Watson and Crick model is for
DNA
mRNA
rRNA
tRNA
Watson and crick model Double helical structure of DNA.Adjacent bases are seperated by 0.34nm. The diameter or width of the helix is 2 nanometers. Phosphate bonds form the rail of stair case. Bases jutting inside form the steps of staircase. REF :DM VASUDEVAN TEXTBOOK;8th EDITION ;Page no 557.
Metabolism of nucleic acids