(Solved) Are the bonding angles between nitrogen bases different on each side of the DNA?

BossMan300

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9 years ago

Are the bonding angles between nitrogen bases different on each side of the DNA?

Are the bonding angles between nitrogen bases different on each side of the DNA?
Take a look at the drawing attached. I put in arrows on the angles of interest. One arrow is red with black filling; the other arrow is orange with black filling.

What do you think!?

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bio_man

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9 years ago

The DNA molecule twists like a double-ladder. I think the angle remains consistent. Some sources state that every base has a 36° angle of rotation. The radius of the double helix is approximately 10 Å.

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BossMan300 Author

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9 years ago

Take a look at this picture. I believe I was able to see the 36 degree rotation angle you were talking about.
But, I am interested in the angle between nitrogen and oxygen - shown in lime green - on the two chains, they seem to be different.

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ortho2122

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9 years ago Edited: 9 years ago, ortho2122

The diagram is a 2D projection of a 3D object. The view distorts things. You can't use a protractor to measure the bond angles, at least not from such an image as this. It isn't trying to accurately represent that kind of information. I had to chuckle at your measurement of the 36 degree angle. You wouldn't be able to find that angle if you walked up to a 3D model. The bond angles between the base and the ribose rings vary slightly, but not by all that much.

The 36 degree thing is the rotation of each successive base pair relative to the next base pair. Imagine looking down the helix with a base pair laying horizontally. Now imagine rotating the base pair by 36 degrees and translating along the axis of the helix by 0.34 nm and you will be sitting on top of the next base pair. If you do that roughly 10 times you will have rotated through one turn of the helix and moved something like 3.4 nm along the axis.

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BossMan300 Author

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9 years ago

Thanks for your reply. 36 degrees, 10 nucleotides necessary to complete a full rotation.
36*10=360 Degrees. That makes sense.

I was going to attach a 3D representation of DNA, but I decided to draw the crazy picture attached. My aim was to show 10 nucleotides at a 36 degree nucleotide-to-nucleotide deviation from the tangent. I believe this would cause a complete rotation, but my diagram doesn't testify to that: I only got a little past half way through the rotation. Nonetheless, I think it still illustrates the idea.

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ortho2122

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Are the bonding angles between nitrogen bases different on each side of the DNA?

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