
Concept explainers
Interpretation:
Complementary base pairing between two individual strands of DNA must be described that forms the overall double helical structure. The involvement of complementary base pairing during replication of DNA must also be explained.
Concept Introduction:
DNA is the

Answer to Problem 34A
Two individual strands of DNA participate in hydrogen bonding to make the overall double helical structure of DNA.
During replication the base pairing is temporarily lost to unwind the DNA for daughter DNA strands generation.
Explanation of Solution
DNA has one aldopentose sugar which is 2-Deoxy-D-Ribose. Nitrogenous bases are Adenine (A, purine), Guanine (G, purine), Cytosine (C, pyrimidine) and Thymine (T, pyrimidine). There is one phosphate group. Between two strands there are hydrogen bonds.
A forms two hydrogen bond with T and G forms three hydrogen bonds with C as shown in the figure below. Thus the overall double helical structure of DNA is formed.
During replication the two DNA strands are separated. The hydrogen bond is not there now. The two individual strands now acts as a template and DNA polymerase helps to add the
Chapter 21 Solutions
World of Chemistry
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