How are the two strands of nucleic acid in DNA held together?

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Alright. Hello everyone. So this question is a true or false if false, correct the statement, the two strands of nucleic acid and DNA are held together by ionic bonds between their phosphates. Option A is true. And options BC and D say the statement is false with potential corrections for the in intermolecular force holding these two strands together. B mentions covalent bonds. C mentions hydrogen bonds and D mentions Vander Waals forces. So first for your reference, I went ahead and pre drew the structure of a nucleotide. So here is a basic example nucleotide and the reason why I went ahead and drew it is just to go ahead and talk about the main components of a nucleotide. First is the sugar backbone. Now, when it comes to RN A, the sugar backbone is going to be ribose with a hydroxy group. On position number two, if we're talking about DNA, it would be deoxyribose with a hydrogen on position two. Instead. Now on carbon number one of our sugar backbone is a nitrogenous base which is just nitrogen connecting to the sugar. And then we have the structure of an aromatic base. There's going to be another hydroxy group on carbon number three, which is true for both rivals and deoxy rivals. And then finally, there is a phosphate group connecting to carbon number five via a phosphate ester bond. So here, right, what do we know about the basic structure of DNA? Well, recall that it's the nitrogenous bases that are involved in stabilizing the double helix structure of DNA. Because recall that we talk about base pairing rules when understanding the structure of DNA. For example, we know that in DNA, adenine pairs with thymine and vice versa, and cytosine pairs with guanine and vice versa. Now here these interactions, right, these base pairs that we just mentioned are held together by H bonds or by hydrogen bonds. So, admin and thymine have two H bonds holding them together, whereas cytosine and guanine have three H bonds being or holding them together. So just to go ahead and summarize, it's the H bonds between these complementary bases that hold the structure of DNA together, they are what stabilized the double helix strand where both strands run in opposite directions. So really recall that the bases would be on the inside, right? They would be in that space between the two backbones themselves, the backbones of two strands, I mean the phosphate group would actually be on the outside. So they're not involved in stabilizing the structure. So bottom line is that the statement given is false because it's actually the f the excuse me, hydrogen bonds between nitrogenous bases that holds the two strands of nucleic acid and DNA together. So our answer is going to be option C and so with that being said, thank you so very much for watching. And I hope you found this helpful.

How are the two strands of nucleic acid in DNA held together?

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Key Concepts

Base Pairing

Hydrogen Bonds

Double Helix Structure