Talk:Telomere

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[edit] Telomeric interval?

What is a telomeric interval? Tmangray 23:46, 11 April 2007 (UTC)

[edit] 5 to 3

what does "5' to 3'" mean?

It's how one describes the "direction" of a sequence of DNA bases. The 5 and 3 refer to specific atoms that are part of the deoxyribose sugar ring in the DNA's backbone; the phosphate links between two deoxyriboses connects the 5' carbon of one deoxyribose to the 3' carbon of the next one. I'd need to draw a diagram to explain it really clearly, but this is something that should be handled within the DNA article. Bryan Derksen

Here is a schematic:

3'-------------------------5'
<enzyme> -->
5'-------------------------3'

The enzyme works here from the 3' to the 5' end (each - represents a base pair). It moves along the 3'-5' direction polymerizing in the 5'-3' direction. All the polymerases that have been discovered polymerize in the 5'-3' direction. This is a very important point to remember if you want to develop a deeper knowledge of biology and the process of DNA replication (and RNA synthesis, because it follows the same rule except that the RNA transcript is made in the 5'-3' direction). Ashermadan

I already put the explanation in DNA. Did I get the direction right? phma

I remember reading speculations that telomere could cause problems with cloning since the DNA used would have already shorter telomere. I'm loathe to add that without having any source to cite, though.

Regarding telomere shortening as a time-delay fuse, the article currently states "These theories remain relatively controversial at this time.". Is that true? Could a reference be added to a paper arguing otherwise, or is it simply that the theory is very new and relatively untested? I'd love to here more detail about why it is controversial, others probably would too. Bmord 07:03, 7 January 2006 (UTC)

The article states that for most multicellular eukaryotes, telomerase is only active in germ cells. However, the reserve capacity hypothesis article linked in the references section asserts that some amount of telomerase exists in adult skin cells. Also, prior to 5 months of age, somatic cells in zygotes apparently also express telomerase. Could this be rephrased to something more correct? Thanks. Bmord 07:03, 7 January 2006 (UTC)

[edit] Heat Resistance +

"A side effect of the longer telomeres was an increased resistance to the effects of heat exposure. The reasons for that effect are unclear."

With the increase in global warming is this not an experimental aspect to explore on humans in Africa who die every day of heat related symptoms, as well as children left unattended during the summer that either die or experience life crippling afflictions? Depending on the true uses of such a new treatment, it would certainly be worth it to explore every possibility such a treatment would bring forth, would it not?

Reformatted --Chris 00:40, 8 July 2006 (UTC)

[edit] Misspelling on telemere page

The species Candida guilliermondii is spelled wrong, as guillermondii. This is especially a problem because elsewhere in Wikipedia Candida guilliermondii is classified under Pichia guilliermondii, which is an old usage, I believe. Makes it hard to look stuff up. It's not anywhere in the text, it's in the table of sequences. Richard8081 05:36, 17 July 2007 (UTC)

[edit] RNA in telomeres!

Here's a fascinating article: New Telomere Discovery Could Help Explain Why Cancer Cells Never Stop Dividing. Someone should really read the original article and include some of that information here. Unfortunately, I'm a bit swamped at work. --Slashme 08:11, 8 October 2007 (UTC)


[edit] Running Out?

How many years can the telomers shorten until their completly gone? —Preceding unsigned comment added by 70.100.23.242 (talk) 00:21, 19 January 2008 (UTC)

[edit] Tips of shoelaces

I first saw the metaphor of telomers as being like the tips of shoelaces in Science News.

Metaphors are common and useful in explaining science, in classes, magazines and textbooks.

I think the metaphor makes the function of telomeres easier to understand. I'm not sure what it takes away from the article -- perhaps people want the article to be serious and it's too mundane.

Can you tell me, SierraSciSPA, why you don't think it belongs in the article? I'm not insisting that it go in, but I just want to articulate a good reason, for the record. Nbauman (talk) 03:06, 30 January 2008 (UTC)

Well, for the record, I think the metaphor of telomeres to aglets is very questionable. Aglets have two main purposes: 1) to protect laces from fraying; and 2) to make laces easier to fit into holes. Telomeres have several known purposes, including: 1) to protect the ends of chromosomes; 2) to provide a disposable buffer for DNA polymerase, which cannot replicate a complete sequence of DNA; 3) arguably, to ensure that deletorious mutations will be only as long-lived as the Hayflick Limit and thus to reduce the incidence of cancer. Bottom line: while aglets and telomeres do certainly have one thing in common, it seems that the differences between them are far more significant than the similarities. I think drawing the comparison is more likely to mislead than to inform. I'm certainly not going to edit war over this point, but that's pretty much what I think of it.
That said, though, in general, I applaud your efforts to make this article more readable to a layperson. I myself *am* a layperson, and when I read it for the first time, I was completely bewildered. The article includes the sentence "during replication, DNA polymerase can only synthesize DNA in a 5' to 3' direction and can only do so by adding polynucleotides to an RNA primer that has already been placed at various points along the length of the DNA." How is any non-biologist supposed to be able to read that?? --SierraSciSPA (talk) 05:42, 30 January 2008 (UTC)
You're saying that we shouldn't use the metaphor that telomeres are like the tips of shoelaces, because telomeres share only one quality with shoelaces, but have many other qualities that they don't share with shoelaces.
I don't quite follow that. Science writers and teachers often use metaphors to get their ideas across, and the comparison usually shares only one point of description. For example, people compare the DNA molecule to a ladder, but a ladder has all kinds of qualities that DNA doesn't have. You can climb on a ladder, but you can't climb on a DNA molecule. Ladders are made of wood or metal, but DNA molecules are not. People compare the DNA molecule to a blueprint, but there are lots of differences between a literal blueprint and DNA.
Scientists use metaphors all the time, to explain and even to develop their ideas. They describe molecules as "gatekeepers". They compare a part of the brain to a sea horse, or a telephone exchange. Günter Blobel famously described his address tags to Zip codes. The Nobel Prize speeches are full of such metaphors.
Metaphors are a basic part of thinking. You can't be too literal and reject them. As you may know, one the symptoms of severe mental illness, such as Alzhemier's disease, is an inability to understand metaphors[1]. I'm not suggesting this is a problem here.<g> Nbauman (talk) 14:53, 30 January 2008 (UTC)
I'm not going to take a stance against all metaphors - but the two things being compared in a metaphor should at least share a primary purpose. DNA and a blueprint both contain instructions for structures; mitochondria and power plants both generate energy that will be used elsewhere. But the primary purpose of aglets is to protect the ends of something, and with telomeres I think that's only a secondary purpose - the primary purpose of telomeres is to enable the DNA polymerase to do its job, thus making replication possible. I almost want to argue that a telomere is more like copy machine toner than an aglet - that is, you need it to make copies, and it eventually runs out. Note, however, that I really don't want to say "telomeres are like copy machine toner" in the article :) --SierraSciSPA (talk) 16:37, 30 January 2008 (UTC)

[edit] Relative brightness

Is the grey of the chromosomes and the bright white of the telomeres in the photo the result of emitted light, or stimulated (how?) emission, or variations in reflectance / transmission? bucksylBucksyl (talk) 17:22, 18 February 2008 (UTC)


[edit] Immortal butterfly

What you'll get if you will connect the ends of the X's? Eternity ;) Denis Tarasov (talk) 09:03, 2 June 2008 (UTC)