DNA and RNA
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30-03-2012, 07:06 PM
DNA and RNA
As I understand it, DNA has four bases: Thymine, Guanine, Cytosine and Adenine. Each base has its own partner, Adenine binds with Thymine and Cytosine binds with Guanine...right so far?

Now RNA has four bases as well except instead of Thymine it has Uracil. What puzzles me is that I though Uracil was a "mutation" of sorts of Thymine which can still bind with Adenine..right?

So does RNA have the same bases as DNA or can it have all five if we are to include Uracil as a base OR is Uracil merely an "alternative" so to speak to Thymine?

I am new to this molecular biology so if I sound like a total twat, then that is why. Tongue

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30-03-2012, 07:39 PM
RE: DNA and RNA
(30-03-2012 07:06 PM)Dragon-Wolf Wrote:  As I understand it, DNA has four bases: Thymine, Guanine, Cytosine and Adenine. Each base has its own partner, Adenine binds with Thymine and Cytosine binds with Guanine...right so far?

Now RNA has four bases as well except instead of Thymine it has Uracil. What puzzles me is that I though Uracil was a "mutation" of sorts of Thymine which can still bind with Adenine..right?

So does RNA have the same bases as DNA or can it have all five if we are to include Uracil as a base OR is Uracil merely an "alternative" so to speak to Thymine?

I am new to this molecular biology so if I sound like a total twat, then that is why. Tongue
I am in school for nursing, only in my first semester. We didn't go to in depth because my teacher is all about god did it bullshit. I do remember something similar to this from the past. I got this from Wikipedia.

In DNA, the evolutionary substitution of uracil for thymine may have increased DNA stability and improved the efficiency of DNA replication.

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30-03-2012, 08:02 PM
RE: DNA and RNA
In addition to the nucleobase uracil instead of thymine, RNA also substitutes the sugar ribose for the deoxyribise found in DNA.

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30-03-2012, 09:52 PM
RE: DNA and RNA
Didn't RNA actually come first? So technically Thymine would be the more stable substitute for Uracil. By the way the entire process of DNA-RNA transfer is probably vestigial (this is based on the fact that Virus's are just RNA, with no DNA, the reason they kept it is because it is advantageous for them to mutate rapidly, in more complex organisms this is a bad thing).
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30-03-2012, 10:10 PM
RE: DNA and RNA
The RNA World Hypothesis proposes that RNA came before DNA. It is however just a hypothesis and we don't know that is the way it happened.

Another hypothesis is that virus devolved from organisms containing DNA not vice versa.

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31-03-2012, 10:48 AM
RE: DNA and RNA
(30-03-2012 09:52 PM)TheKetola Wrote:  Didn't RNA actually come first? So technically Thymine would be the more stable substitute for Uracil. By the way the entire process of DNA-RNA transfer is probably vestigial (this is based on the fact that Virus's are just RNA, with no DNA, the reason they kept it is because it is advantageous for them to mutate rapidly, in more complex organisms this is a bad thing).
Yeah, this is what I have read. RNA is like the instructions or guide while the DNA is just the blueprints, so to speak.

See..some sources say that Uracil is simply a different nucleotide altogether while others say it is a variation of Thymine which can still bind with Adenine while others claim Uracil is a mutation of Thymine but its nature is such that the DNA polymerase has a difficult time differentiating it from Thymine.

What puzzles me is whether RNA always stays as RNA or can it sometimes fuse with other nucleotides to become DNA?

Anyways, its not like I am planning to pursue molecular biology; it is a passing, superficial curiosity but what I have read so far does give me better insight into some of the basics of DNA itself. Something I do not recall hearing anything about in high school science.

Thanks for the cool replies so far.

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31-03-2012, 02:28 PM
RE: DNA and RNA
There are more differences between DNA and RNA, You are right in that thymine is replaced with uracil in RNA, RNA is also single stranded, contains a ribose sugar instead of Deoxyribose(as found in DNA) it also contains one more oxygen atom than Dna.

RNA is also a far older molecule than DNA so if anything the addition of thymine could be seen as the mutation not the other way round.

As far as i know the reason RNA has a uracil instead of thymine, is to prevent it being misinterpreted as DNA which would be disastrous for a cell.

But at some point two RNA strands may have joined together giving rise to DNA.

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31-03-2012, 06:21 PM
RE: DNA and RNA
Ah...I see. Uracil differs slightly to avoid being seen as a mutation. The book I checked out said it was (or could be) a mutation.
Yet RNA has different forms and some, as I recall, are used to transport proteins or something so iti snot all cut-and-dry like it would seem.

Well..the book I had DID mention that there is much we still do not understand regarding DNA and RNA so much of what we are told is really just a hypothesis in works.

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01-04-2012, 06:52 AM
RE: DNA and RNA
(31-03-2012 06:21 PM)Dragon-Wolf Wrote:  Ah...I see. Uracil differs slightly to avoid being seen as a mutation. The book I checked out said it was (or could be) a mutation.
Yet RNA has different forms and some, as I recall, are used to transport proteins or something so iti snot all cut-and-dry like it would seem.

Well..the book I had DID mention that there is much we still do not understand regarding DNA and RNA so much of what we are told is really just a hypothesis in works.
This is the second time I've tried to reply to this thread, i typed a big reply and i lost my connection Censored

I'm basing that off of what a biology teacher told me along time ago, so i don't know exactly how accurate it is. Its entirely possible to just be theory.
If RNA was confused as DNA it would cause problems for a cell, So the differences between DNA and RNA must be enough for something in the nucleus to differentiate between them to prevent mix ups.

To show the point, some of the genetic diseases people suffer from today are caused buy our ancestors being infected by a retrovirus (a virus containing RNA instead of DNA) meaning our DNA still contains some of the coding for these viruses.
cracked had an article about it a while back.

So imagine how harmful it would be if our cells own DNA and RNA got mixed up.

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01-04-2012, 07:47 AM
RE: DNA and RNA
From what I gather, RNA is supposed to be more malleable than DNA which allows it to literally "shape" itself however it sees fit.

I am wondering if RNA is somehow used to repair damage to DNA or at some point was functional in a type of healing process that we no longer have.
But then again RNA seems to be a sort of "instruction manual" for the blueprint which is the DNA.
However RNA for viruses would have to be different yet again, I would think, since its primary function would be to somehow alter the contagion so that it can bypass the immune systems primary defenses or something whereas the RNA in our bodies appear to function as repair systems. Maybe?

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