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Ryu

Molecular Biology question

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Posted (edited)

Ok..as I understand it..DNA is made from RNA..right?

So there are particular nucleotides making up the base of RNA..am I correct so far?

Well..I seen something about mRNA (Messenger RNA) and tRNA (Transfer RNA) and it looks like the nucleotides that make up the base of those RNA's are different than "regular" RNA.

Please note..I am not student not very scientific so right now I am trying to get a grip on the basics.

P.S...ALSO what about the amino acid (I think) called 'uracil'? Is that basically a wild card, so to speak that appears in the RNA base? Does it ever occur in the template strand?

Edited by Ryu

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Its been a while since my biochemistry and genetics classes.

DNA and RNA are different but similar molecules. DNA is deoxyribonucleic acid, and RNA is ribonucleic acid. DNA is doubled stranded and RNA is usually single stranded. Both use nucleotides, DNA uses guanine (G), adenine (A), thymine (T) and cytosine (C ), while RNA uses the same with the exception of uracil (U) replacing thymine. With both RNA and DNA, G will pair with C, while A will pair with T or U, depending if it is a DNA or RNA molecule. U is not a 'wildcard', just a different nucleotide and is essentially serves as T in RNA and only pairs with A.

Most organisms use DNA to encode their genetic information, some viruses use RNA only. With an eukaryotic organism, such as ourselves, the DNA typically remains in the nucleus of the cell, in prokaryotic like bacteria, it is often a long loop throughout the cell. DNA encodes the information, while RNA does the synthesis of proteins in conjunction with the ribosomes. mRNA carries the information from the DNA to the ribosomes where the synthesis is done, tRNA transports the amino acids to the ribosome and mRNA.

In short, DNA is a long double stranded molecule that encodes the genetic information of the organism. mRNA is basically a copy of a smaller portion of the DNA, which then attaches itself to the ribosomes, and the tRNA brings the amino acids to the ribosomes and mRNA, the amino acids form polypeptide chains and eventually proteins.

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Thank you Insanity for the explanation.

However I still would like to know if the nucleotides for mRNA and tRNA are different than RNA.

I ask because I seen some diagrams of the mRNA and tRNA it it seems that there are different nucleotides within each..unless I read it wrong.

Thanks again.

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There are the same nucleotides, I believe that tRNA only has a codon, a set of three, while mRNA may have many. tRNA then matches amino acids to the codons.

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Thank you Insanity for the explanation.

However I still would like to know if the nucleotides for mRNA and tRNA are different than RNA.

I ask because I seen some diagrams of the mRNA and tRNA it it seems that there are different nucleotides within each..unless I read it wrong.

Thanks again.

Genetics 101 post

tRNA has some unique modifications to some of it's nucleotides to aid in its function.

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Thanks for the link, Copasetic.

I shall try to slog through this with my reptile brain. (seriously, studying this stuff seems to remind me of just how dumb I really am :D )

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Thank you Insanity for the explanation.

However I still would like to know if the nucleotides for mRNA and tRNA are different than RNA.

I ask because I seen some diagrams of the mRNA and tRNA it it seems that there are different nucleotides within each..unless I read it wrong.

Thanks again.

All RNA has the same nucleotides, but RNA can make many shapes since it is single stranded. What you were probably seeing is the different shapes of mRNA and tRNA.

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Ah..I see.

Thanks.

Not to sound redundant but there must be some sort of difference between the mRNA and tRNA that determines them to be what they are, isn't there? Like shorter strands or something.

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A common element between mRNA and tRNA is what is called a codon, which is a sequence of 3 nucleotides. Each codon codes for one, sometimes more, amino acids.

mRNA has specific a 'cap' sequence at one end, and a 'poly-A tail' at the other end, as well as a 5' UTR and 3' UTR regions in addition to the actual coding region. The coding region also has 'start' and 'stop' codons. All this is how the ribosomes determine which end to start reading from and when to stop reading. It is basically a single short strand.

http://en.wikipedia.org/wiki/Mrna#Structure

tRNA is more a folded or looped strand that is much shorter in length than mRNA. tRNA has a region called the anticodon loop which corresponds to a specific codon sequence in the mRNA and an acceptor stem which carries the amino acid to the ribosome. The loop areas do contain some variations of the uracil nucleotide.

http://en.wikipedia.org/wiki/Trna#Structure

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....now my head hurts.

So much to wrap my head around.

I think what puzzled me on RNA (or at least the different types) is that the amino acids correspond to several "codons". It seems that certain 'arrangements' can be used to represent something else....

Oh man! Molecular Biology is a complicated subject, isn't it?

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It can be. I had to had many structures and names and bonding memorized at one point. As well as certain synthesis processes.

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