1. DNA Structure
Watson and Crick Model

8.  Characteristic
Forms of DNA A B C Z
Condition required to produce
75%H2O
92%H2O -
66%
Overall shape
Short & broad
Long &thinner
Elongated& slim
Helix direction
Right handed
Right-handed
Left handed
Helix diameter
26A0
20A0
19A0
18A0
Bases/3600 turn
11.0
10.0
9.3
12.0
Repeating unit
1 bp
1bp
2 bp
Rotation/bp
34.70
340
38.6
-300
Mean bp/turn
10.7 12
Inclination of bp to axis
+190
-1.20
-90
Rise/bp along axis/
2.56 A0
3.38 A0
3.32 A0
5.71 A0
Pitch/turn of helix
24.6 A0
33.2 A0
45.6 A0
Mean propeller twist
+180
+160 0°
Glycosyl angle
Anti
anti
C: anti, G: syn
Sugar pucker
C3'-endo
C2'-endo
C: C2'-endo, G: C2'-exo

10.  Characteristic
Forms of DNA A B C Z
Condition required to produce
75%H2O
92%H2O -
66%
Overall shape
Short & broad
Long &thiner
Elongated& slim
Helix direction
Right handed
Right-handed
Left handed
Helix diameter
26Å
20Å
19A
18Å
Bases/3600 turn
11.0
10.0
9.3
12.0
Repeating unit
1 bp
1bp
2 bp
Rotation/bp
34.7°
34°
38.6
-30°
Mean bp/turn
10.7 12
Inclination of bp to axis
+19°
-1.2°
-9°
Rise/bp along axis/
2.56Å
3.38Å
3.32 Å
5.71Å
Pitch/turn of helix
24.6Å
33.2Å
45.6Å
Mean propeller twist
+18°
+16° 0°
Glycosyl angle
anti
C: anti, G: syn
Sugar pucker
C3'-endo
C2'-endo
C: C2'-endo, G: C2'-exo