exam 3 part 4
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exam 3 part 4

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Questions and Answers

Which life cycle results in the host cell's death?

  • Replication cycle
  • Lytic cycle (correct)
  • Lysogenic cycle
  • Bacteriophage cycle

    • What happens to the prophage in the lysogenic cycle?

  • It integrates into the host chromosome. (correct)
  • It causes cell death.
  • It is expelled from the host cell.
  • It produces new virions immediately.

    • What type of viruses are known to infect bacteria?

  • Prokaryotic viruses
  • Eukaryotic viruses
  • Retroviruses
  • Bacteriophages (correct)

    • Which component of a virus aids in the attachment to host cells?

    <p>Tail fibers</p> Signup and view all the answers

    Which of the following correctly describes the biosynthesis phase of the lytic cycle?

    <p>Production of phage DNA and proteins</p> Signup and view all the answers

    What is a characteristic of virulent bacteriophages?

    <p>They always lead to the host cell's death.</p> Signup and view all the answers

    During which step of the lytic cycle does the phage inject its DNA into the host?

    <p>Penetration</p> Signup and view all the answers

    What are the basic components of a virus?

    <p>Capsid and Genome</p> Signup and view all the answers

    Which type of cycle can bring new genes to the host cell?

    <p>Lysogenic cycle</p> Signup and view all the answers

    What is the term for the assembly of viral particles during the lytic cycle?

    <p>Maturation</p> Signup and view all the answers

    What occurs during the lytic cycle of a phage?

    <p>The host cell lyses releasing new virions.</p> Signup and view all the answers

    What is the role of the lambda repressor protein in the lysogenic cycle?

    <p>It represses synthesis of other lambda-encoded proteins.</p> Signup and view all the answers

    Which type of transduction allows for any host gene to be picked up by a phage?

    <p>General transduction</p> Signup and view all the answers

    How does the SOS response affect the lambda phage?

    <p>It initiates the lytic pathway by removing the lambda repressor.</p> Signup and view all the answers

    What defines a temperate bacteriophage?

    <p>It can either lyse the bacteria or integrate its DNA into the host genome.</p> Signup and view all the answers

    During which phase is prophage DNA replicated?

    <p>Lysogenic phase</p> Signup and view all the answers

    Which of the following is NOT a characteristic of specialized transduction?

    <p>It can pick up any host gene without specificity.</p> Signup and view all the answers

    Which phage is known for being important in horizontal gene transfer?

    <p>Temperate phage</p> Signup and view all the answers

    What factor is essential for determining whether a temperate phage will undergo lytic or lysogenic pathways?

    <p>Genetic switch within the phage</p> Signup and view all the answers

    What happens to the host cell during the lytic cycle?

    <p>It eventually lyses and dies.</p> Signup and view all the answers

    Study Notes

    Bacteriophages

    • Bacteriophages are viruses that infect bacteria
    • Most bacteriophages infect Gram-negative bacteria
    • Two main types of bacteriophages:
      • Virulent bacteriophages: infect and destroy bacteria through lytic cycle
      • Temperate bacteriophages: integrate their DNA into bacterial genome through lysogenic cycle

    Lytic Cycle

    • Attachment: phage attaches to host cell
    • Penetration: phage penetrates host cell and injects its DNA
    • Biosynthesis: phage DNA and proteins are produced
    • Maturation: phage particles are assembled
    • Release: host cell lyses and releases new virions

    Lysogenic Cycle

    • Phage DNA is incorporated into host DNA as a prophage
    • Prophage is replicated along with host DNA
    • Viral repressor protein prevents expression of phage genes
    • Prophage can bring in new genes to host
    • Prophage may mutate and get stuck in the lysogenic cycle

    Temperate Bacteriophages

    • Can go through either lytic or lysogenic phase
    • Lytic phase: phage lyses bacteria
    • Lysogenic phase: phage integrates DNA into host genome

    Transduction

    • The transfer of bacterial genes from one bacterium to another by a bacteriophage
    • Two main types:
      • General transduction: any host gene can be picked up
      • Specialized transduction: phage can pick up adjacent genes during excision

    Induction of Lambda

    • Lambda phage is a temperate phage that can be induced to enter the lytic cycle by agents that damage DNA
    • Agents that damage DNA trigger the SOS response
    • SOS response: repair mechanism that removes the Lambda repressor
    • Removal of the repressor initiates the lytic pathway proteins leading to new virus production

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    Description

    This quiz explores the fascinating world of bacteriophages, highlighting their structure and the distinct lytic and lysogenic cycles they undergo. It covers the definitions, types, and processes of how these viruses interact with bacteria. Test your understanding of their roles in microbiology and their impact on bacterial evolution.

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