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A DNA template having the base sequence -U-C-U-A-C-U- what is the mRNA base sequence?I...
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This question is incorrect. There is no uracil in deoxyribonucleic acid. The nitrogenous bases in DNA are A, T, C, and G. Maybe the sequence you have is the actual messenger RNA sequence UCUACU. Therefore, working backwards, the DNA complementary strand would be A-G-A-T-G-A. The base pairing rules when messenger RNA copies the DNA template is as follows. If there is the base A (adenine) in the DNA, it pairs with U (uracil) in the messenger RNA. If there is a T(thymine) in the DNA, it pairs with adenine in the mRNA. If there is a C(cytosine)in the DNA, it pairs with guanine in the mRNA. Finally, if there is a G(guanine) in the DNA, it pairs with cytosine in the mRNA.
Posted by trophyhunter1 on April 29, 2012 at 11:37 PM (Answer #1)
Let's back up a bit... DNA codes for RNA which codes for proteins. Without proteins, life cannot exist. DNA is a series of A T C G A binds with T and C binds with G. These bases are in three letter sequences called codons, for example a codon might be TAG it's anti codon is then ATC, because A bind with T and C binds with G. Let's say there is a big strand of DNA That is TAGTAGTAGTAGTAG, This is the codon TAG five times and the anti codon ATC five times.
We're done with anti-codons for a little while. We've got codons, which are awesome! (Sorry I really love biology)
Amino acids are what compose proteins. Proteins are incredibly big molecules made of lots of amino acids. Lets say TAG codes for amino acid X (there is no amino acid X, I'm just using a generic term). We then get amino acid X five times in a row from this piece of DNA..How'd we get that? Lets take a look.
DNA gets copied to mRNA (messenger RNA) first. In DNA we had A with T and C with G. In RNA there is no T, it's U instead. So, A with U and C with G. This means our DNA strand TAGTAGTAGTAGTAG's mRNA compliment is AUCAUCAUCAUCAUC.
mRNA goes to find tRNA (translation RNA) (it hangs out in in the ribosomes) This is where anti-codons come back. We've got our mRNA here, AUCAUCAUCAUAUC, it finds tRNA with it's anti codon, UAG. Right? because A binds with U and C binds with G. Exactly!
Sorry, I'm just so excited, we're making proteins!
mRNA only exists in these three unit anti-codons. So we need five mRNAs all with UAG. These mRNAs bring amino acid X (which I made up for convenience sake) and string five amino acid Xs together. In realith this would be millions of amino acids long, and there are twenty different known amino acids. Anyways this chain of amino acids, also called a polypeptide chain, is then folded into a protein. it's folded around things called histones - but you probably don't need to or want to know that. I hope this helps.
Posted by apramey on April 30, 2012 at 4:09 PM (Answer #2)
A DNA template cannot actually have uracil (U) in the base sequence because it has thymine instead of uracil. If we assume this is an mRNA sequence, then we can write the DNA sequence. For mRNA to DNA, we always pair A with T/U or pair C and G.
To find the complementary sequence, we look at each base and write its partner
For the complementary DNA strand. We can also write the complementary strand of tRNA which would look much like thias strand except replacing T with U since it is RNA.
Posted by mlsiasebs on April 29, 2012 at 11:12 PM (Answer #3)
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