Chapter 13: Viruses, viroids, and prions

cytoplasm

DNA viruses and most RNA animal viruses replicate in the _________

budding

enveloped animal viruses are often released via _________ through the host cell membrane and allows the infected cell to remain alive for some time

uncoating

for a virus that penetrates a host cell with its capsid intact the capsid must first be removed in a process called _______

removed, nucleic acid

once a virus is inside a cell, the intracellular state is initiated, and the capside (and envelope, if there is one) is _______ and the virus will now exist solely as a ______ ______

ingestion, transplant, mucous

prions are transmitted by ______ of infected tissues, _______ of infected tissue, or contact with _______ membranes or breaks in the skin

generalists

some viruses are ________ meaning they can infect many kinds of cells in many different hosts

retroviruses

the +ssRNA viruses called _________ do not use their genome as mRNA and is converted to DNA by reverse transcriptase

release

the fifth step in lytic replication is _______ of the new virions from the host cell by lysing (bursting) the host cell

attachment

the first step in lytic replication is _________ of the virion to the host cell

assembly

the fourth step in lytic replication is _______ of new virions within the host cell

attachment

the function of a capsid is to allow ________ to host cells

enzymes

uncoating of a viral capsid happens using the host cells _________

genetic, attack, size, capsid, envelope

viruses are distinguished from each other by the types of _____ material they contain (DNA or RNA), kinds of cells they ______, ______ of virus, what the _____ coat is made of, shape of virus, and presence or absence of _______

acellular, growth, environment, reproduction

viruses are nonliving because they are _______, have no metabolism, no ______, no response to the ________ and no _______

DNA, RNA, cytoplasmic

viruses are very tiny, and made of genome which is either ____ or _____ (never both), they contain no ________ membrane, organelles or cytosol

cultures, chicken eggs

viruses can be cultured in host cells such as bacteria, plants, animals, cell _______ and embryonated ______ _______

genes, functional ribosomes

viruses cannot reproduce themselves because they lack the ______ for all the enzymes necessary for replication and do not possess ______ ________ for protein synthesis

capsid, envelope

when a virus is outside of a host cell they will contain structural components such as a ______ and an _______

bacteriophage

a virus that infects bacteria is a ______________

positive sense single stranded

A single stranded viral RNA that can act directly as mRNA is called _______ _____ ____ _____ RNA and occurs by making a complementary strand of RNA which is now a template for the genome

replication, release

a virus acquires an envelope from the host cell during viral ________ or _______

lytic cycle

In the _____ ______ the phage replicates and lyses the host cell to release new viruses which kills the host cell

burst time

____ _____ is the time from attachment of a virus to release (lytic replication)

prion prp

____ ______ causes normal PrP to become infectious

membrane fusion

______ _______ is for enveloped viruses where the envelope fuses with the membrane which allows entry of the capsid with the genome inside of it

direct penetration

______ ________ is when the capsid sinks into the membrane to create a pore for entry of its genome

lysogenic conversion

_______ ________ is a toxin encoded by viral genome which causes a bacterium to become pathogenic

prions

_______ are infectious proteins and lack nucleic acids

viroids

_______ are small circular pieces of RNA that have no capsid and only infect plants

dsDNA

_______ is most similar to host cell replication and occurs when the genome enters the nucleus of the host cell and is replicated using each strand of viral DNA as a template for its complement

latency

_______ is when a virus remains dormant (inactive) inside a host celll

induction

_______ is when the viral genome (DNA) is removed from the host chromosome which can be triggered by DNA damage

burst size

________ ______ is the number of virions released from a host cell

lysogenic replication

________ _________ is when the viral DNA is inserted into the bacterial chromosome, but virus remains inactive and the host cell is not lysed immediately allowing it to live

ssDNA

________ is a parvovirus and replicates by using the host cell's enzymes to synthesize a complement to DNA strand which forms a dsDNA

endocytosis

____________ is for mostly enveloped viruses and some naked viruses. They bind to a receptor on the host cell which triggers endocytosis of the entire virus (genome, capsid, and envelope)

virion

a _____ is a virus outside of the cell (in the extracellular state)

complex

a ______ viral shape has capsids of many different shapes (ex: bacteriophage)

polyhedral

a _______ viral shape is roughly spherical with a shape similar to a geodesic dome

naked

a _______ virus is a virion without an envelope

prophage

a ________ is an inactive bacteriophage which codes for a repressor protein to remain inactive

capsid

a ________ is made of protein coats composed of capsomeres

nucleocapsid

a _________ is a capsid and nucleic acid (genome)

helical

a _________ viral shape is capsomeres that spiral around the nucleic acid forming a tube like structure

exocytosis, lysis

a naked animal virus will be released by ________ and _____ of the cell, which is cell death

Prp

all mammals brain cells make a cytoplasmic membrane protein called ______

envelope

an ________ is a phospholipid membrane surrounding a capsid

enveloped

an ________ virus is a virion with an envelope

glycoprotein spikes

animal viruses attach to animal cells using ___________ _______ on the outside of the virus on the capsid or envelope which binds to receptors on host cell

permanent

in latency when a virus incorporates itself into the host chromosome this is _________

temporary

in latency when viruses do not incorporate themselves into a host chromosome this can be _______

negative sense single stranded

in order to synthesize a protein a cell's ribosome can use only mRNA (which is +ssRNA) and ribosomes don't recognize -ssRNA so for _____ _____ ______ _______ RNA the virus overcomes this problem by using the enzyme RNA-dependent RNA transcriptase

persistent infections

infections with enveloped viruses in which host cells shed viruses slowly and relatively steadily are called _______ ________

viral attachement

most viruses only infect specific types of cells due to the precise affinity of _____ ______ molecules (proteins or glycoproteins on the viral surface) for complementary proteins or glycoproteins on the surface of the host cell

alpha, beta

the normal functional structure of cellular PrP is arranged in ______ helices and the disease causing form (prion Prp) is arranged in ______ sheets

double stranded

the positive strand of ______ _______ RNA serves as mRNA for the translation of proteins and each strand of this molecule acts as a template for each other

viruses in cancer

the role of ______ ____ ______ lies around the activity of oncogenes or inactivation of oncogene repressors which can cause cancer to develop

entry

the second step in lytic replication is _______ of the virion or its genome into the host cell

synthesis

the third step in lytic replication is ________ of new nucleic acids and viral proteins by the host cell's enzymes and ribosomes

direct penetration, membrane fusion, endocytosis

the three ways that an animal virus can enter an animal cell are: _______ ______, _______ ______, and _______

viral DNA

the viral genome is incorporated into the host chromosome and the new host cells will now contain _____ _____

incinerate, sodium hydroxide

to destroy prions you must _________ it or autoclave in concentrated _______ _______