Viral Structure and Classification Overview

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Questions and Answers

What is the most abundant biological entity in aquatic environments?

Viruses

What is the most important mechanism of recycling carbon in the marine environment?

Viral infection of bacteria

What is the typical size of the smallest viruses?

~20 nm in diameter

Which virus has the largest genome size of any known viral genus?

Pandoravirus Signup and view all the answers

What surrounds the nucleic acid in a virus?

Protein coat (capsid) Signup and view all the answers

What percentage of the marine biomass do viruses kill each day?

Approximately 20% Signup and view all the answers

Which organism constitutes more than 90% of the biomass in the sea?

Viruses Signup and view all the answers

What type of virus do most viruses in aquatic environments belong to?

Bacteriophages (harmless to plant & animals) Signup and view all the answers

What is the typical size of human cells?

10-30 μm Signup and view all the answers

What is the primary composition of a Pandoravirus genome?

Double stranded DNA Signup and view all the answers

What is the mechanism of release for enveloped viruses?

Budding from plasma membrane Signup and view all the answers

How do bacteriophages infect bacteria?

Lytic Infection Signup and view all the answers

What is the genetic material of viroids?

Circular, ssRNA molecules Signup and view all the answers

What is the primary mechanism of replication for prions?

A type of protein that can trigger normal proteins in the brain to fold abnormally. Signup and view all the answers

What is the primary mode of replication for retroviruses?

+RNA reverse transcribed to produce the progeny viral DNA Signup and view all the answers

How does Hepatitis Delta virus differ from other viruses?

It is a defective virus Signup and view all the answers

What distinguishes prions from viruses?

They do not contain nucleic acids (Infectious proteins) Signup and view all the answers

How do naked viruses accumulate in the cytoplasm before release?

Released by burst of host cell Signup and view all the answers

What is the primary mode of release for bacteriophages?

Release by Burst Signup and view all the answers

How do retroviruses integrate their genetic material into the host cell?

Integration Signup and view all the answers

Which type of viruses include HIV and Influenza?

Enveloped viruses Signup and view all the answers

Where are the envelope proteins of viruses derived from?

Host cell's membrane Signup and view all the answers

Which classification system includes DNA and RNA viruses with specific enzymes and tropism for host tissues?

Baltimore classification Signup and view all the answers

Where do DNA viruses primarily replicate?

Nucleus Signup and view all the answers

What is the primary difference between enveloped and naked viruses?

Presence of a lipid envelope Signup and view all the answers

Which family of DNA viruses infects humans?

Herpesviridae Signup and view all the answers

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Study Notes

Overview of Viral Structure and Classification

Viruses are mostly found in marine environments and infect amoebae.
They can have DNA or RNA, single or double-stranded, and are enclosed in a protein coat, with some having a lipid envelope.
Viral capsids can have icosahedral or helical structures, and some viruses have complex structures.
Enveloped viruses include HIV and Influenza, while Poxviruses infect humans, Geminiviruses infect plants, and Bacteriophages infect bacteria.
Envelope proteins are derived from the host cell's membrane, while attachment proteins are embedded in the outer layer of the virus.
Viruses can be naked or enveloped, with genomes composed of DNA or RNA, varying in size and arrangement, and classified by ICTV and Baltimore classifications.
Baltimore classification of animal viruses includes DNA and RNA viruses, with specific enzymes and tropism for host tissues.
Human DNA viruses include Herpesviridae, Hepadnaviridae, Papillomaviridae, and Adenoviridae, while RNA viruses include Coronaviridae, Flaviviridae, and Picornaviridae.
Viral replication occurs in a host cell, with the virus using the host's energy and machinery and the ability to produce mRNA.
The viral replication cycle includes adsorption, penetration, uncoating, replication, assembly, maturation, and release from the cell.
Replication processes vary for different types of viruses, such as DNA viruses replicating in the nucleus and RNA viruses replicating in the cytoplasm.
Specific examples of viral replication processes include those of Adenoviridae, Herpesviridae, Coronaviridae, and Rhabdoviridae, among others.