FIG 10.

Schematic model of thermally induced changes in the T7 bacteriophage. At room temperature (a) the capsid is slightly swollen because of the DNA pressure inside. The bulging of the capsid wall as shown in the scheme is not to scale. Upon heating to and incubation at a temperature of 65°C (b), the tail complex is broken off, resulting in the release of the genomic DNA. The capsid becomes more faceted due to the relaxation of the capsid pressure. Finally, at 80°C (c), the capsid becomes swollen and its surface irregular, and the capsids may become fragmented into large globular particles (this step is not shown).