Copy the diagram and use dotted lines to indicate where hydrog...

Question

Copy the diagram and use dotted lines to indicate where hydrogen bonding occurs between the complementary strands of DNA. What is the sequence of each strand of DNA drawn (remember that the sequence is written from the 5′ to 3′ end)?

Accepted Answer

All right. Hi, everyone. So this question is asking us to use dotted lines to show the points where hydrogen bonds are formed between the complementary strands of DNA. What is the five prime to three prime nucleotide sequence of the following DNA strand? All right. So here we have a little diagram of double stranded DNA. And when looking at the directionality of a given strand, we are reading it from top to bottom. So because of that, we can see that on the left is the five prime to three prime strand. And on the right is its complement going from three prime to five prime instead. Now, because the DNA is a nucleic acid recall that it's composed of nucleotide monomers. Now nucleotides themselves have three components to them on the outside of the DNA strand are the sugar molecule and phosphate group, whereas in the interior are the nitrogenous bases. Now, it's the identity of the base that distinguishes nucleotides from each other. And these bases are once again found in the interior of the double helix or of the double stranded DN. It. Now what stabilizes the structure of double stranded DNA and helps to produce the characteristic double helix is the fact that complementary bases, which we will discuss in more detail in a moment hydrogen bond with each other. Now, what does it mean when we say that bases are complementary? Well, what we notice in DNA as a whole and also Arne is that we only see specific nucleotide bases binded with specific other bases. For example, adenine in DNA is known only to bind with thymine. Whereas cytosine is only known to bind with guanine. Now, adenine and guanine are known as purine bases that have two fused rings, thiamine and cytosine. However, are pyrimidines with only one ring. So based on the structural characteristics of each base, we can identify them in this strand. So take here for example, the first base of the five prime strand here, we can see that it's only composed of one ring. So it must be a pid and that Pym contains a methyl group as well as two Carbonis. This identifies this particular base as thymine, which means that thymine must be bonding with Adam. And we can identify the base to its right as adenine because of the fused two rings and the amino group here, the NH two moving on. Now to the next one, we can see that the next base of the five prime strand is adenine because of that same two fused ring structure and the amino group, this means that adenine or excuse me, thymine is next to it. Now, the third base on the other hand, from the five prime strand is also a one ring or also a single ring. So it's a perimeter this time. However, the pyrimidine base contains an amino group. So that's cytosine, which means that right next to it must be Guan and we can identify it as guanine because it contains two fused rings and a car bottle last but not least in the five prime to three prime strand, we have a purine base with two fused rings containing a car bono which identifies it as guanine, meaning cytosine is next to it. Now, before we talk about hydrogen bonding, we can actually address that next part of the question because the five prime, the three prime sequence has already been determined and that's T ac G that's thymine, adenine, su cyta and guanine. So now let's talk about h bonding. Now, depending on the specific base pair, the hydrogen bonding is going to look a little bit different. For example, Adenine and thymine have two H bonds, whereas cytosine and guanine have three. So let's start off with the A and T base pair for thymine and adenine first, we have the ketone group of thymine hydrogen bonding with the NH two of adenine because recall that hydrogen bonding is a very specific interaction between two compounds. This is when an electron atom is interacting with a hydrogen that is itself attached to another electron atom. So we have the carbon oxygen, an electron atom interacting with the hydrogen of the NH two that is connecting to the electron nitrogen. So for the second hydrogen bond, the hydrogen of the NH group of thymine is going to hydrogen bond with the nitrogen of adenine that is embedded in the ring structure make up. So now let's talk about cytosine and guanine, cytosine and guanine have three balls. So first, we have the carbonel group of guanine hydrogen bonding with a hydrogen from the NH two of cytosine like. So up next, we have the hydrogen of the NH group in guanine hydrogen bonding with the nitrogen of the six member ring of cytosine. And last but not least we have the carbonel group from cytosine hydrogen bonding with the NH two of Guan. And so from here, we can add these same interactions now to the other cytosine guanine pair and we can add the same bonds as before to the other adenine thymine pair. And there you have it. Now, just for the sake of clarity, I'm going to go ahead and erase the labels that I had made before. And so here is our completed final answer. And so with that being said, thank you so very much for watching. And I hope you found this helpful

Copy the diagram and use dotted lines to indicate where hydrogen bonding occurs between the complementary strands of DNA. What is the sequence of each strand of DNA drawn (remember that the sequence is written from the 5′ to 3′ end)?

Key Concepts

Hydrogen Bonding in DNA

DNA Strand Orientation

Complementary Base Pairing

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