The bacteriophage lambda genome can exist in either a linear form (see Figures 15.1 and 15.8) or a circular form. Diagram the resulting fragments as they would appear on an agarose gel after electrophoresis.

Key Concepts

Bacteriophage Lambda Genome Structure

The bacteriophage lambda genome can exist in two forms: linear and circular. The linear form is typically found during the lytic cycle, where the virus injects its DNA into a host cell, while the circular form is associated with the lysogenic cycle, where the viral DNA integrates into the host genome. Understanding these forms is crucial for predicting how the genome will behave during gel electrophoresis.

Gel Electrophoresis

Gel electrophoresis is a technique used to separate DNA fragments based on their size. When an electric current is applied, negatively charged DNA moves towards the positive electrode, with smaller fragments migrating faster than larger ones. This method allows visualization of the DNA fragments, which is essential for analyzing the results of the bacteriophage lambda genome's linear and circular forms.

Fragmentation Patterns

The fragmentation patterns of the bacteriophage lambda genome during electrophoresis depend on the form of the DNA and the restriction enzymes used. Linear DNA will produce distinct bands corresponding to the sizes of the fragments generated, while circular DNA may appear as a single band or multiple bands depending on its conformation and any cuts made. Recognizing these patterns is key to interpreting the results of the gel.