Chapter 13 Vocab & Questions
Capsid/core
- A protein shell surrounding the genome. - Protects and introduces the genome into host cells. - Viruses that consist of only a genome surrounded by a capsid and are called nucleocapsid or naked viruses.
Which of the following descriptions fits a chronic viral infection?
Characterized by continuous production of low levels of viral particles, potentially even in the absence of active symptoms of disease. The organism is usually still highly infectious during this time.
Respiratory route of transmission
Flu, measles, colds
sexual route of transmission
Genital herpes
what is the function of the capsid/envelope?
Protects the nucleic acid when the virus is outside of the host cell Helps the virus bind to a cell surface and assists the penetration of the viral DNA or RNA into a suitable host cell
Which of the following descriptions fits the definition of a viroid?
Single-stranded RNA molecules forming a closed ring
SARS-CoV-2 is an enveloped, single-stranded positive-sense RNA virus. During infection, viral spikes attach to a host membrane protein called angiotensin-converting enzyme 2 (ACE2) that is found on cells in various organs, including the lungs, heart, intestines, and kidneys. Following attachment, the virus enters the host cell and begins replicating. Given this information, please select the TRUE statements about the virus and COVID-19. Check All That Apply
This is true. If the receptors to which SARS-CoV-2 are blocked, the virus cannot enter those cells.This is true. SARS-CoV-2 is an enveloped virus; the envelope is lipid and is easily destroyed by detergents etc.This is not true. SARS-CoV-2 is an enveloped virus; the envelope is lipid and is easily destroyed by detergents etc.
Please choose the statement that best describes the role of viral surface proteins or spikes.
Viral spikes provide means of attachment to host cell surface.
tumor
abnormal growth
Prions
are made of protein only
arboviruses
arthropod-borne viruses
Viral spikes
attach specifically to host cell receptors
lysogenic phage infections
attachment penetration incorporation/integration of virus genome into host genome virus genome multiplies host doesn't display virus genome
Lytic Phage Infection
attachment, genome entry, synthesis, assembly (maturation), Lysis ( release)
Every virus particle contains ______.
either DNA or RNA
Tobacco Mosaic Virus
first virus to be discovered
enveloped viruses enter by.....
fusion or endocytosis
shapes of capsid
icosahedral, helical, complex
lysogen
infected cell
prions
infectious proteins, mad cow disease
prohage
integrated phage DNA
What term describes the type of bacteriophage infection cycle where the bacteriophage DNA is inserted into the host cell DNA as a prophage and the infected bacteria can continue to grow and divide?
lysogenic
When present, what is the viral envelope composed?
mainly lipids
acellular
not composed of cells, considered non-living obligate intracellular
properties that distinguish acellular microbes from living:
-either DNA or RNA -unable to replicate on their own - do not divide by binary fission, mitosis, or meiosis -lack genes or enzymes neces. for energy prod. - they depend on ribosomes, enzymes, and metabolites of host cell for protein & nucleic acid prod.
virus families end in the suffix....
-viridae
Entry by endocytosis
1. Attachment: attachment to receptors triggers endocytosis 2. endocytosis: cytoplasmic membrane surrounds the virion, forming an endocytosis vesicle 3. release from vesicle: envelope of virion fuses with the endosomal membrane 4. Uncoating: Nucleic acid separates from capsid
Animal Virus Replication: Entry and Uncoating
1. Entire virion enters cell; 2. Uncoating: DNA/RNA separates from protein coat: 3. Replication of double stranded DNA viruses• transcribed to produce mRNA; • translated to make viral proteins 4. Replication of single stranded DNA viruses• Complement to DNA synthesized first 5. Replication of RNA Viruses: in cytoplasm• Require viral RNA-dependent RNA polymerase
Consider the plague assay shown below. What is the virus titer shown within the black box?
9
fecal-oral route of transmission
A method by which pathogens or parasites excreted in the fecal matter of an infected person are then indirectly ingested by an uninfected person. pollio
envelope of virus
An outer membrane surrounding the nucleocapsid that are derived directly from host cell membranes and are lipid bilayers
genome of viruses
DNA or RNA never both single or double stranded single or many, circular or linear carries genes to invade host cell.
The nucleocapsid is composed of
DNA or RNA, and protein.
capsomers
Each capsid is made of identical protein subunits called
persistent infections
continue for years or lifetime, may or may not have symptoms
Prion
No DNA or RNA made of proteins
virus
Nucleic acid: DNA or RNA has protective protein coat
chronic infections
continuous production of low levels of virus particles
entry by fusion with plasma membrane
attachment- spikes attach to host cell receptors membrane fusion- envelope fuses w cytoplasm mem. nucleocapsid released- into cytoplasm viral envelope remains part of cytoplasmic mem. uncoating- nucleic acid separates from capsid
matrix protein
between nucleocapsid and envelope
nucleocapsid
capsid and nucleic acid together
In virology, a plaque is a(n
clearing in a lawn of bacteria
Spikes on virus
projections that extend from the viral envelope that may aid in attachment to the host cell
Viral capsids are composed of ______.
protein
Viroid
single RNA no protective coat
viriods
single-stranged RNA molecules that have no surrounding capsids found in plants
in viral entry by endocytosis
the host cell's plasma membrane surrounds the whole virion and forms a vesicle
zoonotic viruses
transmitted from animal to human via animal vector
Almost immediately upon entry, the viral nucleic acid alters the gene expression of the host cell. t/f
true
Both enveloped and non-enveloped (naked) viruses can enter a cell by endocytosis. t/f
true
Removal of the capsid to release the virus nucleic acid into the host cytoplasm is called ______.
uncoating
plaque assays
used to quantitate phage particles in samples: sewage, seawater, soil zones of clearing = plaques
latent infections
viral genome (provirus) remains silent in host cell; can reactivate
virus genus suffix
virus
Naked virus
virus without an envelope
Rabies virus, which can be transmitted from animals to humans, is classified as a(n) ______ viru
zoonotic
acute infections
•Rapid onset; short duration •Burst of virions released from infected host cell •Immune system gradually eliminates virus