Lytic and Lysogenic Cycles

Study Notes

Lytic Cycle

A viral reproductive cycle resulting in the death of the host cell.
Involves virulent phages, which reproduce solely through this cycle.

Stages of the Lytic Cycle

Attachment: Virus binds to a specific receptor on the host cell's surface.
Entry: Viral DNA is injected into the host, while the viral coat remains outside.
Replication: Host cell's metabolic functions are hijacked to produce viral components.
Assembly: New viral parts are assembled into complete virus particles.
Lysis and Release: Host cell bursts, releasing new viruses to infect adjacent cells.

Lysogenic Cycle

A viral reproductive cycle where the phage genome replicates without destroying the host cell.
Involves temperate phages capable of switching between lytic and lysogenic cycles.

Silent Phage Genome

When integrated into the host's chromosome, the viral DNA is termed a prophage.
A specific gene on the prophage produces a protein that inhibits transcription of other prophage genes, rendering the viral genome mostly inactive.

Trigger for Cycle Entry

The choice between lytic and lysogenic cycles is influenced by receptor interactions on the host cell membrane.
Environmental factors such as mutagens (e.g., radiation, certain chemicals) can trigger the transition to the lytic cycle by activating the viral genome to exit the bacterial chromosome.

Description

Explore the fascinating processes of viral reproduction through the lytic and lysogenic cycles. This quiz covers the stages of the lytic cycle and introduces the concept of temperate phages in the lysogenic cycle. Test your understanding of viral behaviors and their impact on host cells.