DNA, Gene Structure, and DNA Replication - Insect Molecular Genetics - page 22

Figure 1.12 DNA replication occurs in a different manner on the two strands. A) The leading strand
is continuously copied, with synthesis occurring in the 5 ′ to 3 ′ direction. B) Synthesis on the lagging
strand is discontinuous because the DNA strands are antiparallel. Synthesis occurs in short segments
(Okazaki fragments) because DNA polymerase can only synthesize DNA in the 5 ′ to 3 ′ direction.
Figure 1.13 A) DNA must be primed so that DNA polymerase is able to synthesize a complementary
strand. B) A primer of ribonucleotides is attached to a strand by RNA polymerase. DNA polymerase
can then attach deoxyribonucleotides (dNTPs) to the DNA template in a sequence that is determined
by the template strand (complementary base pairing). DNA synthesis occurs in the 5 ′ to 3 ′ direction.