Temperate Phage

Definition

A temperate phage is a type of bacteriophage that can choose between two life cycles: the lytic cycle and the lysogenic cycle. This flexibility allows it to integrate its genetic material into the host bacterium's genome, becoming a prophage during the lysogenic phase, or to enter the lytic phase and immediately replicate and destroy the host. This dual capability is important for understanding how different viruses can impact their bacterial hosts and how they contribute to genetic diversity.

5 Must Know Facts For Your Next Test

1. Temperate phages can switch between lytic and lysogenic cycles based on environmental conditions, allowing them to adapt to their surroundings.
2. In the lysogenic cycle, the genetic material of the temperate phage can be passed on to daughter cells during bacterial replication, leading to genetic variation in bacterial populations.
3. Certain temperate phages can carry genes that confer beneficial traits to their bacterial hosts, such as antibiotic resistance or virulence factors.
4. The decision between entering the lytic or lysogenic cycle is often influenced by factors like nutrient availability and stress conditions faced by the host bacteria.
5. Temperate phages are significant in microbial ecology because they can influence bacterial population dynamics and gene transfer through horizontal gene transfer.

Review Questions

• Compare and contrast the lytic and lysogenic cycles in temperate phages and discuss how these cycles affect bacterial populations.
  • The lytic cycle involves rapid replication of the temperate phage, leading to cell lysis and release of new virions, which can rapidly decrease bacterial populations. In contrast, the lysogenic cycle allows the temperate phage to integrate its DNA into the host genome, remaining dormant while being replicated alongside bacterial DNA. This means that while lytic cycles may lead to immediate host cell death, lysogenic cycles allow for long-term persistence of viral genes within bacterial populations, contributing to genetic diversity and potential adaptations.
• Discuss how environmental factors influence whether a temperate phage will enter the lytic or lysogenic cycle.
  • Environmental factors such as nutrient availability, stress conditions like UV exposure or antibiotics can significantly influence a temperate phage's decision to enter either cycle. When conditions are favorable for bacterial growth, a temperate phage may opt for the lysogenic cycle, integrating its DNA into the host's genome. Conversely, under stressful conditions that threaten host survival, it may switch to the lytic cycle to maximize its replication before the host cell dies.
• Evaluate the role of temperate phages in horizontal gene transfer and their impact on bacterial evolution.
  • Temperate phages play a crucial role in horizontal gene transfer by facilitating genetic exchange between bacteria. When they enter the lysogenic cycle and integrate their DNA into a host's genome, they can carry additional genes that might confer beneficial traits like antibiotic resistance. This process not only allows for increased genetic diversity among bacterial populations but also accelerates evolution by enabling bacteria to acquire new functions more rapidly than through traditional mutation processes alone.

Related terms

Lytic Cycle: The lytic cycle is a viral replication process in which a virus invades a host cell, reproduces rapidly, and ultimately causes cell lysis, releasing new viral particles.

Lysogenic Cycle: The lysogenic cycle is a method of viral replication where the virus integrates its genetic material into the host's DNA, remaining dormant for an extended period before potentially entering the lytic cycle.

Prophage: A prophage is the dormant form of a temperate phage that has integrated its DNA into the host bacterium's genome during the lysogenic cycle.