Fundamentals of Molecular Biology - V.I. Rezyapkin 2009

Replication
General Characteristics of Replication

METABOLISM/36.html">DNA Replication begins at a specific site known as THE ORIGIN OF replication. Replication from this origin can proceed in either a unidirectional (Fig. 2.6 A) or bidirectional manner (Fig. 2.6 B).

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Fig. 2.6. Direction of replication fork movement from the origin of replication

The bacterial chromosome has a single origin of replication, meaning it constitutes a single unit of replication called a replicon; in other words, the bacterial chromosome is represented by a single replicon (Fig. 2.7)

Fig. 2.7. The bacterial chromosome is represented by a single replicon

Eukaryotic DNA contains multiple origins of replication, exhibiting a multireplicon (polyreplicon) Organization. Eukaryotic DNA replication continues until the replication forks from two adjacent origins of replication merge (Fig. 2.8).

Fig. 2.8. Polyreplicon Organization of Eukaryotic DNA

Both replicon size and Replication fork progression speed in eukaryotes are significantly smaller than in prokaryotes (Table 1).

Table 2.1.

Replicon Organization of Genomes

Organism

Number of replicons

Average replicon size, kb

Replication fork rate, bp/min

E.coli

1

4200

50000

Yeast

500

40

3600

Drosophila

3500

40

2600

Mouse

25000

150

2200


Last update: 12/08/2026

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