Podcast
Questions and Answers
What is the primary function of the viral envelope?
What is the primary function of the viral envelope?
Which of the following is NOT a primary shape of viruses?
Which of the following is NOT a primary shape of viruses?
What type of genetic material is found in retroviruses?
What type of genetic material is found in retroviruses?
Which of the following is a common method for viruses to gain entry into host cells?
Which of the following is a common method for viruses to gain entry into host cells?
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What is the primary basis for classifying viruses?
What is the primary basis for classifying viruses?
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What is the main difference between DNA and RNA viruses?
What is the main difference between DNA and RNA viruses?
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Which of the following is NOT a type of virus?
Which of the following is NOT a type of virus?
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What is the protective outer shell of a virus called?
What is the protective outer shell of a virus called?
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Which viral disease is NOT vaccine-preventable?
Which viral disease is NOT vaccine-preventable?
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What is the function of the nucleocapsid in a virus?
What is the function of the nucleocapsid in a virus?
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What is the purpose of a vaccine?
What is the purpose of a vaccine?
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Which part of a virus is made up of proteins acquired from the host cell?
Which part of a virus is made up of proteins acquired from the host cell?
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Study Notes
Viruses
Viruses are nonliving particles that can only replicate within host cells. They have a protective outer shell called a capsid, which protects their genetic material from being degraded by the environment. There are five main types of viruses: DNA viruses, RNA viruses, retroviruses, bacteriophages, and satellite virions.
Viral Diseases
Viral illnesses range from common colds and sore throats to more serious conditions such as hepatitis, shingles, meningitis, tuberculosis, rabies, Ebola virus disease, Marburg hemorrhagic fever, influenza, measles, HIV/AIDS, and SARS. Some viral diseases are vaccine-preventable, like polio and measles, while others require ongoing efforts to develop vaccines and treatments.
Vaccinations
Vaccination is one of the most effective ways to prevent infectious diseases worldwide. A vaccine introduces a small piece of the disease into your body so you can build immunity against it without actually getting sick.
Structure
The basic structure of a virus includes two main parts: the nucleocapsid—the core protein shell surrounding the viral genome; and the envelope, if the virus has one.
Nucleocapsid
The nucleocapsid is composed of protein subunits known as capsomeres. It surrounds the viral genome, protecting it and ensuring proper packaging.
Envelope
If the virus has an envelope, it's made up of proteins acquired from the cell membrane of the infected host cell during assembly. The envelope helps protect the virus from being recognized and destroyed by the host immune system.
Classification
Viruses are classified based on several factors, including their shape (morphology), size, type of genetic material they contain, and how they cause infection.
Shape and Size
There are three primary shapes of viruses: helical, enveloped, and icosahedral. These shapes vary greatly in their dimensions, with some measuring just 18 nanometers across and others over 300 nanometers.
Genetic Material
Viruses contain either DNA or RNA as their genetic material. DNA viruses typically have double-stranded DNA, while RNA viruses have single-stranded RNA. Infectious agents that contain both DNA and RNA are known as dual RNA-DNA viruses. Retroviruses, which use reverse transcriptase to convert their RNA genome to DNA, fall under this category.
Method of Entry
Viruses gain entry into cells through various mechanisms, such as fusion with the plasma membrane, endocytosis, and phagocytosis.
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Description
Explore the world of viruses, including their structure, classification based on genetic material and morphology, and the diseases they cause. Learn about how vaccinations play a crucial role in preventing viral illnesses.
