1. Chapter 21 Nucleic Acids and Protein Synthesis
21.4 DNA Replication

2. DNA Replication DNA replication involves unwinding the DNA
pairing the bases in each strand with new bases to form new complementary strands
producing two new DNA strands that exactly duplicate the original DNA

3. Hydrolysis Energy Energy
from the hydrolysis of each nucleoside triphosphate
is used to form a phosphodiester bond to each new nucleotide on the complementary strand

4. Direction of Replication
During DNA replication,
an enzyme, helicase, unwinds the parent DNA at several sections
at each open DNA section (called a replication fork), DNA polymerase catalyzes the formation of 5′–3′ ester bonds of the leading strand
the lagging strand (growing in the 3′–5′ direction) is synthesized in short sections called Okazaki fragments
DNA ligase joins the Okazaki fragments to give a single 3′–5′ DNA strand

5. Direction of Replication (continued)

6. Learning Check Match the following: 1) helicase 2) DNA polymerase
3) replication fork 4) Okazaki fragments
A. short segments formed by the lagging strand
B. the starting point for synthesis in unwound DNA
sections
C. the enzyme that unwinds the DNA double helix
D. the enzyme that catalyzes the formation of
phosphodiester bonds of complementary bases

7. Solution Match the following: 1) helicase 2) DNA polymerase
3) replication fork 4) Okazaki fragments
4 A. Short segments formed by the lagging strand.
3 B. The starting point for synthesis in unwound DNA sections.
1 C. The enzyme that unwinds the DNA double helix
2 D. The enzyme that catalyzes the formation of phosphodiester bonds of complementary bases