View source for Telomere and aging

<p><strong><em><span style="font-family:times new roman,times,serif"><span style="font-size:24px">[Telomere &amp; Aging]</span></span></em></strong></p>

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<p><span style="font-size:16px"><span style="font-family:times new roman,times,serif"><strong><u>Definition</u></strong></span></span></p>

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	<li><span style="font-size:16px"><span style="font-family:times new roman,times,serif">Telomere: A repetitive sequences (TTAGGG, about 2500 time) length at the end of each chromosome, which protects the loss of DNA during cell cycle. It also involved in ageing measured by its reduced length.</span></span></li>
	<li><span style="font-size:16px"><span style="font-family:times new roman,times,serif">Ageing: In a word, it is a procedure of older. But in biological view, the definition is not precisely defined. Because there are no certain criteria of biological ageing, which can be shown as a fixed number (except our age calculated with birth) and each organism has each unique lifetime, it is very hard to determine.</span></span></li>
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<p><span style="font-size:16px"><span style="font-family:times new roman,times,serif"><strong><u>Criteria for Ageing</u></strong></span></span></p>

<p><span style="font-size:16px"><span style="font-family:times new roman,times,serif">Recently, the telomeres are suggested as the molecule that can determine an organism&rsquo;s age. By making standard telomere length in one species using blood or epithelial samples which are the most common samples, the age of target organism can be determined.</span></span></p>

<p><span style="font-size:16px"><span style="font-family:times new roman,times,serif">But still there is a drawback whether the standard sample is really standard for determining ageing. The telomere length in one organism is far varied for each organ within it, and the degradation rate is also varied. Thus many scientists are trying to create well-defined standard of telomere. The one way of determining the proper telomere length with standard is using RT-PCR. Firstly, make a sequence of size-defined primer set and other primer which binds to the upstream of telomere region. Then add two types of primers at once in PCR process, and compare the size of each product. In this method, the defined primer set should detect only one copy of DNA motif in the strand otherwise it can&rsquo;t be a standard.</span></span></p>

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<p><span style="font-size:16px"><span style="font-family:times new roman,times,serif"><strong><u>Reference</u></strong></span></span></p>

<p><span style="font-size:16px"><span style="font-family:times new roman,times,serif">1. <a href="https://en.wikipedia.org/wiki/Telomere">https://en.wikipedia.org/wiki/Telomere</a></span></span></p>

<p><span style="font-size:16px"><span style="font-family:times new roman,times,serif">2. <a href="http://hyper.ahajournals.org/content/37/2/381.full">http://hyper.ahajournals.org/content/37/2/381.full</a></span></span></p>