a dna and z dna atlases n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
A-DNA and Z-DNA Atlases PowerPoint Presentation
Download Presentation
A-DNA and Z-DNA Atlases

Loading in 2 Seconds...

play fullscreen
1 / 31

A-DNA and Z-DNA Atlases - PowerPoint PPT Presentation


  • 152 Views
  • Uploaded on

A-DNA and Z-DNA Atlases. Dave Ussery Comparative Microbial Genomics first lecture, 18 September, 2002. Outline. Helix family. A-DNA. A-DNA helix. A-DNA was the first DNA helix characterised by Rosalind Franklin in the early 1950’s. A-DNA helices

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'A-DNA and Z-DNA Atlases' - hallam


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
a dna and z dna atlases

A-DNA and Z-DNA Atlases

Dave Ussery

Comparative Microbial Genomics

first lecture, 18 September, 2002

a dna helix

A-DNA

A-DNA helix

A-DNA was the first DNA helix

characterised by Rosalind Franklin

in the early 1950’s. A-DNA helices

tend to be favoured by stretches of

purines (or pyrimidines) of at least 4 bp.

A-DNA helices are found in RNA-DNA

hybrids.

b dna helix

B-DNA

B-DNA helix

B-DNA is the `classic´ helix described

by Watson and Crick in 1953. It has,

on average, about 10 bp/turn of the helix

and is the AVERAGE structure for many

DNA sequences.

z dna helix

Z-DNA

Z-DNA helix

Z-DNA was the first DNA helix to be crystallised

(in 1979), and came to the surprise of many biologists.

It is a thin, LEFT-HANDED helix, with 12 bp/turn,

and has a zig-zag backbone (hence its name). Certain

alternating pyrimidine/purine sequences

(e.g., CGCGCG) will form this helix.

how random is dna
How Random is DNA?

Consider a stretch of purines (G or A, abbreviated R)

of length n:

What is the probability of finding this in a random DNA

sequence?