Viruses medium

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Questions and Answers

What is the first step in the viral infection process?

Penetration of the host cell

Adsorption to specific receptors (correct)

Eclipse phase of viral replication

Release of new virions

Which method is NOT a way through which a virus can penetrate the host cell?

Direct fusion with the membrane

Intracellular transport through vesicles

Capsid disassembly outside the cell (correct)

Endocytosis

What factor is crucial for the Adsorption step of viral infection?

Availability of transcription factors

Viral genome characteristics

Presence of cellular receptors on the host cell (correct)

Virion maturity stage

What can influence the duration of the eclipse period during viral infection?

Time required for viral replication Signup and view all the answers

What is the role of cellular receptors in viral entry?

They enable the virus to attach and enter the cell. Signup and view all the answers

What is the primary role of the eclipse phase in viral replication?

To initiate the uncoating of the viral membrane Signup and view all the answers

Which of the following accurately describes translocation in viral infection?

The entry of non-enveloped viruses directly through the host membrane Signup and view all the answers

During which stage of viral replication does the synthesis of mRNA occur?

Transcription Signup and view all the answers

What are the two types of viral proteins synthesized during the replication process?

Structural and non-structural Signup and view all the answers

Where does viral assembly most commonly occur within a host cell?

In the nucleus, cytoplasm, or at the plasma membrane Signup and view all the answers

What is the outcome of lytic replication in viral infections?

The host cells die after releasing the virus Signup and view all the answers

What is the function of the mRNA synthesized during viral replication?

To code for the synthesis of enzymes for early replication Signup and view all the answers

What type of nucleic acid can viruses have?

Any combination of DNA or RNA, single or double-stranded Signup and view all the answers

Which statement accurately describes the mutation rates of RNA and DNA viruses?

RNA viruses usually display higher mutation rates than DNA viruses Signup and view all the answers

What is viral tropism?

The ability of a virus to infect specific types of cells or tissues Signup and view all the answers

Which of the following is NOT a feature of RNA viruses?

Stable compared to DNA Signup and view all the answers

Which virus is classified as a retrovirus?

HIV Signup and view all the answers

What is the primary characteristic that differentiates viruses from bacteria?

Viruses cannot reproduce independently. Signup and view all the answers

What component forms the protein shell of a virus?

Capsid Signup and view all the answers

Which of the following represents a method by which viruses replicate within a host?

Using host cell machinery Signup and view all the answers

What term describes the ability of a virus to infect a specific type of host cell?

Viral tropism Signup and view all the answers

Which type of virus contains a single-stranded RNA genome?

HIV Signup and view all the answers

What structural feature do prions lack compared to viruses?

Nucleic acids Signup and view all the answers

Which of these components consist of protein subunits arranged to form a structure in viruses?

Capsomeres Signup and view all the answers

Which of the following statements about viral persistence is accurate?

Viral persistence can occur without damaging the host's cells. Signup and view all the answers

How do some viruses acquire an external membrane envelope?

By budding off from the host cell Signup and view all the answers

Which is a feature associated with DNA viruses?

Double-stranded or single-stranded DNA Signup and view all the answers

Study Notes

Viral Entry and Replication

Viral entry depends on the presence of cellular receptors that permit viral entry.
Transcription factor availability influences viral replication.
Cellular receptors on the cell surface allow viruses to attach to the cell.
Viral replication and dissemination vary; some steps may be merged or omitted.
The eclipse period (time between infection and new virion production) can range from 3 hours to several months.

Stages of Viral Replication

Adsorption/Attachment: Virus particle attaches to specific host cell receptors. Firm attachment requires the presence of receptors on the host plasma membrane.
Penetration: Viral genome enters the host cell via endocytosis, fusion, or translocation.
Uncoating/Eclipse: A period where the virus is undetectable; the viral lipid membrane and protein capsid are removed, freeing the nucleic acid.
Transcription: mRNA is synthesized, coding for enzymes needed for viral replication; the virus utilizes host cell structures.
Synthesis of Viral Components: Viral proteins (structural and non-structural enzymes) are synthesized.
Assembly: Viral nucleic acid is incorporated into capsomeres, forming new virions. Assembly can occur in the nucleus, cytoplasm, or at the plasma membrane.
Release: Lytic replication results in host cell death and virus release; lysogenic replication allows the host cell to continue functioning.

Viral Structure and Classification

Viruses are smaller than bacteria and are obligate intracellular parasites.
Viral structure consists of a DNA or RNA genome inside a protein shell (capsid); some have an envelope.
Viruses vary in shape, genome type, and host range.
Viral genomes can be DNA or RNA, single-stranded or double-stranded. RNA viruses generally have higher mutation rates than DNA viruses. DNA viruses tend to be more stable than RNA viruses.
Capsid structure: Morphologically similar subunits (capsomeres) arrange precisely to create the capsid. Each capsomere is composed of protomers. Shapes include icosahedral, filamentous, and head-tail.

Viral Tropism and Persistence

Viral tropism refers to a virus's ability to infect specific cells, tissues, or host species. Some viruses have broad tropism.
Viral persistence involves the virus remaining in the host for extended periods, potentially with periods of both silent and productive infection.
Viral latency is the ability of a virus to remain dormant within a cell. This is distinct from chronic infection. Examples include HIV, Herpes, and Epstein-Barr virus.

Relevant Dental Viruses

The text notes that HIV, Hepatitis B, Varicella-Zoster, Herpes, and Influenza viruses will be covered in further detail. A table for completing information regarding various viruses and associated diseases is mentioned, but the table is not provided in the text.

Prions (briefly mentioned)

The text mentions prions but does not discuss them in detail.

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Description

Explore the crucial stages of viral entry and replication, focusing on the role of cellular receptors and the process of viral genome penetration. This quiz covers key concepts such as adsorption, uncoating, and the eclipse period, crucial for understanding viral behavior. Test your knowledge on the mechanisms that allow viruses to infect host cells.