Micro Ch.13

lysogenic conversion

a change in the phenotype of a lysogen as a consequence of the specifc prophage it carries.

two major categories of viral infectins

acute and persistent

assembly step in viral multiplication

also called the maturation step and is where capsids and genetic material are packaged into virions.

provirus

animal virus genome that has integrated into the host chromosome

in single stranded (-) Rna viruses the replicase uses (-) RNA

as a template to make (+) RNA which can be used for protein synthesis

Transducing particle

bacteriphage progeny that contains part of bacterial genome instead of phage DNA due to an error during packaging.

attachment

binding of a bacteriophage surface protein to a host cell receptor

In RNA viruses that have a single strand (+) RNA genome, the viral genome..

can be translated to make proteins and is used as a template to make complementary (-) RNA strands that act as templates to produce more (+) RNA strands.

temperate phage

can either cause a lytic infection or can incorporate its DNA into the host genome as a prophage.

filamentous phages

cause productive infections that do not kill the host cell.

enveloped viruses derive envelope from

certain host organelles and the host cytoplasmic membrane

which are persistent infections?

chronic infections and latent infections.

true or false enveloped and non-enveloped viruses all mature fully in the cytoplasm of the host cell.

false

true or false: most bacteria engulf bacteriophages as part of the pahge replication strategy.

false - bacteria are incapable of engulfment/phagocytosis

homologous recombination

following generalized transduction, DNa from the donor cell may be integrated into the recipient cell chromsome by homologous recombination.

+ strand

genome which serves as an mRNA

How viruses are classified?

genomic structure and host range.

The M13 phage has a single stranded DNA genome. Its replicative form is a double-stranded DNA molecule. The second strand of DNA is synthesized by..

host DNA polymerase

lysogeny

immunity to superinfection and lysogenic conversion

where do animal DNA viruses replicate in the host cell

in the nucleus

chronic

infection characterized by the continous, low-level production of new virus particles by animal host cells.

what does the host cell do with double stranded RNA

it carries its own replicase becasue the host cell cannot translate double stranded RNA.

What makes HIV special

it is both a persistent infection that continues with or without symptoms for years, or even the life span of the host. and is an acute infection with sudden onset of symptoms that are then cleared.

cold sore are caused by

latent HSV-1 that has reactivated and an initial infection with HSV-1

productive infection

new viral particles are produced.

enveloped and non-enveloped viruses entering the cell

non-enveloped only enter via endocytosis.

At a minimum, all viruses are composed of

nucleic acids and proteins

burst size

number of phage particles released from a host cell

nuclease

one of the early proteins expressed in the T4 lytic cycle is this enzyme that degrades the bacterial DNA.

what is associated with cancer

over 15 human papillomaviruses

Filamentous

phage type that causes productive infections that do not kill the host cell.

antigenic drift

phenomenon where the reassortment of gene segments that encode viral proteins that are recognized by the immune system can result in a loss of immune system's ability to recognize and respond to the virus.

lysis

physical rupture of a cell

phage induction

process by which phage DNA is excised from bacterial chromosomal DNA.

immunity to superinfection

protection of lysogens from infection by the same phage

processes needed for production of virus particles in a host cell

replication of viral genome, transcription of viral genes, and translation of viral genes

antigenic shift

result of when two different strains of a segmented virus enter the same cell, reassortment of the gene segments can occur

specialized transduction

results from an excision mistake made by a temperate phage during its transition from a lysogenic to a lytic cycle. produces defective phage particles. transfers phage DNA and adjacent host genes.

release

stage of viral multiplication at which budding occurs

uncoating

the process by which the viral nucleic acid is released from the protective protein coat

Replicase

the virally encoded polymerase needed for replication of RNA viruses. o

how does replication of double stranded DNA viruses

they follow the central dogma of molecular biology

spikes

things that stick out of viruses and help bind things.

how do viruses leave

triggering apoptosis and budding

generalized transduction

type of horizontal gene transfer that can occur when a phage carries a random piece of bacterial DNA; the phage acquires that DNA when a packaging error occurs during the assembly of phage particles in lytic cycle

retrovirus

uses reverse transcriptase to make a DNA copy from its RNA genome

latent state

viral genome remains silent within the cell.

before enveloped viruses bud from a host cell, specific viral proteins insert into the host membrane. these proteins become

viral spikes

which suffix represents a viral family

viridae

Which facts best support that viruses are nonliving

viruses are inert outside of a host and cannot reproduce on their own.

bacteriophages

viruses that infect bacteria are called phages or bacteriophages

operator

where the phage encoded repressor protein binds to on the incoming phage, preventing expression of the phage genes.

In enveloped viruses, what is between the nucleocapsid and envelope?

The matrix protein

Why are viruses challenging to study?

They are obligate intracellular parasites they require live organisms. Also they are too small to be seen via light microscope and need an electron microscope

why are arboviruses grouped together?

They are spread arthropods

True or False, Bacteriophages are important medically because they can be used to prevent the growth of food contaminating pathogens.

True

which suffix represents a viral genus.

-virus

Why is the study of viruses important?

-viruses can be a vehicle for horizontal gene transfer in bacteria -bacteriophages play a significant ecological role in reducing bacterial populations in nature - there are many medically important viruses that cause disease

Replication strategies of animal viruses are divided into 3 categories

DNA viruses, RNA viruses, and reverse transcribing viruses.

Viruses can contain both DNA and RNA. T or F

F they cannot.

extrusion

M13 particles are assembled during a process which the viruses uses to exit the cell.

why do RNA viruses have a higher mutation rate?

RNA viruses lack proofreading ability

Which of the following proteins is essential for maintenance of the lysogenic state?

Repressor

in the lytic cycle what does lysozyme degrade?

The cell wall