Chapter 6.2: Watson and Crick Model of DNA

Helical molecule with regular repeats

The X-pattern in X-ray DNA is characteristic of what

Maurice Wilkins and Rosalind Franklin

Cristallographers that developed methods to produce diffraction patterns of DNA

Nucleotides

Dna is a long polymer composed of subunits called

A and G

purines

C and T

Pyrimidines

Nucleoside

Covalent attachment of a nucleobase to the 1’ carbon of deoxyribose forms:

polarity

The DNA polymer has a direction, or:

5’-3’

Dna is described in terms of its bases writeen in this directioN:

Two DNA chains spiral around an axis with the sugar phosphate backbone on the outside and flat pairs of bases meeting in the middle

Watson and Crick model for DNA

ratio of A to T and C to G are 1:1. A pairs with T and C pairs with G

Chargaff’s rule:

2 noncovalent hydrogen bonds

A-T involves what bonds:

3 hydrogen bonds

G-C pairing involves what bonds

Major and minor groove

Two backbones are vertically displaced from eachother, generating two grooves:

Spirals to the right, B DNA

majority of naturally occuring DNA spirals in this direction

left, Z DNA

DNA spirals in vitro