Lambda phage

Definition

Lambda phage is a type of bacteriophage that infects Escherichia coli (E. coli) and serves as a model organism for studying viral life cycles and genetics. It can undergo both lytic and lysogenic life cycles, showcasing the versatility of phages in their replication strategies and interactions with host cells.

5 Must Know Facts For Your Next Test

1. Lambda phage consists of double-stranded DNA and has a complex structure that includes a head, tail, and tail fibers that aid in attachment to E. coli.
2. In the lytic cycle, lambda phage can produce hundreds of new virions within a few hours before lysing the host cell.
3. During the lysogenic cycle, lambda phage's DNA can remain integrated in the bacterial genome for generations without harming the host.
4. The switch between the lytic and lysogenic cycles is influenced by environmental factors such as UV light or chemical stressors that can trigger the prophage to enter the lytic phase.
5. Lambda phage has been instrumental in molecular biology research, particularly in genetic engineering and recombinant DNA technology.

Review Questions

• How do lambda phage's lytic and lysogenic cycles compare in terms of their impact on the host cell?
  • The lytic cycle of lambda phage results in immediate destruction of the host cell as it bursts to release new virions. In contrast, during the lysogenic cycle, the viral DNA integrates into the host's genome and does not kill the cell immediately. This allows lambda phage to coexist with the host for extended periods, providing a means of survival until conditions favor entering the lytic cycle.
• Discuss the role of environmental factors in determining whether lambda phage enters its lytic or lysogenic cycle.
  • Environmental factors play a critical role in influencing lambda phage's life cycle decision. Conditions such as UV light exposure or chemical stresses can signal to the prophage that it is time to reactivate and enter the lytic cycle. This response allows lambda phage to adapt to changes in its environment, maximizing its chances of reproduction while also considering the viability of its host.
• Evaluate how lambda phage has contributed to advancements in genetic engineering and recombinant DNA technology.
  • Lambda phage has significantly advanced genetic engineering by providing tools for manipulating DNA. Its ability to integrate into bacterial genomes allows researchers to use it as a vector for cloning genes. This capability has led to breakthroughs in recombinant DNA technology, enabling scientists to insert foreign genes into bacteria for production of proteins or study gene function, ultimately impacting fields like medicine, agriculture, and biotechnology.

Related terms

Lytic Cycle: The lytic cycle is a viral replication process where the virus invades a host cell, replicates its genetic material, and ultimately causes the cell to burst, releasing new virus particles.

Lysogenic Cycle: The lysogenic cycle is a viral replication strategy where the viral DNA integrates into the host genome, remaining dormant until triggered to enter the lytic cycle.

Prophage: A prophage is the dormant form of a bacteriophage when its DNA is integrated into the host's chromosome during the lysogenic cycle.