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Ch 4: Introduction to Viruses

About This Chapter

Watch microbiology video lessons, and find out about the different aspects of viruses. Learn how they are classified, how they form and how they replicate.

Introduction to Viruses - Chapter Summary and Learning Objectives

Chances are at some point in your life you have had a virus. Usually a virus is a total pain because antibiotics won't stop them. For example, if you have strep throat, caused by bacteria, you will be given an antibiotic that will clear up your symptoms pretty fast. However, if you get a virus, you will usually just have to suffer until it runs its course. Of course, there are many different viruses. You will learn about some of them in this chapter, like HIV, which can be treated with medications to some extent. Lessons will also cover the basics of viruses, like what they look like, how they duplicate and how they are classified. Some of the other things you will learn about include:

  • The discovery of viruses
  • Viral shapes
  • The viral lifecycle
  • Flu Viruses

VideoObjective
What Are Viruses? - Definition, Structure & Function Take a look at how viruses were discovered and the basic components of a virus.
Shapes of a Virus: Helical, Icosahedral, Prolate, Complex & Enveloped Find out about the different shapes viruses have, which help in their identification.
The Life Cycle of a Virus: How Viruses Live, Attack & Replicate Study the basics of how viruses live, attack and replicate.
Classification of Viruses: Viral Genome and Replication Scheme Learn about how viruses are classified.
Viruses: Bacteriophage Lytic and Lysogenic Cycles Examine the cycles of a virus.
Flu Viruses, HIV and Immune System Evasion Discover more about specific types of viruses and how they affect the human body.

9 Lessons in Chapter 4: Introduction to Viruses
What Are Viruses? - Definition, Structure & Function

1. What Are Viruses? - Definition, Structure & Function

In this lesson, you'll learn some historical facts about viruses and the material they are composed of. Find out more as we review the capsid, nucleic acids, the viral envelope, viruses, virions, bacteriophages and virology.

Shapes of a Virus: Helical, Icosahedral, Prolate, Complex & Enveloped

2. Shapes of a Virus: Helical, Icosahedral, Prolate, Complex & Enveloped

Learn about the different shapes viruses can have, such as helical, icosahedral, prolate, complex and enveloped. Find out why one shape is particularly useful from an energetic standpoint.

The Life Cycle of a Virus: How Viruses Live, Attack & Replicate

3. The Life Cycle of a Virus: How Viruses Live, Attack & Replicate

Find out how viruses infect and replicate as we explore the important steps of the virus life cycle, including attachment, uncoating, penetration, replication, and release, as well as the lysogenic and lytic cycles.

Classification of Viruses: Viral Genome and Replication Scheme

4. Classification of Viruses: Viral Genome and Replication Scheme

Find out how viruses are classified based on their being double-stranded, single-stranded, positive-sense, negative-sense, or by having something called reverse transcriptase.

Replication of DNA Viruses

5. Replication of DNA Viruses

This lesson will give you a basic overview of how DNA viruses replicate inside of a host cell. We will cover the entry, integration, replication and release of DNA viruses.

Replication of RNA Viruses

6. Replication of RNA Viruses

This lesson will give you a basic overview of how different types of RNA viruses replicate inside of an animal cell. We will cover the essence of being double-stranded and retroviruses, as well as positive-and negative-sense RNA viruses.

How Viruses Mutate: Antigenic Drift and Antigenic Shift

7. How Viruses Mutate: Antigenic Drift and Antigenic Shift

This lesson will discuss the major ways by which viruses, notably the flu virus, mutates. We will talk about recombination, reassortment, antigenic drift, antigenic shift, and more!

Viruses: Bacteriophage Lytic and Lysogenic Cycles

8. Viruses: Bacteriophage Lytic and Lysogenic Cycles

Viruses are generally not only our enemy but also the enemy of many other organisms. Bacteriophages are viruses that infect specific bacteria. In this lesson, we'll discuss their basic structure and infection cycle.

Flu Viruses, HIV and Immune System Evasion

9. Flu Viruses, HIV and Immune System Evasion

Why is it that our immune systems can protect us from some viruses but not others? We've eradicated smallpox by using vaccines, so why do influenza and HIV remain such dangerous health risks? In this lesson about viruses, we'll explore these questions and learn how influenza and HIV continue to evade the human immune system.

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