Viral Replication: Lytic vs. Lysogenic Cycles

Biology Grades High School 5:11 Video
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Lesson Description

Explore the two primary methods viruses use to replicate: the lytic and lysogenic cycles. Understand how viruses hijack host cells to create copies of themselves and spread.

Video Resource

Viral replication: lytic vs lysogenic | Cells | MCAT | Khan Academy

khanacademymedicine

Duration: 5:11
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Key Concepts

  • Viral Structure and Entry
  • Lytic Cycle
  • Lysogenic Cycle
  • Provirus/Prophage
  • Repressor Genes

Learning Objectives

  • Students will be able to describe the basic structure of a virus and the different ways viruses enter host cells.
  • Students will be able to compare and contrast the lytic and lysogenic cycles of viral replication.
  • Students will be able to explain the role of repressor genes in the lysogenic cycle.
  • Students will be able to define provirus and prophage.

Educator Instructions

  • Introduction (5 mins)
    Briefly review the structure of viruses (proteins and nucleic acids) and introduce the concept of viral replication. Engage students by asking why viruses need to invade other cells to replicate.
  • Video Viewing (7 mins)
    Play the Khan Academy video on viral replication: lytic vs. lysogenic. Instruct students to take notes on the key differences between the two cycles and the methods of viral entry.
  • Discussion (10 mins)
    Facilitate a class discussion on the video. Use the discussion questions provided to guide the conversation and ensure students understand the core concepts.
  • Interactive Exercise: Cycle Diagram (15 mins)
    Have students work individually or in small groups to create diagrams illustrating the lytic and lysogenic cycles. Diagrams should include key steps, terms, and differences between the cycles.
  • Wrap-up and Assessment (8 mins)
    Review the key concepts and administer the multiple-choice and fill-in-the-blank quizzes to assess student understanding.

Interactive Exercises

  • Lytic vs. Lysogenic Cycle Diagram
    Students will create a visual representation (diagram, flowchart) of the lytic and lysogenic cycles, labeling all key steps and structures. This can be done on paper, digitally, or using modeling materials.

Discussion Questions

  • What are the three ways a virus can enter a host cell?
  • How does the lytic cycle differ from the lysogenic cycle?
  • What is a provirus/prophage, and in which cycle is it formed?
  • What is the role of repressor genes in the lysogenic cycle?
  • Under what conditions might a virus switch from the lysogenic to the lytic cycle?

Skills Developed

  • Critical Thinking
  • Scientific Communication
  • Visual Representation
  • Note Taking

Multiple Choice Questions

Question 1:

Which of the following is a key characteristic of the lytic cycle?

Correct Answer: Rapid replication and lysis of the host cell

Question 2:

In which cycle does the viral DNA integrate into the host cell's DNA?

Correct Answer: Lysogenic cycle

Question 3:

What are viruses made of?

Correct Answer: Proteins and nucleic acids

Question 4:

What is a provirus or prophage?

Correct Answer: A dormant virus integrated into the host's genome

Question 5:

What is the function of repressor genes in the lysogenic cycle?

Correct Answer: To prevent viral gene expression

Question 6:

Which of the following triggers the virus to switch from lysogenic to lytic cycle?

Correct Answer: Exposure to UV light

Question 7:

What happens to the host cell in the lytic cycle?

Correct Answer: It is lysed, releasing new viruses

Question 8:

What is the main goal of viruses during replication?

Correct Answer: To create as many copies of themselves as possible

Question 9:

Which viral entry method involves tricking the cell's receptors?

Correct Answer: Receptor binding

Question 10:

What type of genetic material can a virus have?

Correct Answer: Either DNA or RNA

Fill in the Blank Questions

Question 1:

The cycle in which the virus replicates and lyses the host cell is called the ______ cycle.

Correct Answer: lytic

Question 2:

In the lysogenic cycle, the viral DNA integrates into the host cell's DNA, forming a ______.

Correct Answer: provirus

Question 3:

__________ genes prevent viral gene expression in the lysogenic cycle.

Correct Answer: Repressor

Question 4:

The process of a virus breaking open a host cell is called ________.

Correct Answer: lysis

Question 5:

Viruses must invade a host cell to use its __________ and ATP to replicate.

Correct Answer: organelles

Question 6:

Bacteriophages enter bacterial cells by __________ their genetic material.

Correct Answer: injecting

Question 7:

If the host seems healthy, the virus will likely stay in the __________ cycle.

Correct Answer: lysogenic

Question 8:

The lysogenic cycle is a ___________ or latent phase.

Correct Answer: dormant

Question 9:

Viruses are made of proteins and one type of ___________ acid.

Correct Answer: nucleic

Question 10:

The viral proteins and genetic material __________-__________ to form fully functional viruses.

Correct Answer: self-assemble

Educational Standards

B.LS1.1:Construct an explanation based on evidence for how the structure of DNA determines the structure of proteins, which carry out the essential functions of life through systems of specialized cells. B.LS1.2:Develop and use a model to illustrate the hierarchical organization of interacting systems that provide specific functions within multicellular organisms. B.LS4.2:Construct an explanation based on evidence that biological diversity is influenced by (1) the potential for a species to increase in number, (2) the heritable genetic variation of individuals in a species due to mutation and sexual reproduction, (3) competition for limited resources, and (4) the proliferation of those organisms that are better able to survive and reproduce in the environment.

Teaching Materials

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