Hydrogen bonding in Cytosine and Guanine

In summary, the conversation discusses the concept of hydrogen bonds and how they form between certain atoms. It is stated that in the cytosine-guanine base pair, there is a hydrogen bond between an oxygen atom and NH2, although the oxygen atom is only bonded to carbon. This is explained by the fact that oxygen, fluorine, or nitrogen atoms with available lone pairs can serve as hydrogen bond acceptors, and any hydrogen bonded to these atoms can serve as a hydrogen bond donor. It is also mentioned that carbon dioxide does not form hydrogen bonds due to its lack of hydrogens and its non-polar nature. Overall, the conversation highlights the importance of certain atoms and their ability to form hydrogen bonds in the context of molecular structure.
  • #1
staralfur
11
2

Homework Statement


The problem was to tell how many hydrogen bonds there are between cytosine and guanine. and I know there are three. http://study.com/cimages/multimages/16/Cytosine_Guanine_base_pair.png
But I think I might be misunderstanding the hydrogen bond concept.
I thought that hydrogen bonds only formed between O, F and N when they are also bond to H atom. And therefor CO2 fx does not form hydrogen bond with water as the oxygen atoms in the CO2 are not bonded to H atom.
In the cytosine-Guanine there is a hydrogen bond between Oxygen atom and NH2 but the Oxygen atom is only bond to Carbon, so why is there a hydrogen bond?
And N makes hydrogen bond with NH but the N is only bond to two C atoms
please explain.
 
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  • #2
Oxygen, fluorine or nitrogen atoms with available lone pairs can usually serve a hydrogen bond acceptor, and any hydrogen bonded to an F, O, or N can serve as a hydrogen bond donor. CO2 lack hydrogens, so it cannot serve as a hydrogen bond donor. Although it has free lone pairs on its oxygens, CO2 does not serve as a hydrogen bond acceptor because the molecule is not polar. The molecule is linear, so the dipoles from the two C=O bonds cancel each other out, and the molecule carries no net dipole (although, I'm not sure this explanation is entirely correct, because some sources I've found do suggest that carbon dioxide is capable of forming hydrogen bonds). Nevertheless, in guanine and cytosine, the oxygen atoms do carry a net dipole moment and can act as hydrogen bond acceptors.
 
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Related to Hydrogen bonding in Cytosine and Guanine

What is hydrogen bonding in Cytosine and Guanine?

Hydrogen bonding in Cytosine and Guanine is a type of chemical bonding between the nitrogenous bases cytosine and guanine in DNA. It involves the attraction between a hydrogen atom and a nitrogen or oxygen atom in the bases.

Why is hydrogen bonding important in Cytosine and Guanine?

Hydrogen bonding is important in Cytosine and Guanine because it helps to hold the two DNA strands together in a double helix structure. This is essential for the stability and replication of DNA.

How many hydrogen bonds are formed between Cytosine and Guanine?

Three hydrogen bonds are formed between Cytosine and Guanine. This is because Cytosine and Guanine have complementary base pairing, where Cytosine always pairs with Guanine and vice versa.

Can hydrogen bonding occur between other nitrogenous bases in DNA?

Yes, hydrogen bonding can also occur between adenine and thymine in DNA. Adenine and thymine form two hydrogen bonds, while cytosine and guanine form three hydrogen bonds.

How does the presence of hydrogen bonding affect the stability of DNA?

The presence of hydrogen bonding greatly increases the stability of DNA. Without hydrogen bonding, the double helix structure would not be able to hold together and the genetic information in DNA would be easily disrupted.

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