chapter 5 and 11 Flashcards
What type of parasites are viruses?
viruses are obligate intracellular parasites.
What is a key structural feature that all viruses contain?
Viruses contain a protein coat.
What do viruses lack that is essential for energy production?
Viruses lack an ATP-generating mechanism.
What determines the host range of a virus?
Host range is determined by specific host attachment sites and cellular factors.
What molecules do viruses contain instead of ribosomes?
Viruses contain DNA or RNA, but not ribosomes.
What are viral spikes used for?
spikes are used for attachment to host cells.
Do all viruses have an envelope?
No, only some viruses are enclosed by an envelope.
What structure do all viruses have
All viruses have a nucleocapsid.
What type of genetic material do viruses contain?
Viruses contain either DNA or RNA, but not both at the same time.
What is the shape of most viral nucleic acids?
Most viral nucleic acids are linear, although some are circular.
What makes up the protein coat of a virus?
The protein coat, called the capsid, is made of building blocks known as capsomeres.
What is the envelope of some viruses made of?
The envelope is made of a lipid bilayer.
What are spikes in viruses?
Spikes are embedded proteins on the virus surface.
What is the function of lysozyme in viruses?
Lysozyme helps bacteriophages make holes in the cell wall and lyse the bacterial cell upon exit.
What is the role of nucleic acid polymerases in viruses?
Nucleic acid polymerases are enzymes that assist in replicating the virus’s genetic material.
What is the function of neuraminidases in viruses?
Neuraminidases cleave glycosidic bonds and help release viruses from host cells.
how big is capsid of virus of t-even bacteriaphage
65 nm
What are the two main types of symmetrical virion morphology?
Icosahedral-Polyhedral and Filamentous-Helical.
What is the shape of a symmetrical icosahedral virus?
It is polyhedral, having 20 faces.
What is a filamentous-helical virion?
A virus with a long, thread-like structure that is coiled into a helical shape.
What is the morphology of an asymmetrical virion?
An asymmetrical virus has a complex structure.
What are the criteria used by the ICTV to classify viruses?
Genome composition, capsid symmetry, envelope, size of the virion, and host range.
What types of hosts are considered in virus classification by the ICTV?
Bacteria, Archaea, Animals, and Plants.
Which virus characteristic is used to classify viruses based on the shape of the protein coat?
Capsid symmetry.
What classification factor involves whether a virus has a lipid bilayer surrounding it?
Envelope.
What are the primary distinctions used in the Baltimore Classification of viruses?
Genome composition (RNA or DNA) and the viral replication strategy.
What does the Baltimore Classification system focus on regarding viral mRNA?
The route used to express messenger RNA (mRNA).
Who proposed the Baltimore Classification system?
David Baltimore in 1971.
What type of genome does Group I of the Baltimore Classification contain?
Double-stranded DNA.
What type of genome does Group II of the Baltimore Classification contain?
single-stranded DNA.
What type of genome does Group III of the Baltimore Classification contain
Double-stranded RNA.
What type of genome does Group IV of the Baltimore Classification contain?
(+) Single-stranded RNA.
What type of genome does Group V of the Baltimore Classification contain?
(–) Single-stranded RNA.
What type of genome does Group VI of the Baltimore Classification contain?
RNA retroviruses.
What type of genome does Group VII of the Baltimore Classification contain?
DNA pararetroviruses.
What do family names of viruses end in?
viridae.
What do genus names of viruses end in?
virus.
What defines a viral species?
A group of viruses sharing the same genetic information and ecological niche (host).
How are viral subspecies designated?
By a number.
What family does the Herpesvirus belong to?
Herpesviridae
What is the genus of the Herpesvirus?
Herpesvirus
What is the term used to refer to human herpesviruses?
Human Herpesvirus (HHV)
What are the types of Human Herpesvirus (HHV)?
HHV-1, HHV-2, HHV-3
What family does the Lentivirus belong to?
Retroviridae
What is the genus of the virus causing HIV?
Lentivirus
What viruses are part of the Human Immunodeficiency Virus (HIV)?
HIV-1, HIV-2
How must viruses be grown?
Viruses must be grown in living cells.
What is the result of growing bacteriophages in a lawn of bacteria?
Bacteriophages form plaques on a lawn of bacteria.
What are some methods used to grow animal viruses?
Living animals
Embryonated eggs
Cell culture
Continuous cell lines
What method involves growing viruses in fertilized eggs?
Embryonated eggs
What type of cell culture is often used for growing viruses?
continuous cell lines
What are the methods used for virus identification?
Cytopathic effects
Serological tests
Nucleic acids
What do serological tests detect in a patient?
Serological tests detect antibodies against viruses in a patient.
What is one way to identify viruses using antibodies?
Use antibodies to identify viruses in a patient.
What are examples of serological tests for virus identification?
Neutralization tests
Viral hemagglutination
Western blot
What does RFLP stand for and how is it used in virus identification?
RFLP stands for Restriction Fragment Length Polymorphisms. It is used to analyze viral DNA for identification.
What does PCR stand for, and how is it used in virus identification?
PCR stands for Polymerase Chain Reaction. It is used to amplify viral DNA or RNA for identification
What are the two main cycles of bacteriophage multiplication?
lytic cycle
Lysogenic cycle
What happens in the lytic cycle of a bacteriophage?
The phage causes lysis and death of the host cell.
What happens in the lysogenic cycle of a bacteriophage?
The prophage DNA is incorporated into the host’s DNA.
What is phage conversion?
phage conversion occurs when a bacteriophage changes the characteristics of the host cell, often by integrating new genes.
What is specialized transduction?
Specialized transduction is the process where a bacteriophage transfers specific genes from one bacterium to another by integrating into the host genome.
The Lytic Cycle: Virulent Mode
Attachment
Entry/Penetration
Biosynthesis
Assembly/Maturation
Release
Attachment:
phage attaches by tail fibers to
Entry/Penetration:
phage lysozyme opens cell
wall; tail sheath contracts to force tail core and
DNA into cell
Biosynthesis:
production of phage DNA and
proteins
Assembly/Maturation:
assembly of phage
particles
Release:
phage lysozyme breaks cell wall
What does burst size refer to in virus replication?
Burst size refers to the number of virions (new viral particles) released from a host cell after it has completed the replication cycle.
What is a permissive cell in the context of viral replication?
A host cell that supports the full replication cycle of a virus.
What are the three parts of the T4 genome?
Early and middle proteins
Late proteins
Phage DNA
What do early and middle proteins in T4 do?
They include enzymes for DNA replication and transcription.
What do late proteins in T4 do?
They form head/tail proteins and enzymes to release mature phage.
What is produced during infection by T4?
T4 nucleases, DNA polymerase, and new sigma factors.
What proteins are part of the T4 phage structure?
Phage head, tail, collar, base plate, and tail fiber proteins.
What does T4 lysozyme do?
It helps release mature phage particles by breaking down the host cell wall.
What types of mRNA are involved in T4 infection?
Early mRNA
Middle mRNA
Late mRNA
What occurs during T4 infection timeline?
Early proteins: Transcription/translation
Middle proteins: DNA replication
Late proteins: Self-assembly and lysis
