16.2-1CC - Campbell Biology

Question

What role does complementary base pairing play in the replication of DNA?

Step-by-Step Solution

Answer

During DNA (Deoxyribonucleic acid) replication, two molecules of DNA are synthesized. Complementary base-pairing ensures that the two DNA molecules synthesized are identical to the parental DNA molecule.

Step 1: Structure of DNA

DNA comprises two strands that are made up of nucleotides. Nucleotides are composed of a nitrogen base, a pentose sugar, and a phosphate group. Purine and pyrimidine are two types of nitrogen bases found in DNA. 

In the DNA molecule, the nitrogen bases of the two strands pair with one another. The pairing between the nitrogen bases of the two strands occurs through hydrogen bonding. 

This base pairing between the strands is referred to as complementary base pairing.

Step 2: DNA replication

A replication process leads to the doubling of DNA molecules in the cell. The synthesized DNA molecules are the same as that of the parent cell. This process is known as DNA replication.

During DNA replication, the two strands of DNA separate. These separated strands act as a template on which a new strand of DNA is synthesized through complementary base pairing. Thus, the two strands of DNA molecule are complementary to each other.

Step 3: Importance of complementary base pairing

Replication necessitates the use of a template as it provides sequence information. Because each strand complements the other, they can be separated and used as a template for creating a new strand.

Because half of the parent DNA molecule is conserved in each new DNA molecule, paired with a newly synthesized complementary strand, this is referred to as semi-conservative replication. 

Thus, complementary base-pairing ensures that the DNA molecules synthesized are replicas of the parent DNA molecule.