Unit 8: Viruses
This unit will introduce you to viruses. Viruses are in the grey zone between life and inorganic matter. You have learned that the cell is the smallest unit of life, because it can sustain all life functions including reproduction on its own. Most viruses are smaller than cells. They do not feed or reproduce on their own; instead, they hijack their host's metabolism when they multiply. All viruses are comprised of a nucleic acid core surrounded by a protein coat. Viruses are all categorized into seven groups based on the type of nucleic acid they carry. Viruses, while tiny, have powerful effects on their hosts; they can even cause cancer, birth defects, and death.
Completing this unit should take you approximately 21 hours.
Upon successful completion of this unit, you will be able to:
- describe how viruses are classified;
- diagram the process of viral replication;
- compare and contrast dsDNA, ssDNA, dsRNA, +ssRNA, and -ssRNA; and
- describe examples of each type of the above viruses and the diseases that result.
8.1: Virus Characteristics
Watch this lecture, which identifies the major characteristics of viruses.
Read this overview of DNA and RNA viruses, which are either single or double stranded and can vary in size and morphology.
8.2: Viral Replication Cycles
Read this chapter to learn about viral replication cycles.
8.3: dsDNA Viruses
8.3.1: Poxviruses
Study these slides. Note that poxviruses cause most diseases with the word "pox" in their names. The major exception is chickenpox, which is caused by herpesvirus, our next topic.
8.3.2: Herpesviruses, Adenoviruses, Papillomaviruses, and other Oncogenic Viruses
Read this chapter to learn about viruses that can cause cancer. Herpes viruses cause a variety of diseases, from genital herpes to mononucleosis to chickenpox. The human papillomavirus (HPV) has been associated with cervical cancer. A vaccination is now available for both females and males to prevent HPV infection. Take advantage of the PowerPoint lecture slides as you study.
8.4: ssDNA Viruses
8.4.1: Parvoviruses
Read this article to understand parvoviruses and their threat to our pets.
8.4.2: Geminiviruses
Read this article about the ssDNA viral family.
8.5: dsRNA Viruses
8.5.1: Arboviruses
Read this article on Arboviruses, which include the mosquito-spread West Nile Virus and Reoviridae. Reoviridae causes the gastroenteritis illness known as "Rotavirus."
8.5.2: Birnaviruses
Read the first three paragraphs of the introduction to gain an understanding of birnaviruses.
8.6: +ssRNA Viruses
8.6.1: Coronaviruses
Read this article to learn about Coronavirus and SARS. SARS, also known as severe acute respiratory syndrome, is caused by a type of coronavirus.
8.6.2: Picornaviruses
Read this article to learn about Picornaviruses, which cause intestinal problems as well as the common cold.
Read the article to learn about Rhinoviruses.
8.6.3: Caliciviruses
Read the section titled "Caliciviruses".
8.7: -ssRNA Viruses
8.7.1: Orthomyxoviruses
Read this chapter to learn about different types of flu viruses. Orthomyxoviruses are more commonly known as the flu virus. There are many kinds of flu viruses, including H1N1.
8.7.2: Paramyxoviruses
Read this chapter, which discusses Paramyxoviruses.
8.7.3: Rhabdoviruses
Read this chapter to further understand the dangers of rabies to animals and humans. One type of virus in the rhabdovirus family is called lyssavirus, which causes rabies. Rabies is infallibly lethal; if left untreated, it has a death rate of 100%.
8.7.4: Filoviruses
Read this article to learn about Filoviruses and hemorrhagic fever. Filoviruses cause viral hemorrhagic fevers, a particularly destructive set of conditions that often leads to death. One such virus is the Ebolavirus, which causes Ebola.
8.8: DNA and RNA Retroviruses
8.8.1: Hepadnaviruses
Read this chapter to learn about hepatitis. Retroviruses use intermediates to make copies of themselves. DNA retroviruses use RNA intermediates, while RNA viruses use DNA intermediates.
8.8.2: Lentiviruses
Read this article to learn about the HIV virus and AIDS. The most famous lentivirus is the human immunodeficiency virus, also known as HIV.
Read this page, and then click on the "Next" button on the bottom of the page. On the next page choose "What is alive?" This is a multiple-choice assessment. Choosing an option will bring you to a page that indicates whether you answered correctly or incorrectly and provides a short explanation. If you answer incorrectly, click on "try again" to repeat the question. If you answer correctly, click on the link to the next problem.
8.9: Antivirals
Read this chapter on anti-viral medications. Although the word "chemotherapy" is almost exclusively used in common language to refer to cancer treatment, it actually refers to the chemicals used in drug therapy for a variety of illnesses. Refer to Figure 1 on the attack mechanism of an enveloped virus as you study.