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Mar
23
comment How to read this DNA inversion diagram?
That’s what I thought as well at first but if you actually look at the sequence of the red (flipped) bit, you’ll notice that it differs between the middle and the bottom picture: the red bit reads 5′→3′ TGCCGTCAG in the middle picture, but TGGGGTGAG in the bottom picture.
Nov
17
comment Giving life to a dead person
“all chemical reactions are irreversible in our human body” — what do you mean by that?! The opposite is true: virtually all chemical reactions are reversible, at least in principle (and many organic chemical reactions are practically reversible and, depending on the equilibrium, do in fact change direction). From the article you’ve linked it seems that you’ve simply misunderstood how the term is applied there: what they call “irreversible” reactions simply don’t occur spontaneous. Many cellular reactions are of this kind, i.e. they require energy and/or catalysts).
Nov
17
comment Alternatives to PCR
I think you misunderstood the question: it wasn’t asking whether a helicase could substitute a polymerase in the PCR, but whether it could substitute the heat cycling.
Nov
17
comment How do we know that humans and chimpanzees evolved from a common ape ancestor?
I don’t believe in deleting comments but the ones by J. C. Leitão and Cort Ammon, and the fact that they are so prolifically upvoted, reflects poorly on the community: They parrot an extremely naïve understanding of Popperian theory of science. People, please, don’t become so reflexively defensive of science that you put the meaning of words on their head. Of course science can prove things, and we can say that things are true. This isn’t “being careless” with words, but rather using words exactly the way everybody understands them. To say that “‘evolution is true’ is a faux pas” is inane.
Sep
23
comment Hydra immortality
@Dexter No, hydra is specifically investigated for its (presumed) lack of senescence, not just its regenerative abilities — unlike, say, planaria.
Sep
23
comment Senescence in space
Why would you suspect this? There’s not really any good reason to think so.
Sep
23
comment Why cancer is not a communicable disease?
@AMR You are still begging the question. You are saying, in essence, “cancer is not an infectious agent because it is not an infectious agent” — Not quite, but it’s simply not an answer. The question is why. You are systematically evading this.
Sep
23
comment Why cancer is not a communicable disease?
@AMR Immune response is the reason why they’re not communicable. That’s my point. All of the cases you’ve just listed actually contradict your survivability point, since they all rely on transmission in which cancer cells wouldn’t need to stay alive outside the body. Incidentally, I hereby acknowledge that there may be other reasons besides immune response. But I don’t know of them, and they certainly haven’t been mentioned yet here.
Sep
23
comment Why cancer is not a communicable disease?
@AMR I couldn’t find times of survival of individual (cancer) cells outside of medium. But plenty of bacteria and viruses die almost immediately outside of their host, and are still communicable by touch (prominent example: ebolavirus). I believe bacteria are generally more resilient but many are also quite particular about their growth medium and will just up and die when left alone. In other words: I think you vastly overstate the difference in survival between cancer cells and viral and bacterial pathogens. I don’t think this specifically is what distinguishes them: Immune response is.
Sep
23
comment Why cancer is not a communicable disease?
@AMR Put differently, since there are tumours that are communicable (no matter how few), we must ask ourselves: “what makes cancer non-communicable in general?” The other reply, which just says that “cancer is not a pathogen” isn’t answering the question, it’s begging the question. By contrast, my answer actually explores the specific difference between pathogens and tumours. This is fundamentally different from claiming that they are the same.
Sep
23
comment Why cancer is not a communicable disease?
@AMR No, I do not “want to classify cancer as a communicable disease”. I’m explaining why it isn’t communicable by considering what distinguishes it from other diseases (which are communicable). Explaining differences this way is a common teaching technique which apparently backfired here. But I’m not really sure how to improve that—maybe put the third paragraph in bold? Incidentally, the misunderstanding seems to be related to your use of the word “compare” as if it meant “claim that they are equivalent” when, in reality, “compare” just as well may mean “contrast”. That’s what I’m doing
Sep
22
comment Why cancer is not a communicable disease?
@AMR Please explain why you find the comparison spurious — I don't understand that at all. It's also patently contradicted by the existence of communicable cancers. And the lack of survival outside the host is in no way relevant for the comparison I'm making. At any rate, many pathogens (both bacterial and viral) have the same problem.
Mar
23
comment Genes-of-interest analysis between organisms
@AliceD RNA-seq is a gene expression profiling technique akin to microarrays. The sequencing step is just a technical detail.
Feb
7
comment Why cancer is not a communicable disease?
@Kendall I have to admit that I don’t know anything about that, but please feel free to add your own answer and/or edit mine. Also, thanks for this interesting piece information, I didn’t know that.
Feb
7
comment Why cancer is not a communicable disease?
@GoodGravy No, it’s not a moot point at all, because it doesn’t explain why cancers generally aren’t transmissible, and that was the whole question. (I also disagree with your edit, since it changed the answer substantially, and such edits are frowned upon on Stack Exchange – you should have written your own answer instead.)
Feb
7
comment How do I find a protein from this DNA sequence?
Translation would fail on this sequence since it’s not a complete open reading frame (doesn’t start with a start codon, doesn’t stop with a stop codon, and length not divisible by three). As such, we don’t even know whether it’s in frame, or maybe shifted by a nucleotide.
Feb
7
comment Why cancer is not a communicable disease?
I’m unhappy with this answer, and although I haven’t downvoted it, let me try explaining why it was downvoted. First of all, as you note yourself later on, your initial sentence is simply wrong: many cancers are caused by infectious agents. More importantly though, your premise is fundamentally flawed: again, as you show yourself, cancer itself is an infectious agent (ever heard of metastases?). So why, then, is it usually not transmissible between individuals? Your answer doesn’t explain that at all.
Jan
21
comment What were the first neural systems like?
@ChrisStronks We know tons about evolution that isn't preserved at all in the fossil record. For instance, we can study evolutionary model organisms and do comparative genomics. In fact, fossils play a fairly minor role in the modern study of evolution.
Jul
2
comment Did animals evolve from plants?
@KeithThompson Indeed, it does have these implications: There are potential hard-to-cross thresholds to higher life forms, which prevents their abundance in the Universe (and may help explain the Fermi paradox), but evolution of multicellularity is not one of them.
Jul
2
comment Did animals evolve from plants?
@Keith Ha! Actually, “Multicellularity has evolved independently at least 46 times …