Bond Strength in DNA

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Aishwarya Kosgi 1F
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Bond Strength in DNA

Postby Aishwarya Kosgi 1F » Thu Nov 19, 2020 11:31 pm

Hi! I had a question about AT and GC pairs in DNA. Since AT base pairs have only 2 hydrogen-bonding sites and GC has 3 hydrogen bonding sites, is GC stronger? Or are the bond strengths of AT and GC pretty comparable because they both are able to hydrogen bond? I was wondering if that 3rd h-bond in GC makes a big difference? Thank you!

Victor Li 2A
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Re: Bond Strength in DNA

Postby Victor Li 2A » Fri Nov 20, 2020 1:05 am

You are correct that G-C DNA bond pairs are stronger since they have 3 hydrogen bonds. This is also why DNA strands that are rich in G-C base pairs require higher temperatures to be denatured.

Kristina Krivenko 3I
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Re: Bond Strength in DNA

Postby Kristina Krivenko 3I » Fri Nov 20, 2020 1:06 am

I'm not sure by how much but G-C pair is definitely stronger since, as you mentioned, G-C pair can form 3 hydrogen bonds whereas A-T pair can form only 2. In his lectures, Dr. Lavelle mentioned that the effect of IMFs adds up, and, thus, G-C pairs are more stable.

Navdha Sharma 3J
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Re: Bond Strength in DNA

Postby Navdha Sharma 3J » Fri Nov 20, 2020 7:41 am

G-C bonds are stronger as they are triple bonds while A-T bonds are only double bonds. Due to larger bond strength, G-C bonds are more stable too.

AnjikaFriedman-Jha2D
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Re: Bond Strength in DNA

Postby AnjikaFriedman-Jha2D » Fri Nov 20, 2020 9:54 am

The ability to form 3 hydrogen bonds compared to 2 bonds would make G-C base pairs both stronger and more stable

Tobie Jessup 2E
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Re: Bond Strength in DNA

Postby Tobie Jessup 2E » Sun Nov 22, 2020 11:59 am

The strength of intermolecular interactions increase with the number of individual interactions/bonds, so the 3 hydrogen bonds in G-C bonding makes them strong than A-T bonding which only has 2 hydrogen bonds.

Gustavo_Chavez_1K
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Re: Bond Strength in DNA

Postby Gustavo_Chavez_1K » Sun Nov 22, 2020 12:27 pm

Yeah so since the G-C pair has 3 hydrogen bonds in comparison to A-T which only has 3, G-C pairs would be considered both stronger and more stable. Also, this would explain why G-C pair bonds need higher temperatures to be denatured.

Joey_Okumura_1E
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Re: Bond Strength in DNA

Postby Joey_Okumura_1E » Sun Nov 22, 2020 12:47 pm

Recall that for intramolecular forces, multiple bonds are stronger than single bonds. The same concept applies to intermolecular bonds. The strength and quantity are directly related.

Yuehan_Wu_3K
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Re: Bond Strength in DNA

Postby Yuehan_Wu_3K » Sun Nov 22, 2020 7:38 pm

GC bonds are much stronger because they have three hydrogen bonds connected while AT bonds only have two linked hydrogen bonds.

Melanie Lin 3E
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Re: Bond Strength in DNA

Postby Melanie Lin 3E » Sun Nov 22, 2020 9:10 pm

That's correct! With more hydrogen bonds, GC pairs are markedly stronger than AT pairs. So DNA with low GC ratio often times are less stable compared to DNA with high GC ratio!

Arnav Saud 2C
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Re: Bond Strength in DNA

Postby Arnav Saud 2C » Sun Nov 22, 2020 11:55 pm

GC is stronger than AT because it has one extra h bond.

vanessanguyen3I
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Re: Bond Strength in DNA

Postby vanessanguyen3I » Mon Nov 23, 2020 12:00 am

GC is stronger because it has an extra hydrogen bond. This means that more heat is needed to break the bonds between GC versus the bonds between AT.

Gabriel Nitro 1E
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Re: Bond Strength in DNA

Postby Gabriel Nitro 1E » Mon Nov 23, 2020 9:17 am

Hi,

Yes! That is correct! The additional hydrogen bond makes the GC attractions stronger!

Hope this helps! :)


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