BIO 205 Dr Raymond Viruses and Prions

Virus

small, obligate, intercellular parasite

nucleic acid and capsid

What are the 2 components of a virus

nucleic acid

viral genome of single or double stranded DNA or RNA

capsid

protein coat that surrounds and protects the viral nucleic acid

viral envelope

additional outer layer surrounding the capsid that only some animal viruses have

host cell membrane

what are viral envelopes made of

immune system does not recognize the virus as foreign

what is the advantage of a viral envelope

the spikes allow it to attach to and penetrate the host cell easier

what are the advantages of a virus with spikes

helical, polyhedral, complex

what are the 3 morphologies (shapes) of viruses

complex

Is this virus helical, polyhedral or complex

spiral

What shape are helical viruses

round

What shape are polyhedral viruses

the capsid

what determines the shape of a virus

viral replication

viruses copying themselves using the host cell machinery

block entry of the virus, block synthesis of nucleic acid, prevent assembly of progeny, prevent release of progeny

What are the ways antiviral drugs can inhibit viral replication

attachment, entry, synthesis, assembly, release

What are the stages of lytic viral replication

T4 bacteriophage binds to an E coli B receptor site

what happens in the attachment phase of lytic replication

T4 lysozyme enzyme weakens the membrane of E coli B and injects its nucleic acid into the E coli

what happens in the entry phase of lytic replication

T4 enzymes degrade E coli B DNA and use its host cell machinery to create nucleic acid and capsids

what happens in the synthesis phase of lytic replication

T4 nucleic acid is inserted into the capsules producing progeny

what happens in the assembly phase of lytic replication

lysozyme weakens the E coli cell envelope, the E coli lyses and viral progeny are released.

what happens in the release phase of lytic replication

attachment, entry, insertion, replication, induction, synthesis, assembly, release

what are the stages of lysogenic replication

Lambda bacteriophage binds to an E coli X receptor site

What happens in the attachment phase of lysogenic replication

Lambda lysozyme enzyme weakens the membrane of E coli X and injects its nucleic acid into the E coli

What happens in the entry phase of lysogenic replication

Lambda nucleic acid inserts itself into E coli x chromosomes and is replicated along with E coli X DNA

What happens in the insertion/replication phases of lysogenic replication

Lambda DNA is excised from E coli X chromosome

What happens in the induction phase of lysogenic replication

Lambda enzymes degrade E coli X DNA and use its host cell machinery to create nucleic acid and capsids

What happens in the synthesis phase of lysogenic replication

Lambda X nucleic acid is inserted into the capsules producing progeny

What happens in the assembly phase of lysogenic replication

lysozyme weakens the E coli X cell envelope, the E coli lyses and viral progeny are released.

What happens in the release phase of lysogenic replication

attachment, entry, synthesis, assembly and release

What are the stages of animal virus replication

animal virus binds to the host cell receptor

What happens in the attachment phase of animal virus replication

animal virus uses host cell machinery to make nucleic acid and capsids

What happens in the synthesis phase of animal virus replication

animal virus inserts nucleic acid into capsids to make progeny viruses

What happens in the assembly phase of animal virus replication

the virus exits the host cell via exocytosis grabbing a piece of host cell membrane on the way which becomes the viral envelope

What happens in the release phase of an enveloped animal virus

the virus bursts the host cell and exits via exocytosis

What happens in the release phase of a non enveloped animal virus

direct penetration, membrane fusion, endocytosis

what are the 3 methods in which viruses can enter animal cells

direct penentration

animal cell entry by which some non enveloped viruses bind to an animal cell receptor and inject their nucleic acid into the host cell (capsule remains outside)

membrane fusion

animal cell entry by which some enveloped viruses fuse their viral envelope with the animal host cell envelope and the entire virus (capsid and nucleic acid) enters the cell

endocytosis

animal cell entry by which some enveloped and non enveloped viruses bind to a receptor on the animal host cell and the entire virus (capsid and nucleic acid) is taken into the host cell

latency

The ability of a pathogenic virus to lie dormant within a cell

age, stress, weakened immune system, secondary infections, UV light exposure

what are examples of things that can cause reactivation of a latent virus

viruses insert their DNA into human DNA and alter the genes/proteins related to cell division.

how do viruses contribute to cancer

oncogene

Gene that can transform a normal cell into a cancer cell making it unable to control cell division

prion

proteinaceous infectious particle that goes to the brain and denatures its proteins

Mad cow, kuru, scrapie, fatal familial insomnia

what are some diseases caused by prions?

incinerate it to denature its protein

What is the only way to destroy a prion