Tuesday, November 25, 2008

THE DNA

In 1951, the then 23-year old biologist James Watson traveled from the United States to work with Francis Crick, an English physicist at the University of Cambridge. Crick was already using the process of X-ray crystallography to study the structure of protein molecules. Together, Watson and Crick used X-ray crystallography data, produced by Rosalind Franklin and Maurice Wilkins at King's College in London, to decipher DNA's structure. This is what they already knew from the work of many scientists, about the DNA molecule:
DNA is made up of subunits which scientists called nucleotides.
Each nucleotide is made up of a sugar, a phosphate and a base.
There are 4 different bases in a DNA molecule:
adenine (a purine)
cytosine (a pyrimidine)
guanine (a purine)
thymine (a pyrimidine)
By rule the number of purine bases equals the number of pyrimidine bases, which is known as Chargaff's Rule.
The number of A equals to T & G equals to C
The basic structure of the DNA molecule is helical and supercoiled, with the bases being stacked on top of each other. DNA can adopt a more compact configuration due to supercoiling. The degree of supercoiling in the cell is carefully controlled by the action of topoisomerases.

Click below for THE ORIGNAL WATSON AND CRICK'S PAPER ON DNA published in NATURE.

http://www.scribd.com/share/upload/14657893/107tm56i1nquox4cx6hm

Click below for CRICK'S ORIGNALVIEWS ON DNA

http://www.scribd.com/share/upload/14657985/1thxqzrgb62k0tiun4jd


DNA structure: Revisiting the Watson–Crick double helix by Manju Bansal

http://www.scribd.com/share/upload/14658063/bz1wet545h64o5t82eb

To go into the cell and have a virtual tour of it showing the DNA molecule click below

http://www.pbs.org/wgbh/nova/genome/media/journeyintodna.swf

Click here to build your own DNA molecule:

http://learn.genetics.utah.edu/content/begin/dna/builddna/

And if you want to extract a DNA online visit this virtual Lab:

http://learn.genetics.utah.edu/content/labs/extraction/

To extract DNA from almost anything in your Lab:

http://learn.genetics.utah.edu/content/labs/extraction/howto/DNA_Extraction.pdf