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