Part 1:
50 min
Part 2:
50 min
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Part 1: Opening Activity – Introduce Viruses and Evolution
Time: 10 minutes
Introduce the topic of viruses and evolution by leading a class discussion. Remind students that viruses are pathogens, which are disease-‐causing agents. Ask students, What are some other kinds of pathogens? Students should recall that some bacteria, protozoans, and fungi are pathogens. Ask, What do these three kinds of pathogens have in common? Students should understand that all are living organisms and that each of these pathogens consists of at least one cell, the structural and functional unit of life.
Explain that viruses are not cells. Ask students, If viruses are not cells, are they alive? Encourage students to justify their opinions with examples of how viruses have some characteristics of life (e.g., a chemical composition based on organic macromolecules, genetic material, and the ability to evolve) but lack others (e.g., metabolism, growth and development, ability to self-‐reproduce, ability to respond to stimuli, and ability to maintain homeostasis).
Prompt students to recall the process of change over time, or evolution, that occurs in living things. Students may also identify this process as “natural selection.” Clarify that selection-‐-‐both artificial and natural-‐-‐is a mechanism that drives change in living things and that it works through interactions between the environment and the genetic material of living things. Students may wonder if something that is not
alive is capable of evolving. Assure them that viruses are indeed capably of evolving. As they learn more about the structure and behavior of viruses, they will see why.
Part 2: Opening Activity—Introduce Molecular Genetics and Viruses
Time: 5 minutes
Ask students to name the parts of a virus. Students may recall that viruses consist of a nucleic acid core surrounded by a protective protein coat. Ask students, What is an example of a nucleic acid? Students should recall that DNA and RNA are nucleic acids. Ask, How are nucleic acids important to organisms? Be sure students understand that the genetic material of life on Earth consists of nucleic acids.
Ask students to recall the roles of nucleic acids in cells and that changes in the nucleotide-‐base sequences of nucleic acids, called mutations, are common. Then ask, Why is it so hard to eradicate viral diseases? Why do think researchers have been unable to develop vaccines for significant viral diseases such as AIDS? Students should be able to relate a possible cause to the nature of nucleic acids and the processes of natural selection that lead to evolution. Explain that the way viruses adapt to and interact with their living hosts is an excellent example of evolutionary change.
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Part 1:
Part 2:
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View the full lesson plan here:
View the Answer Key to Student Recording Sheets here:
Overview and Purpose: The purpose of this lesson is to prepare students for exploring the biological basis of vaccines. Students will explore the nature of viruses, specifically their structure and ability to adapt through evolution. This lesson plan gives you a one-‐period class option (Part 1) and a two-‐period class option (Parts 1 and 2). Both options give students the chance to explore information and graphics that describe the nature of viruses and how they evolve. Additionally, Part 2 of the lesson plan includes modeling activities to engage students in a process of science and to enhance their understanding of complex concepts.
Learning Objectives
After completing Part 1 of this lesson, students will be able to:
- describe a virus as a nonliving pathogen that consists of a nucleic acid and a protective coat
- describe the protective coat of a virus as a capsid made up of protein molecules
- identify evolution as the outcome of change in the genetic makeup of organisms
- recognize the nucleic acid of a virus as either DNA or RNA
- recall that DNA is the genetic material in cells and that RNA assists with the process of protein synthesis
After completing Part 2 of this lesson, students will be able to:
- describe the ability of a nucleic acid to replicate and to undergo changes in its nucleotide-‐base sequence
- relate permanent changes in nucleic acids to mutations
- differentiate the mutability of an RNA virus from that of a DNA virus
- describe the structure of an RNA virus
- explain that some viruses develop a viral envelope made of host cell membrane as well as viral proteins and glycoproteins
- describe the reproductive cycles of influenza viruses that enable them to evolve through either antigenic shift or antigenic drift
This Lesson is sourced at:
The History of Vaccines Website, an award-winning informational and educational site created by The College of Physicians of Philadelphia.
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Part 1:
Part 2:
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Part 1: Closing Activity
Time: 10 minutes
Have groups of students (at least one for each source) summarize what they learned from their reading. Tell them they may use their recording sheets as a guide. Encourage other groups to add to or clarify information given about each of the readings.
Part 2: Closing Activity
Time: 10 minutes
Have each group of students report on what they learned, using their recording sheets as a guide.
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