Ch 19: Viruses in Biology: Help and Review

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

A virus is defined as a microscopic and extremely infectious agent that invades and spreads, once inside a host. This lesson will dive into virology (the study of viruses), the history and structure of viruses, and how these infections exist in daily life.

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

Overview key descriptions of different viral shapes. Distinguish between the purposes of helical, icosahedral, prolate, enveloped, and complex shapes.

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

The life cycle of a virus includes several steps, including attachment, penetration, uncoating, replication, maturation, and release. Explore how viruses live, attack host cells, and replicate, and then learn the difference between lysogenic and lytic life cycles.

4. Classification of Viruses: Viral Genome and Replication Scheme

Viruses are classified according to their physical and chemical characteristics. Learn about factors involved in classification, including double- and single-stranded viruses, positive and negative sense, the Baltimore classification system, and reverse transcriptase.

5. Replication of DNA Viruses

Replication of DNA viruses occurs when a host cell's polymerase makes mRNA, which is sent back to the host cell's ribosomes. Discover replication strategies, DNA viruses' entry and integration, and the whole process of DNA replication and its release.

6. Replication of RNA Viruses

Ribonucleic acid (RNA) is a molecule found in cells that does many tasks for the human body, including the transformation of DNA information into proteins. Learn about RNA viruses and their replication strategies. Explore the features and viruses of RNA, such as double-stranded, positive and negative sense, and reverse transcription.

7. How Viruses Mutate: Antigenic Drift and Antigenic Shift

Viruses mutate and adapt to become more infectious. Explore the different ways viruses mutate, and learn about antigenic drive, antigenic shift, and viral recombination.

8. Viruses: Bacteriophage Lytic and Lysogenic Cycles

Viruses can infect many organisms, even bacteria. A bacteriophage is a special kind of virus that infects bacteria. Explore the way bacteriophages replicate using the lytic and lysogenic cycle.

9. Flu Viruses, HIV and Immune System Evasion

Some viruses, such as influenza and HIV, continue to spread and infect despite the human immune system. Understand characteristics of these viruses, such as rapid or high mutation rates, and how they help in evading the human body's protections.

10. Chicken Pox Virus Structure and Function

Chickenpox illness occurs due to the varicella zoster virus (VZV). Examine the structure and composition of this virus and how it infects cells, causing specific conditions such as shingles.

11. Epstein Barr Virus: Structure and Function

The Epstein Barr virus affects more individuals per year than you may know. If you catch it, it will make you very sick. We'll explore here what Epstein Barr is, what it does, and what it looks like.

12. Hepatitis C Virus: Structure and Function

Hepatitis C virus causes both short-term illness and chronic liver disease leading to cirrhosis and cancer. Learn about the virus and how it replicates.

13. Rabies Virus: Structure and Function

Rabies is a neurological disease spread by the saliva of infected animals. While it can be prevented by vaccination, it is deadly once symptoms appear. Learn more about this disease and the virus that causes it.

14. Rubella Virus: Structure and Function

The vaccines that children are given are meant to prevent their getting sick. One of the vaccines they get is the MMR shot, meant to prevent measles, mumps, and rubella. You may have heard of measles and mumps, but what is rubella? We discuss this further.

15. Smallpox Virus: Structure and Function

Smallpox is caused by a large virus that can go through several different stages to infect cells. This lesson will discuss the different forms of the virus and how they continue the smallpox infection from cell to cell.

16. Tobacco Mosaic Virus: Structure and Function

Tobacco mosaic virus is commonly found in tobacco plants, appearing in a 'mosaic' of discoloration patches. Learn the structure and function of this virus, including its effects on agriculture.

17. Variola Virus: Structure and Function

This lesson will discuss variola virus, the virus that causes smallpox. You will learn the functions of different parts of the virus structure, and how these parts work together to cause disease.

18. West Nile Virus: Structure and Function

The West Nile virus is an illness transmitted by mosquitoes. Individuals infected with this virus may be completely asymptomatic, or end up with extreme complications.

19. Yellow Fever Virus: Structure and Function

The yellow fever virus can be deadly and examining its structure and function is vital to obtain a better understanding of how it works. Investigate its genomes, proteins, and protective covering, discover the vectors of transmission and understand the symptoms.

20. Hepatitis A Virus: Structure and Function

This lesson will describe the structure and function of the virus that causes hepatitis A. After the lesson, there will be a few questions to test what you have learned.

21. Hepatitis B Virus: Structure and Function

Hepatitis B is part of a family of similar viruses that affect the liver. It can be deadly, but is often treatable, and for the past 30 years we've had a vaccine for it. This lesson will further explore the structure and function of the hepatitis B virus.

22. Herpes Simplex Virus: Structure and Function

Herpes is a virus that affects humans. It is one of the most common viruses to infect humans as it comes in a variety of different types. We look at the specific types of herpes simplex virus here.

23. Molluscum Contagiosum Virus: Symptoms & Treatment

Many diseases are found in human beings, and some are worse than others. A harmless virus, Molluscum contagiosum, is easily passed around and most often found in children. Read on to learn more about symptoms and treatment.