How many base pairs in "twist" of double helix?

[matthatter]

I have a question about the double helix. Is there a specific number of base pairs in a full twist of the double helix? The "twist" requires one to view the double helix form one side. There will be some point where one strand crosses in front, so by "twist" I mean the length of the strands from that cross until that same strand again crosses in front of the other. In most pictures it looks like there are five base pairs for every "twist".

 

Does it vary depending on the DNA? Is there a human average?

 

This question may be completely ridiculous, I don't know much about DNA and I haven't managed to find this information.

 

Thanks for any help!

[Essay]

I googled: DNA twist angstrom

 

Looks promising; here's an example:

 

DNA Spiral

2. How many bases are included in each twist of the DNA molecule?

-----------------

The Watson and Crick structure of DNA sometimes called B-DNA...yes there

are different forms of DNA...the real story in biology is always more

complex...this is the most recognized form of DNA, partly because the

pattern it produces in images using x-rays resembles the DNA we find in

sperm. This being said, here are some of the dimensions of B-DNA

...

 

* Its diameter across the helix is about 20 angstroms

 

* It has ten base pairs for every complete twist of the double helix

 

* The helix has a rise of 34 angstroms for every complete 360 degrees of turn

 

* Since the helix is not the simplest twist that is often shown in secondary school books of cheap models, but what I think of as a helix upon a helix, the indentations of the helix are unequal and there is a deep or major groove and a shallow or minor groove. For a decent model go to:

DNA structure

 

...hope this helps.

~ :phones:

[matthatter]

Wonderful! :phones: Thanks so much, Essay.