase is turned off. In cancer cells, the gene gets turned on. The gene is also turned on in embryonic stem cells and in other cell lines that need to divide very often, but other than that, most somatic cells do not express it.

wow - lots of responses!

I suppose I'm wrong and you're right!

 

However...

In answer to "wouldn't the same happen to women who masturbate?" - Women KNOW if they've reproduced properly because they'll get pregnant, however men don't notice any bodily changes after they masturbate OR reproduce, so they don't KNOW if they've reproduced or not (I don't mean in their CONSCIOUS mind).

It doesn't matter if you KNOW, consciously or unconsciously, that you've reproduced. What matters is if the genes that led to certain behaviors resulted in more children being born with those genes, then those genes will increase in frequency in the population as generations pass. So, if a male had genes that "told" him to die after a certain number of ejaculations, and if he also had genes that "told" him to masturbate a lot, then he would waste all his ejaculations on masturbation and he would leave no children, and his genes would cease to exist in the population. It simply wouldn't work, my friend.

That's theorized as a molecular reason. I think what Mark wants to know is if there's an evolutionary advantage behind living long after your reproductive years are over (and are no longer passing down your genes). It's a very different question.

 

Presumably, the fact that we live along time is favored by evolution, otherwise we would have never evolved the mechanisms to live so long. It's not really energetically favorable from a evolutionary perspective.

 

However, to assume this may be ignoring modern medicine and health care. And the effect is has on the phenotypic plasticity of living to old ages. It could be, humans really didn't live that long past reproductivity, but not because it's encoded in our genotype. If that particular phenotype was never expressed, it couldn't get selected against.

There is one theory that says humans evolved relatively longer lifespans for the purpose of multi-generational child care - in other words, grandma can still contribute to her reproductive success by helping take care of her grandchildren. And considering the relatively large amount of time and effort required to successfully rear a human child, probably any extra help the parents can get will make a difference. And I say relatively longer lifespans, because obviously today's medical advances have increased our lifespans considerably. Still, even before then, we did tend to live longer than most other mammals.

Since the selfish man was both conceited, self-centred, and pessimistic...

And there is the flaw in the story. A person who does not believe in a god is not necessarily conceited, self-centered, or pessimistic.

Religion can be a source of strength and comfort for people, but it can also be used as an excuse to persecute other people doing things you don't like. And I would think that people who feel they have the divine and moral right to continue this persecution would probably go to lengths and extremes they wouldn't otherwise go to.

I admit I don't know much about abiogenesis, but it seems to me that perhaps an extreme environment of the right kind could potentially increase the chance of life naturally originating. But I'll defer to people who know more about the specifics.

My lab looks a lot like ecoli's up there, with the addition of the mouse area. Our mice are in the barrier room, so we gotta get all dolled up in these space suit things here to keep the mice nice and clean and healthy:

And here are (or were, rather, before we dissected them) some of my mice, running on a testing device called a Rotarod. Basically, the mouse that falls off last has the strongest muscles.

you've terrible misquoted me here. someone said that i should take one person's account as universal truth. what i said in response is just because one person has a single account of life on a farm does not mean that it is true for all animals' lives on farms. i said "because there is one farm that doesn't mistreat their animals does not mean that there are no farms that do so." that's quite different.

I imagine that "someone" is probably me. If that's what I said, then I mispoke. What I meant is that you have a first person account of a farm where animals are treated well, and that this should be proof that food animals can and are, in some places at least, treated humanely. And clearly, you agree with me. No, this does not mean food animals are treated humanely on every farm, and I said as much myself earlier. This does, however, over turn your condemnation of all people who eat meat, since clearly those who eat meat from humane farms are adding enjoyment and nutrition to their lives without undue suffering of the animals involved.

really? sounds like a pretty good argument to me. but then maybe you don't mind being selfish.

however, i do not believe that the majority of animals raised for food are treated humanely. they suffer and then they die. i can only speak for myself, but i'd much rather live a free, natural life, even for a few months, than one in a cage or a pen.

it's the quality of the lives of the animals that i'm most concerned with, not just the killing of them.

I know Dr.DNA already went here, but yes, I don't mind being selfish about some things, and clearly you don't either. You buy yourself internet when you could spend your money and time on a more worthwhile cause. I'm sure you've had your fair share of birthday parties - why make your friends waste their money buying you material objects when they could spend that money on the poor as well? Let's be realistic. If you go down that road, this is where you end up. As humans we claim the right to do things that will make us happy, so long as we do not cause suffering to others in doing so. And since you won't even take the word of someone who worked on a farm that food animals are well treated, then I doubt anything other than a tour of the land's ranches will change your mind. Yes, there are ranches and farms that treat their animals poorly. But that is not very common in the US and other industrial nations, and is becoming less common across the world as well.

It doesn't seem to me that you are talking about the ego as in an individual's personal identity - it seems more like you're talking about egoism, as in thinking that which involves yourself more important than that which involves other people. Selfishness, in other words.

I wouldn't call that a necessary element of the human psyche, but a necessary element for a reproductively successful organism - yes. Whether conscious or not, behaviors which in the end best help yourself are those which get passed on the most. Most modern human cultures, however, frown upon selfishness, because a group of individuals cooperates and functions better when they are selfless towards each other - mostly in order to out compete a different group. Again, in the end, selfish.

I think that a certain degree of selfishness is inevitable in human nature, and we as humans have to learn to balance this instinct with our more logical and moral desires for a better society. How each individual chooses to do so will result in the broad spectrum of egoism that you covered in your many points.

um' date=' i guess if you want to eat roadkill, that's up to you. sounds pretty gross to me.

you can try to set up various hypothetical questions and situations and try to talk me into a corner, but i'll still say that eating meat causes suffering and we don't have to in order to survive and i wish that more people weren't so selfish. just leave animals alone and let them live their lives with as little human intervention as possible.

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It doesn't matter how many times you say it. If you don't back it up, it will have no validity. iNow did raise a valid point. So if your trying to convince all us meat eaters otherwise, appeals to emotion/pity and ad hominems will not help you.

 

I agree. If you're going to condemn something just because it's selfish - well, there are many, many things human beings do that are ultimately for selfish reasons, so that alone is not enough of a counter argument. Especially since, as SkepticLance pointed out nicely, human treatment of food animals can allow them to live a pretty decent life.

 

That really depends on what predator you are talking about. While the above may be true for cats for example, there are some predators that kill their prey instantly. The electric eel comes to mind here.

 

haha, speaking of relativity, how many human food animals would be hunted by electric eels in the wild? realistically speaking, the predators that would hunt cows and pigs and sheep are not likely to give them a quick death. In fact, some would begin to dig in before their prey is actually dead.

That's how that started. I was agreeing with creato that it takes faith to believe in evolution, by pointing out that most people who believe evolution is true do so because they believe the scientists who tell them so. The relevant biologists are the ones looking at the data, not most people. So it would be secondhand knowledge about a subject which people are highly biased about.

But I think the faith creato is talking about and the faith you're talking about are different. In the context of the average layperson, yes, they do have to take the word of a scientist who understands it. But creato doesn't just mean laypeople, he means everybody, even scientists. Even you said, a rational man can still doubt evolution. A rational layman (at least in regards to evolution), perhaps - but a rational man in possession and understanding of all the facts? No, that man could not. Unless he really really didn't want to believe evolution, even in the face of the data itself, and at that point, he's not really a rational man anymore.

Because it conflicts with Christianity, and Christianity is a highly political subject. Some people think that Christianity and evolution can be reconciled, but that cannot be done without fundamentally destroying one or the other.

A modified Christianity could survive with evolution. But a strict, literal version of Christianity could not, in that I agree with you.

That I agree with.

I'm very glad to hear it.

I am not saying the evidence isn't there, only that I do not have the time to personally verify it myself, nor do I trust anyone's opinion on this issue because of how politicized it is, be they a scientist or not.

I'm a little perplexed about what you're doing here, Mr. Skeptic. I can understand your view point as expressed above, since I'm kind of this way myself when it comes to global warming (don't jump down my throat, people) - but since I definitely don't have the time to become knowledgeable about such a politicized subject, I don't try to argue with people about it one way or another. But you are most certainly arguing, rather vehemently, with knowledge that you just confessed above that you don't have the time to verify. If you decide that you don't want to believe in evolution until you yourself have become an expert in it, then what are you arguing with us for? You're not an expert, our statements are apparently untrustworthy, so why even bother?

I think it's a pity, though, that you don't trust anyone here because evolution is so "politicized." I know I'm biased since I'm a biologist, but I see nothing political about the science of evolution at all. It only becomes political when creationists etc. try to twist science in order to justify force feeding children a religious message disguised as science. But when it comes to the scientific community, there is nothing political about it. It may not all be evidence you personally understand, but there is more than enough to convince people who are knowledgeable about the subject that evolution is indeed a real phenomenon.

Why just because i believe animals have the same right to live, as we do.

 

Thats actually a good quality which points towards that i am a caring and loving person. I feel sorry for your kids, and the kind of morals you will teach them.

 

I have no objection to eating animals, its natural. Its just the manner in which they do kill them which I object too. Like if they did it in a painless way that would be alright, but to have animals boiled alive is just plain nasty and uncalled for.

Boil alive? I'm pretty sure the only animals that get boiled alive are lobsters and crabs. And I think we can all agree that their level of consciousness is far below that of a pig's. Besides, it sounds awfully hard to boil a pig alive. They're big animals and they would kind of object to being thrown in a giant pot, you know? It's in the interest of the meat industry to kill their animals as quickly and stress-free as possible, because the stress hormones can cause the meat to taste badly. This was mentioned many times in a different thread.

At least some proteins are folded into different shapes than they normally would by means of chaperone proteins. So the amino acid sequence is not everything.

 

As far as I know, the protein's function is determined by its shape.

Well, in order to interact with that chaperone protein, both the interactee and the interacter have to have the right shape motifs in order to bind to each other - which is, again, determined by each individual protein's amino acid sequence. But you are right, many proteins don't reach their functional conformation without interaction with other helper molecules - anything from other proteins to inorganic ions. Hemoglobin, as mentioned by qwerty, is four subunit proteins surrounding an iron atom. These subunit proteins in turn have structures that bind to oxygen; and when one of the subunits binds to and O2 molecule, this changes it's conformation slightly, which then slightly changes the conformation of the other three subunits, making them even more likely top pick up O2 molecules themselves. It's definitely all about shape and structure.

No, not a teacher - not yet, anyways. I just don't like doing people's homework for them, so I thought that was the best way to get science45 to think about it him/herself.

Well, I'm not an expert in proteomics, but researchers have begun to identify certain amino acid sequences that form specific structures, or motifs, as they're usually called. One sequence might form a DNA binding site, for instance; and yes, some sequences are known to form structures that interact with other proteins. But there is still a LOT left to be learned.

If a mature spermatozoa, aka sperm, and a mature egg had 46 chromosomes each, when they fused into a complete human embryo, it would have 92 chromosomes. Does that sound right?

A spermatogonium is a stem cell that gives rise to sperm through meiosis. So, how many chromosomes would a cell have, if after meiosis, one of its daughter cells had as many chromosomes as a mature spermatozoa?