Consider a DNA coding strand with the following sequence: 3'-C...

Question

Consider a DNA coding strand with the following sequence: 3'-C T T C A T A G C T C G-5'.

Use the genetic code to determine the corresponding amino acid sequence of the translated protein.

A genetic code table showing DNA, mRNA, and protein sequences for biochemistry.

Accepted Answer

So this practice problem wants us to consider a DNA coding strand with the following sequence from 3 prime to 5 prime and to use that information along with the genetic code below to determine the corresponding amino acid sequence of the translated protein. And so down below, we have the DNA coding strand rewritten exactly as it's shown up above. And so to get the mRNA strand, we're going to need to use our base pairing rules, where c's base pair with g's, t's with a's. Right? No, Not right. So recall that the base pairing rules here would only be used if we're given a template strand, but we're given a DNA coding strand. So the mRNA strand, remember, uses the template strand and base pairing rules to build the strand. But, the coding strand, recall, is exactly the same sequence as the mRNA strand, except all of the thymines are replaced with uracils. So we can rewrite the exact same sequence, except replacing the t's with u's. So when we do that, we get this sequence here, u c g. So it's exactly the same as the one above, except the t's are replaced u's. And so the directionality stays exactly the same. So this is still the 3 prime and this is still the 5 prime. So now we're able to jump straight into our genetic code. And here's our first codon, C U U. So we can jump straight in and use our genetic code, right? No, not right. So recall that the genetic code includes the directionality of the mRNA strand, and that we need to make sure we're reading our mRNA strand from the 5 prime end to the 3 prime end. But because as shown it's from 3 to 5 prime, then we need to rewrite our sequence with the orientation flipped. So essentially reading off the sequence in this direction. So when we do that, we get GCUCGAUACU c. And the directionality has not is, I'm sorry. The directionality has been flipped. So this is the 5 prime, this is the 3 prime, but this is still the same exact RNA molecule. So now that we have GCU as our first codon, we can now apply the genetic code. So recall how to use the genetic code from our previous videos, and GCU gives us an alanine amino acid. CGA is the next codon, which gives us a CGA, gives us an arginine amino acid. UAC is the 3rd codon, and UAC gets us a Tyrosine amino acid. And then UUC is a final amino, final codon, and UUC gets us phenylalanine. And so these are the 3 letter abbreviations for those amino acids, and technically, this is the answer to our problem. However, recall that the proteins that are built have directionality as well. And so over here on this end, closer to the 5 prime end, will be the n terminal of the protein that has a free amino group. And on the opposite end, we have the c terminal end, closer to the 3 prime end of the mRNA sequence. And so the answer to our problem is highlighted in green below, alanine, arginine, tyrosine, phenylalanine, and I'll see you guys in the next video.

Struggling with Biochemistry?

Consider a DNA coding strand with the following sequence: 3'-C T T C A T A G C T C G-5'.
Use the genetic code to determine the corresponding amino acid sequence of the translated protein.

Watch next

Central Dogma practice set

Struggling with Biochemistry?

Consider a DNA coding strand with the following sequence: 3'-C T T C A T A G C T C G-5'.Use the genetic code to determine the corresponding amino acid sequence of the translated protein.

Watch next

Central Dogma practice set

Consider a DNA coding strand with the following sequence: 3'-C T T C A T A G C T C G-5'.
Use the genetic code to determine the corresponding amino acid sequence of the translated protein.