Chapter 13 Flashcards
Bacteriophage/phage
Virus that infects bacteria
Virion
Viral particle,nucleic acid surrounded by protein coat
Capsid
Protein coat surrounding nucleic acid of virion
Icosahedral
Virus appears round, actual triangular soccer ball
Helical
Cylindrival
Complex
Intricate structure, phages most common
Enteric
Fecal-oral
Respiratory
Respiratory or salivary route
Zoonotic
Vector ( bugs, mosquitos ) and animal to human direct
Sexually transmitted
Sexual contact
Lytic/virulent phages
Exit host at end of infection cycle by lysing cell. Forms new virus particles and called productive infections
Attachment
Phage attaches to specific receptors on cell wall
Genome entry
Tail contracts and phage DNA is injected, phage coat stays outside
Synthesis
Phage genome transcribed, phage proteins synthed, phage DNA replicated, virion components made, host DNA degraded
Assembly
Phage components assembled into mature virion
Release
Bacterial cell lyses, new infectious virions released
Burst Size
of phage particles released
Lytic Infection
Also called productive infections, release new virion particles during release phase by causing cell to lyse.
Lysogenic Infection
Phage incorporates own DNA into host cell genome
Temperate Phage
Directs a lytic infection or incorporates own DNA into host cell genome
Lysogenic infection
Phage incorporates own DNA into gen ome of host cell
Lysogen
Infected cell
Prophage
Incorporated Phage dna, can remain indefinitely or be excised by phage encoded enzyme
Lysogenic Conversion
Change in phenotype of lysogen as a consequence of specific prophage it carries
Filamenrous Phage
Cause productive infections but don’t kill host cells. Host cells grow more slowly.
Specialized Transduction 1
Temperate Phage injects DNA into bacterial host
Specialized Transduction 2
Phage DNA integrates into host cell DNA to become prophage
Specialized Transduction 3
Prophage excised from bacterial chromosome and mistake is made, some bacterial DNA is taken and piece of phage DNA left behind
Specialized Transduction 4
Replication/assembly produce defective phage particles that carry certain bacterial DNA instead of some phage dna
Specialized Transduction 5
DNA of defective phage injected into new host but can’t cause productive infection
Specialized Transduction 6
Bacterial DNA integrates into host genome via hologous recombination, can now be replicated with host DNA.
Restriction modification systems
Protect bacteria from phage infection by quickly degrading incoming foreign dna.
Restriction enzymes (many different types)
Recognizes short nucleotide sequences and cuts dna molecule at those specific sequences.
Modification enzymes (many types)
Protects host cell DNA from action if restriction enzymes by adding methyl groups to nucleobases recognized by restriction enzymes, making unrecognizable
Plaque assays
Used to quantitate phage particles in samples
Plaques
Circular zones of clearing
Reverse transcriptase
Synthesizes dna from rna template
Apoptosis
Programmed cell death
Acute infections
Sudden onset symptoms, short duration
Persistent infections
Can continue for years, up to life of host, with or w/o symptoms
Chronic infections
Continuous production of low levels of viral particles
Provirus
virus genome that is integrated into the DNA of a host cell
Cytopat ic effect
Distinct morphological alterations in infected cells
Inclusion body
Site of viral replication
Viroid
Single stranded rna molecule that varies in size and forms a closed ring, so far only infect plants
Prions
All protein, accumulate in neural tissue, essentially misfolded proteins. Infectious and non infectious.
