Draw the dinucleotide AT that would be found in DNA. Label the 5' and 3' ends of your structure. Identify the phosphodiester bond.

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Accepted Answer

Hi, everybody. And welcome back. Our next question says, draw the correct structure of the di nucleotide CT found in DNA, ensure the five prime and three prime ends are labeled. And the phospho Ditra bond between cytosine and thiamine is correctly identified. So we have a dinucleotide with cytosine C and thymine t linked by a phosphoria bond. And so our first step, we'll start with cytosine, we need to remember what does that nucleotide base look like. So for cytosine and thymine, they're both periman. So six membered rings and both of them have nitrogens in their ring at positions one and three. So draw that ring with the nitrogens in it. And then for cytosine, there are double bonds between carbon six and then the nitrogen at position one and then between carbons four and five, then on carbon six or it's not carbon sex, position six in the ring, I should say, since there's not six carbons in the ring, there's an NH two group. And then on the carbon at position two, there's a double bond to an O. So a carbon group and then the nitrogen at position three is where we bond to the deoxyribose ring. So just bring that wind down and then we're going to draw our deoxyribose ring. So it's a Furano a five membered ring. So we put our oxygen at the top and the anomic carbon is what is linked to our base there. So base is extending up above the plane of the ring, draw the rest of our ring here. So it's kind of weird looking. And then coming down below the plane of the ring is a hydrogen. I will put the hydrogens on here to emphasize that this is a deoxyribose r and not a rising. So what makes it deoxyribose is then at carbon two in our sugar ring instead of a hydroxyl group, we have two hydrogens on that carbon and then we come to carbon three has a hydrogen above the plane of the ring and a hydroxyl group going down except that hydroxyl group. This is carbon three. This is where the phosphor Dior bond will be. So we'll draw just o and then we'll continue that into the phospho Dior bond to our thyme. Let's just finish off our deoxy rus. On carbon four, we have a hydrogen below the plane of the ring and then carbon five above it. So write CH two and then instead of C H2O H, this is where the phosphate group is. So we have ch two bonded to a phosphate group here. So op and then the P has a double bond to an O on top and then to single bonds to O minus. So that's our phosphate group. And then this would be our five prime because that is carbon five there coming up out of the ring. So we have the fire prime in the base, the sugar we just need then the depiction of our phosphor Dior bond to the thymine. So we have that oxygen extending below the ring at carbon three. So let's extend that into a phosphate group. So the oxygen, it's linked to a phosphate, it's linked to a P, just a double bond to an O above single bond to o minus below single bond to another oxygen. And then that oxygen is going into the five prime end of the next deoxyribose. So from that oxygen, a bond to ch two. So carbon five of our thymine, and then we'll draw our deoxyribose ring. Sorry, my rings are looking a little weird there. And so that's onto carbon four there. And then carbon three, we'll have a hydrogen going above the plane of the ring and just a hydroxyl group. This is the end of our dinucleotide. So there's no phosphate group there. That's the end. And this is the three prime end here. There's a three prime hydroxyl group. So we've got the phosphate, the deoxyribose, we just need the, the uh base for our thymine here. So we'll draw that bond to the anomic carbon hydrogen down below. And again, a perimeter ring. So the link is to the nitrogen at position three and draw the ring another nitrogen at position one. And then in the case of thymine, we have a double bond from carbon 4 to 5, the methyl group coming out at carbon five, a carbonel group of carbon six and then a carb group at carbon two. So that's thymine. So we'll write cytosine first one diamine on the second and check that we've labeled everything that's supposed to be labeled. So it says, ensure the five prime and three prime ends are labeled. So we did that five prime N being me on the cytosine and three prime N being on the thymine. And then it says that the phospho Ditra bond between cytosine and thymine is correctly identified. So that phospho disaster bond is coming down from carbon three, that oxygen linked to the phosphate group. So that is our phospho ester bond. So there we have it are dinucleotide CT with the cytosine and thymine and it's five prime, three prime ends labeled and its phospho Dior bond be in the next video.

Draw the dinucleotide AT that would be found in DNA. Label the 5' and 3' ends of your structure. Identify the phosphodiester bond.

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Key Concepts

Dinucleotide Structure

5' and 3' Ends

Phosphodiester Bond