Textbook Question
All of the following can be transmitted by recreational (i.e., swimming) water sources except
a. Amebic dysentery.
b. Cholera.
c. Giardiasis.
d. Hepatitis B.
e. Salmonellosis.
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1. Introduction to Microbiology
Acellular Infectious Agents: Viruses, Viroids & Prions
2:09 minutesProblem 4
Textbook Question
A naked virus __________ .
a. Lacks a membranous envelope
b. Has injected its DNA or RNA into a host cell
c. Is devoid of capsomeres
d. Is one that is unattached to a host cell
Verified step by step guidance1
Understand the term 'naked virus' in virology: it refers to a virus that does not have an outer lipid membrane, also known as an envelope.
Recall that viruses can be classified as either enveloped or naked based on the presence or absence of this membranous envelope.
Recognize that the capsid, made of protein subunits called capsomeres, is always present in viruses, including naked viruses.
Analyze each option: (a) mentions lacking a membranous envelope, which aligns with the definition of a naked virus; (b) refers to the process of injecting genetic material, which is unrelated to the term 'naked'; (c) states the virus lacks capsomeres, which is incorrect because capsomeres form the capsid; (d) suggests the virus is unattached to a host cell, which is not a defining feature of naked viruses.
Conclude that the correct understanding of a naked virus is that it lacks a membranous envelope, corresponding to option (a).
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Video duration:
2mKey Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Structure of a Naked Virus
A naked virus is a virus that lacks a lipid membranous envelope surrounding its protein coat. It consists only of a nucleic acid genome enclosed within a protein capsid, making it more resistant to environmental conditions compared to enveloped viruses.
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Viral Capsid and Capsomeres
The capsid is the protein shell of a virus, composed of subunits called capsomeres. These capsomeres protect the viral genetic material and aid in attachment to host cells. Naked viruses always have capsomeres as part of their structure.
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Virus-Host Cell Interaction
Viruses infect host cells by attaching and injecting their genetic material, but a naked virus is defined by its structure, not by whether it has injected its DNA or RNA. Being unattached to a host cell does not define a naked virus.
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