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WHY RNA IS MORE REACTIVE?

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WHY RNA IS MORE REACTIVE?

Postby HELISA » Mon Mar 20, 2006 1:40 pm

Hi,
I found somewhere the conclusion that: it is thought that life arose as RNA, because it is more reactive. How come? Can somebody explain me why RNA is more reactive? What this molecule has inside its structure that is said to be more reactive than DNA? All the best!
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Postby Poison » Mon Mar 20, 2006 4:36 pm

DNA is double strand. Make bonds. But RNA is single strand.
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How about OH group?

Postby HELISA » Mon Mar 20, 2006 6:41 pm

Is this the only reason?
I found the information that RNA reactivity is somehow connected with its Hydroxyl group at 2' position, but how this group affect reactivity of RNA, I have no clue...
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Postby Poison » Tue Mar 21, 2006 7:18 pm

I don't know either. Maybe some other members can help us.
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Postby kiekyon » Sat Mar 25, 2006 4:20 am

perhaps it is because the dna is longer and more complex...
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Postby mmiaosmiling » Sat Mar 25, 2006 6:49 am

RNA is single strand and it has 2 -OH(hydroxy) in 2' position and 3' position but DNA has only 1 in 3'
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Postby dae » Sun Mar 26, 2006 5:09 am

Take this question logically. As mmiaosmiling points out, the only difference between DNA and RNA, as the name implies, is the 2' hydroxyl group. This hydroxyl group makes RNA less stable than DNA because it is more prone to hydrolysis.
To expand on that, consider that in a DNA backbone, there are no free hydroxyl groups (the 3' and 5' hydroxyl groups link the 2-deoxyriboses together via a phosphodiester bond and the the 1' has been removed to attach the sugar to the nucleoside). In a RNA chain, each ribose has a free 2' hydroxyl group that is a nucleophilic center.
The consequence of this on stability is drastic, the oxygen can attack both intramolecularly (as exemplified in splicing) or intermolecularly (which may be part of the reason that it is difficult to form dsRNA longer than x00 n.t.)

In response to the initially proposed question, I have heard that some RNA can self-reporduce, which is a very interesting phenomenon when one is addressing the origin of life. It may be worth inquiring into.
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Postby kiekyon » Sun Mar 26, 2006 9:01 am

from wikipedia,

Unlike DNA, RNA is almost always a single-stranded molecule and has a much shorter chain of nucleotides. RNA contains ribose, rather than the deoxyribose found in DNA (there is a hydroxyl group attached to the pentose ring in the 2' position whereas DNA has a hydrogen atom rather than a hydroxyl group). This hydroxyl group makes RNA less stable than DNA because it is more prone to hydrolysis. Several types of RNA (tRNA, rRNA) contain a great deal of secondary structure, which help promote stability.
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Postby kiekyon » Mon Mar 27, 2006 8:41 am

dae wrote:
In response to the initially proposed question, I have heard that some RNA can self-reporduce, which is a very interesting phenomenon when one is addressing the origin of life. It may be worth inquiring into.


how so??
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Postby angel » Mon Mar 27, 2006 9:36 am

kiekyon wrote:
dae wrote:
In response to the initially proposed question, I have heard that some RNA can self-reporduce, which is a very interesting phenomenon when one is addressing the origin of life. It may be worth inquiring into.


how so??


RNA has a replicase activity, that was found in some lower organism. Also, it has got self splicing ability. it can give rise to DNA using reverse transcriptase and also the polymorphic forms of RNA that are required for protein synthesis. These abilities make it a powerful molecule. it may be very much possible that it gave rise to life.
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Postby kiekyon » Tue Mar 28, 2006 2:08 am

angel wrote:RNA has a replicase activity, that was found in some lower organism. Also, it has got self splicing ability. it can give rise to DNA using reverse transcriptase and also the polymorphic forms of RNA that are required for protein synthesis. These abilities make it a powerful molecule. it may be very much possible that it gave rise to life.

so, first we have RNA based organism, then evolved to DNA??
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