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Science questions not worth a thread I: I'm a moron!

Discussion in 'Science & Technology' started by The Imp, May 4, 2010.

  1. IdiotsOpposite

    IdiotsOpposite Boom, headshot.

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    It's not that they repair themselves, but rather that improper cell division is impaired in favor of proper cell division.

    Or so I think. :)
     
  2. Narz

    Narz keeping it real

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    But if the cells had already improperly divided wouldn't it follow that continuing to divide, even perfectly would still lead to imperfect cells?
     
  3. SS-18 ICBM

    SS-18 ICBM Oscillator

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    It depends on the ability of the cell itself or other cells to trigger either repair or apoptosis (cell suicide).
     
  4. GoodGame

    GoodGame Red, White, & Blue, baby!

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    There's a couple theories on the aging.

    One of the main one has to do with the ends of the DNA which don't get fully replicated due to an inherent problem. The problem is the lack of room on the template strand of DNA since the DNA replicating enzyme needs a bit of leading space on a template to bind and begin replication. That results in a bit of the end of the DNA being lost. The cells have a partial ad hoc solution based on an enzyme called telomerase which adds an end to the DNA, but the problem is that telomerase just writes any old end, so even if DNA space is not lost, the DNA info of the ends is still lost. The exact amount of DNA lost isn't enormous compared to the size of the genome, but in theory it adds up over someone's lifespan. Complicating the problem I believe, is that large numbers of coding genes are situated on the chromosome close to the ends that get lost (which accelerates the loss of important info).

    The other problem is damage/mutations to individual DNA bases. Basically even water can harm bases chemically as can a host of mechanisms. But so can free radicals, ionizing radiation, etc... The cell has many enzymes, mechanisms, etc.. to try to repair damage, but some of those mechanisms are non-specific so they can cause loss of DNA information even if the repair works. So this can cause aging, but also cancer.

    I'm not sure if there's more theories on aging. Possibly the human genome has in-built healthcare death squads???

    BUT YEAH, CELLS do try to repair themselves, unless the decision is made to just terminate a cell. The worst kind of damage is the type that can cause cancer by major chromosome rearrangements which is when both DNA strands of a chromosome simultaneously break. Repairing that also tends to lose information. IIRC, lots of that type of damage tends to trigger cell death.


    I'm not sure what IO meant by improper cell division, other than a really messed up situation in cell division would be to get the wrong number of chromosomes since that would effect the level of gene expression.

    A big problem is regulation of the cell cycle (WHEN to grow, when to divide) which is a major effect of the DNA damage that leads to cancer.
     
  5. Narz

    Narz keeping it real

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    Thanks GoodGame, with all that in mind how is anti-aging possible? I mean it clearly is possible but how?
     
  6. The_J

    The_J Say No 2 Net Validations Retired Moderator Supporter

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    Not with anti aging cream :D.
    I don't think that anti aging is possible in the way you think, but you can slow the aging down.

    Btw, that's why cancer research is interesting in that field. Cancer cells can reproduce themselves endlessly, so they somehow don't age in that sense.

    The system is error tolerant, you don't have to work perfectly to work at all (but yes, right there).
     
  7. Narz

    Narz keeping it real

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    Yo momma's so stubborn her cancer died of old age! :D
     
  8. peter grimes

    peter grimes ...

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    Is this true??
    How long has a particular strain / batch of cancer cells gone on reproducing?
     
  9. The_J

    The_J Say No 2 Net Validations Retired Moderator Supporter

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    :D

    No idea, humans are not in my working field :D :dunno:.
    But it's quite a bit longer than normal cells, and they are also a lot more resistant than normal cells.
    Normally, when you ask some lab scientist about animal/human cell cultures, he'll always say something like "Uh, attention, don't breath to strongly, they'll die", but cancer cells are even used at industrial levels, so they are not that sensible.
    I think you are dating cancer cell lines back in years, so the first cells from a currently used line might be maybe older than you.
     
  10. MrCynical

    MrCynical Deity

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    Yes, it's true. Usually cancer cells die with their host, so most strains actually don't last very long, but that isn't due to any fundamental limit in the cells themselves.

    HeLa cells are a good example of the immortality of cancer cells. The original HeLa cells came from a woman called Henrietta Lacks, who died back in 1951. The cancer cells are still going strong though, and are commonly used in research.
     
  11. Mise

    Mise isle of lucy

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    I've found this series very useful in working out financial thingies, such as mortgage interest rates, repayment schedules, NPVs, etc. Except not the infinite sum, that's less useful.
     
  12. admiral-bell

    admiral-bell Chronic Lurker

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    http://en.wikipedia.org/wiki/Canine_transmissible_venereal_tumor

    According to the almighty wiki, this one strain of cancer may be over 2,000 years old.
     
  13. GoodGame

    GoodGame Red, White, & Blue, baby!

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    I learned recently about microRNA having a regulatory role on which genes are actually expressed into protein, and how this might be important to disease states and other cellular changes, including the aging process. I guess you might add that to your list of theories about aging. Pretty neat stuff.

    Don't know if you can see this linky or not: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2705847/

    There's more in PLOS which should be free: http://www.plosone.org/article/info:doi/10.1371/journal.pone.0010724

    Pretty neat is this can pretty much apply to anything that we consider a sign of "healthy" at the cellular level, like mitochondria, electron transport system, etc..

    That'd make aging pretty complicated. It could because your genome is programmed to turn off certain genes, and that intertwines with aging being caused by oxidative damage, if say your body's ability to repair that damage were shut off at the genome level.
     
  14. emzie

    emzie wicked witch of the North

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    There's no reason that aging must happen. If a cell is damaged in such a manner, and it self-destructs (programmed cell death) there's no reason an undamaged cell can't replicate and fill that place. For some animals (hydras) this is true and they can live forever young.

    The thing is, replacing damaged cells takes energy, energy that might be better spent elsewhere, like reproduction. There's give-and-take between reproduction and maintenance. Obviously the body must be well enough maintained to reach reproductive age; on the other hand, diverting too many resources towards repair hinders reproductive efforts. A third factor comes into play at this point, environment. If an individual is at high risk of predation, disease, starvation, there's little reason to invest highly in repair to collect in on a longer breeding life. Another way of saying that is if on average, a rat dies within 2 years of birth, there's no reason to work hard keeping the body fit to live for 10.

    There's a lot of parsimony in this and it holds out pretty well among observed species. I think that's why we age, and the how is in gradual build up of defects like you listed.
     
  15. GoodGame

    GoodGame Red, White, & Blue, baby!

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    I'd agree there's no reason aging must happen, but only through intelligent intervention, in the same way there's no reason, other than gravity itself, that stuff must fall down.

    There is natural genomic regulation in place that prevents cells from replicating indefinitely, else we would have more lines of stems cells, and we wouldn't have aging except as a rare disease. The problem is that genomic regulation is not as simple as people hoped during the sequencing of the first genomes. There's lots of non-coding sequences in the DNA, some of which get transcribed and play roles in regulation, like microRNA (miRNA). Which is what I posted just above. Amazingly, I'd been learning about miRNA through the filter of Public University, but the role of the them in genomic regulation didn't enter my brain until very recently. I'd been taught they were just doing anti-viral duty, preventing viral DNA from integrating into the genome.
     
  16. Narz

    Narz keeping it real

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    I really want to believe that aging will be overcome in my lifetime (especially before I get really old [40+]) but it seems highly unlikely. Seems like the understanding & treatment of degenerative diseases nowadays is still in an extremely primitive stage.
     
  17. ParadigmShifter

    ParadigmShifter Random Nonsense Generator

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    Dude you are tripping.

    They're never gonna release any anti-aging that works unless it costs big $$$$.

    And I thought you liked the environment and stuff? Everyone living much longer is the worst case scenario for that.
     
  18. Narz

    Narz keeping it real

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    I didn't say I wanted everyone to stay young, just me. ;)
     
  19. PlutonianEmpire

    PlutonianEmpire Socially Awkward Goofball

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    What is the range of stellar spectral types that are affected by the giant flares observed in lower mass stars, and how long does it take for those stars to stop flaring?

    Spoiler :
    It was difficult for me to try to word this sentence in a manner that you would understand the question. :undecide:
     
  20. Perfection

    Perfection The Great Head.

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    Well, I don't think flare stars stop flaring until they actually die (which is longer than the current age of the universe). As to how small stars can be without flaring, I dunno!
     

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