72 Chapter 4 (^)
(^) 5' end (^) Thymine (T) Adenine (A) (^)
O O^2
H
CH^3 H 3' end^
P
H
O H N N
2 O^ O^ 5'^ H^ 3'^
O N N
H N
N^ H^
CH^2
H H
(^)
(^) H H O N (^)
H^ H^ H^ H^ O H^2 C^
O^2
(^) H Cytosine (C) Guanine (G) O (^)
O O H H P^
O (^) O
P
H
N H O N H^
(^2) O O H^
H
N N
N
N
CH^2 O^ H^
N
H H
(^)
(^) H H O H N
H
(^) O H 2 C
H H
H
O^2
(^)
(^) H O (^)
O O Adenine (A) Thymine (T) P^
O^ O
P^ H^
H
2 O^ O^ N^ CH^3
N
CH 2 O
N H O
H H
(^)
(^)
H H N N H N N H (^)
H H (^) H H
(^) H H O
H
O^
O O H^2 C^
(^) Guanine (G)
Cytosine (C)
O O^2
(^) P H
O2 O N H^ H P^
N
H
(^) O
O
CH^2 O O^ H^ N^ H^
(^) H H N N H N N (^) H (^)
H H
H
H^ H^
3'^ N^ O^
H
H O H^2 C 5'^
(^)
(^) 3' end H
O^2
O (^)
P (^)
(^) O2 (^) O
5' end (^)
®^
(^) Sugar-phosphate Nitrogenous bases of the Sugar-phosphate
Lear ni ng^
backbone of^ two DNA strands connected^ backbone of^
Cen gage^
one DNA strand by hydrogen bonds complementary DNA strand
©^
Figure 4- 8 The hydrogen bonds between the purines and the pyrimidines and the chemical structure of a DNA
molecule.