Questions and Answers
Viruses exhibit all the following except ______.
Host cells of viruses include ______.
Viruses ______.
Viral capsids are made from subunits called ______.
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Helical and icosahedral are terms used to describe the shape of a viral ______.
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A/an _____ is the protein shell around the nucleic acid core of a virus.
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One of the principal viral capsid shapes is a 20-sided figure with 12 evenly spaced corners referred to as a/an _____ capsid.
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A naked virus only has a/an ______.
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Which of the following is not a typical capsid shape?
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All of the following pertain to virus envelopes except ______.
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Viral spikes ______.
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The core of every virus particle always contains ______.
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Which of the following is not associated with every virus?
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Viral nucleic acid types include which of the following?
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Reverse transcriptase synthesizes ______.
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A negative RNA virus must first ______.
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Viruses with _____-sense RNA contain the correct message for translation, while viruses with _____-sense RNA must first be converted into a correct message.
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Classification of viruses into families involves determining all the following characteristics except ______.
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Which of the following represents a virus family name?
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Which of the following is not a viral order in the classification system?
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The correct sequence of events in viral multiplication is ______.
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Viruses acquire envelopes around their nucleocapsids during ______.
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In general, most DNA viruses multiply in the host cell's _____, while most RNA viruses multiply in the host cell's _____.
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Host range is limited by ______.
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Oncogenic viruses include all the following except ______.
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Which of the following is/are type(s) of cytopathic effects?
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The envelope of enveloped viruses ______.
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Viruses attach to their hosts via ______.
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Viral tissue specificities are called ______.
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The process of dissolving the envelope and capsid to release the viral nucleic acid is ______.
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Which of the following occurs during assembly?
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Mammalian viruses capable of starting tumors are ______.
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Persistent viruses that can reactivate periodically are ______.
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Which of the following is not a characteristic of a transformed cell?
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New, nonenveloped virus release occurs by ______.
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What structures are used by bacteriophages to attach to host cell receptors?
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Which of the following is incorrect about prophages?
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T-even phages ______.
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The event that occurs in bacteriophage multiplication that does not occur in animal virus replication is ______.
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Viruses that cause infection resulting in alternating periods of activity with symptoms and inactivity without symptoms are called ______.
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Uncoating of viral nucleic acid ______.
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In transduction, the viral genome ______.
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Lysogeny refers to ______.
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Viruses that infect bacteria are specifically called ______.
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During lysogeny, an inactive prophage state occurs when the viral DNA is inserted into the host ______.
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What type of phage enters an inactive prophage stage?
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The activation of a prophage is called ______.
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When a bacterium acquires a trait from its temperate phage, it is called ______.
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Which of the following will not support viral cultivation?
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Visible, clear, well-defined patches in a monolayer of virus-infected cells in a culture are called ______.
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When a virus enters a host cell, the viral genes redirect the genetic and metabolic activities of the host cell.
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Viruses are used to produce vaccines for prevention of certain viral infections.
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Viruses are considered ultramicroscopic because they range in size from 2 mm to 450 mm.
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Study Notes
General Characteristics of Viruses
- Viruses lack metabolism, meaning they cannot carry out metabolic processes on their own.
- Viruses possess genetic material (either DNA or RNA) and have a definite shape.
- They are ultramicroscopic, unable to be seen clearly with light microscopes.
Host Cells
- Viruses infect a variety of host cells, including humans, animals, plants, fungi, bacteria, protozoa, and algae.
Virus Structure
- Viral capsids, which protect the genetic material of viruses, are composed of subunits called capsomeres.
- Capsids can have different shapes, with helical and icosahedral being the principal types.
- Naked viruses consist only of a nucleocapsid, which is a protein shell around the nucleic acid.
Virus Envelopes and Spikes
- Viral envelopes are acquired from host cell membranes during the release process.
- Enveloped viruses have spikes that assist in the recognition and attachment to host cells.
Nucleic Acid in Viruses
- The core of every virus contains either DNA or RNA, but not both.
- Viral nucleic acid can be double-stranded DNA, single-stranded DNA, double-stranded RNA, or single-stranded RNA.
Virus Classification
- Viral families are classified based on characteristics such as type of nucleic acid, type of capsid, presence of an envelope, and number of nucleic acid strands.
- Example of a virus family: Herpesviridae, which includes various herpesviruses.
Viral Multiplication Cycle
- The sequence of viral multiplication involves adsorption, penetration, uncoating, synthesis, assembly, and release of new viral particles.
- Most DNA viruses replicate in the host's nucleus, while RNA viruses typically replicate in the cytoplasm.
Host Range and Tropisms
- The range of hosts that a virus can infect is influenced by the type of receptors present on the host cell membrane.
Oncogenic Viruses
- Some viruses can lead to tumor formation and are referred to as oncoviruses (e.g., Papillomavirus, Hepatitis B virus).
- Persistent viruses can reactivate, causing alternating periods of activity and inactivity.
Bacteriophages
- Bacteriophages specifically infect bacteria and may enter a lysogenic phase, where their DNA integrates into the bacterial chromosome.
Cytopathic Effects
- Viruses can cause visible changes in host cells known as cytopathic effects, which include inclusions and multinucleated giant cells.
Prophages and Lysogeny
- Prophages are inactive viral DNA integrated into the bacterial genome during lysogeny.
- Induction refers to the activation of a prophage, resulting in lytic infection.
Viral Cultivation
- Viruses can be cultivated using live lab animals, embryonated bird eggs, primary cell cultures, and continuous cell cultures.
Notable Insights
- The process of uncoating releases viral nucleic acids and occurs after viral penetration.
- Viruses are utilized in vaccine production to prevent certain viral infections.
- Viruses are considered ultramicroscopic due to their extraordinarily small size, typically ranging from 20 nm to 300 nm, contradicting the erroneous size range of 2 mm to 450 mm.
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Description
Test your knowledge of key concepts from Microbiology Chapter 6 with these flashcards. Explore the fascinating world of viruses, including their structure, host cells, and characteristics. Perfect for students looking to reinforce their learning and recall important information.
