BME 130 – Genomes Lecture 21 Genome replication

Figure 15.1 Genomes 3 (© Garland Science 2007) Genome replication Each strand of double helix serves as template for a new copy Problems?

Figure 15.2 Genomes 3 (© Garland Science 2007) Proposed models for DNA replication

Figure 15.3a Genomes 3 (© Garland Science 2007)

Figure 15.3b Genomes 3 (© Garland Science 2007)

The topological problem

Variations on the theme

Mitochondrial DNA replication

Rolling circle replication (lamba phage)

Replication origin in E. coli Found by testing sequence regions for ability to replicate associated DNA

Remain attached to DNA throughout cell cycle

Elongation

New bases are added to free 3’ OH groups in a template-directed fashion

Replication requires a free 3’ –OH and is going in two different directions!

Table 15.2 Genomes 3 (© Garland Science 2007)

Figure 15.15a Genomes 3 (© Garland Science 2007)

Figure Genomes 3 (© Garland Science 2007) If the lagging strand loops back, the entire replication complex can move in a single direction (E. coli)

Linking adjacent Okazaki fragments

Figure Genomes 3 (© Garland Science 2007) What if one side is faster?

Figure 15.22a Genomes 3 (© Garland Science 2007)

Figure 15.22b Genomes 3 (© Garland Science 2007)

Figure Genomes 3 (© Garland Science 2007)

The end game

Figure 15.24a Genomes 3 (© Garland Science 2007)

Figure 15.24b Genomes 3 (© Garland Science 2007)

Figure Genomes 3 (© Garland Science 2007)

Table 15.3 Genomes 3 (© Garland Science 2007)

Figure Genomes 3 (© Garland Science 2007)

Figure Genomes 3 (© Garland Science 2007)

Figure 15.33a Genomes 3 (© Garland Science 2007)

Figure 15.33b Genomes 3 (© Garland Science 2007)