Intro Flashcards
Antigenic change
Change surface antigens to avoid recognition by host
What happens in the presences of ds-RNA?
Interferons are induced due to the viral-infection in the cell, represented by ds-RNA
IFN alpha/beta
Inhibits viral protein synthesis, activate leukocytes to kill viruses
IFN gamma
Up regulates MHC I and II expression/antigen presentation, activate NK and Tc cells to kill virus-infected host cells. Only produced in immune system cells
Degenerate bacteria
Has missing structures that are typical to bacteria
What is the size of staph bacteria?
1 micron.
Moist heat sterilization
Kills vegetative cells and spores
Dry heat sterilization
Kills spores but may leave pyrogens
Filtration Sterilization
Great for micro organisms, but not viruses
Radiation sterilization
Germicidal UV, ionizing, DNA damage that blocks replication
Ethylene oxide gas
Sterilizing heat-sensitive materials, toxic alkylation agent
Phenol coefficient
Rating scheme for antibacterial agents, 5 means 5 times as effective as phenol
Transition mutation
Purine to purine
Transversion mutation
Purine to pyrimidine or vice versa
Genetic drift
Small DNA changes
Genetic shift
Large DNA change
Reassortment of DNA
Mixing of chromosomal elements from different strains
Homopolyploidy
Mixing between same strains
Heteropolyploidy
Mixing between different strains
Only RNA-viruses that can reassort
Bunyaviridae
Orthomyxoviridae
Arenaviridae
Reoviridae
Competent Cells
Can bind DNA, have DNA uptake, integrate DNA
Gram positive competent cells
S. pneumoniae
S. Aureus
Transformation
Taking in of new DNA into the cell’s DNA
Plasmid Transformation
DNA that can replicate itself that can incorporate new DNA into itself
Plasmids Toxins
ShigA-like toxin Botulinum toxin Cholera toxin Diphtheria toxin Erthrogenic toxin
Conjugation
Transfer of plasmids between cells via pilus. Need fertility genes. More in gram negative
Transduction
Requires a bacteria virus/phage. Virus takes the DNA to the new cell. DNA will become integrated if possible.
Recombination
Occurs in all bacteria and higher species. Requires a Holliday structure. (Picronaviridae is the only virus that can recombine)
Illegitimate recombination
Jumping genes/transposons to interrupt thee DNA
Complementation
2 copies of expressed genes in one cell
Phenotypic mixing
2 viruses in one cell that may produce daughter cells with qualities from both viruses
Diffusion Test
Used to determine antibiotic resistant bacteria
MIC
Minimum inhibitory concentration
Characteristics of viral genomes
Reproduce via assembly
Single or double stranded
Segmented or unsegmented
Characteristics of Bacterial Genomes
Reproduce via duplication>fission
Double stranded
Unsegmented
Viral Capsid Structure
Protein coat that is resistant to the environment. Subunits=pentamers and hexamers, are made of protomers. Envelope is between host and nucleocapsid. Spikes:glycoprotein projections thru the envelope
Viral Propagation: Adsorption
Requires interactionbetween unique viral surface proteins and highly specific host cell surface receptor
Viral Propagation: Penetration
Enveloped: fuse and release nucleocapsid into the cell
Naked virus: Nucleocapsid binds to membrane receptor sites, enters via vesicle
Viral Propagation: Uncoating
Always occurs in the cytoplasm of the host cell. Eclipse phase (when virus “disappears”)
