• The sugar puckering in A-DNA is 3'-endo.

• The Sugar and base conformations in Z-DNA alternate: 
  In the Z-DNA duplex, d(5'-GCGCGCGCGCGCG-3')/d(3'-CGCGCGCGCGCGC-5'), C:sugar is 2'-endo, base is anti and G: sugar is 3'-endo, base is syn.

4.10.4.7. B-type Duplex is not Possible for RNA

Although B-DNA solved by Watson and Crick is the major form of DNA in chromosomes, other types of secondary structure are possible. For example, duplexes containing RNA cannot form B type duplex because of the steric clash between its 2'-OH and the phosphodiester. Instead, it forms an A-type duplex.

4.10.4.8. SOME OTHER TYPE OF BASE PAIRING AND DNA SECONDARY STRCTURE

4.10.4.9. WOBBLE BASE PAIRS AND RNA SECONDARY STRUCTURE