The Double Helix - Hydrogen bonding and stability

In summary, the most stable base pair is guanine-cytosine with three hydrogen bonds, followed by adenine-thymine with two hydrogen bonds. Cytosine-adenine is the least stable pair as it does not follow the complementary base pairing rule. The stability of a base pair is determined by the number of hydrogen bonds and the amount of energy required to break them. The more hydrogen bonds a pair has, the stronger and more stable it is.
  • #1
Vivianian
3
0
Rank the following base pairs according to their stability.
Rank from most to least stable. To rank items as equivalent, overlap them.

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I have found out that the first one is thymine-adenine pair and the second one is a cytosine-guanine pair. The third one is cytosine paired with adenine, which doesn't make sense, so it must be the least stable. Now how do I go about determining if the A-T pair or C-G pair is more stable? It has something to do with the number of bonds, maybe?
 
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  • #2
Vivianian said:
It has something to do with the number of bonds, maybe?

I think that is a safe assumption. Now just ask yourself which pair would require the most energy to break the hydrogen bonds; G-C with three H-bonds, or A-T with two H-bonds? This will be the most stable pairing.
 
  • #3
I know that the larger the bond energy, the more energy is needed to break the bond. If the more energy is needed to break the bond, that means the bond is stronger and more stable. Is this correct?
 
  • #4
Vivianian said:
I know that the larger the bond energy, the more energy is needed to break the bond. If the more energy is needed to break the bond, that means the bond is stronger and more stable. Is this correct?

Yep. Then just follow mplayer's advice and you should get the answer. I imagine them as being sticky: the more points (bonds) that can stick togeather, the more sticky the molecules are and the harder they are to pull apart!
 
  • #5
nobahar said:
I imagine them as being sticky: the more points (bonds) that can stick togeather, the more sticky the molecules are and the harder they are to pull apart!

That's a nice trick. Thanks for the advice! :)
 

1. What is the double helix structure?

The double helix structure is the shape of DNA, which consists of two intertwined strands that form a ladder-like structure. The strands are held together by hydrogen bonds between the complementary base pairs of adenine-thymine and guanine-cytosine.

2. How do hydrogen bonds contribute to the stability of the double helix?

Hydrogen bonds are weaker than covalent bonds, but they are numerous in the double helix structure. These bonds help hold the two strands of DNA together, providing stability to the structure. Additionally, the complementary base pairing ensures that the strands are held together in a specific and stable way.

3. What happens if there is a disruption in the hydrogen bonds?

If there is a disruption in the hydrogen bonds, the double helix structure may become unstable and unravel. This could lead to errors in DNA replication and potentially cause mutations. However, the body has mechanisms in place to repair any damage to the DNA.

4. Can other molecules besides DNA form a double helix structure due to hydrogen bonding?

Yes, other molecules such as RNA and proteins can also form a double helix structure through hydrogen bonding. However, the specific base pairing and sequence of DNA make it uniquely suited for storing and transmitting genetic information.

5. How does the strength of hydrogen bonds compare to other types of chemical bonds?

Hydrogen bonds are weaker than covalent bonds, which are the strongest type of chemical bond. However, they are stronger than van der Waals interactions and dipole-dipole interactions. This intermediate strength of hydrogen bonds allows for the stability of the double helix structure while also allowing for flexibility and ease of DNA replication.

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