Lecture 15 Flashcards
What differentiates the 4 classes of bacteria?
cell envelope
What is the main function of the cell wall?
define shape
What is unique about Mycoplasmas that sets them apart from the other types of bacteria? What does this uniqueness mean?
no peptidoglycan cell wall = less defined shape/morphology
What are characteristics of mycoplasmas?
super small, no peptidoglycan cell wall, has cytoplasm and cytoplasmic membrane, can grow on lab media (no need tissue culture)
What are mycoplasmas also called?
Ureaplasma
What compensates the integrity of the plasmic membrane due to no cell wall? How do mycoplasmas obtain stability?
use sterols (uptake from host cells) to make membrane more stable and less fluid
What is the morphology of mycoplasmas?
no morphology because of undefined shape
What type of appearance do mycoplasma colonies have?
“fried egg” type of look
What is the rate of mycoplasma growth?
slow: 2-4 weeks
What tracts/parts of the body do mycoplasmas usually infect?
respiratory and genitourinary
Which Mycoplasma species is most/best studied?
Mycoplasma pneumoniae
What diseases does Mycoplasma pneumoniae cause?
tracheobronchitis, encephalitis, pneumonia (TEP)
What are some characteristics of Mycoplasma pneumoniae?
respiratory mucosal surface bacterial pathogen ; could invade
What is the reservoir of Mycoplasma pneumoniae?
only humans
What are the virulence factors of Mycoplasma pneumoniae?
community-acquired respiratory distress syndrome (CARDS) toxin
What toxin does the CARDS toxin resemble as/closely related to?
pertussis toxin
What are methods to diagnose for Mycoplasma pneumoniae? (2)
PCR, antibody assays, chest x-rays
What are treatments against Mycoplasma pneumoniae?
erythromycin, tetracyclin, other antibiotics not targeting peptidoglycan
What are the antibiotics that target peptidoglycan cell wall?
vancomycin, bacitracin, cephalosporins, penicillin
Define viruses.
obligate intracellular parasites – use host cell machinery to replicate
What are viruses made up of?
nucelic acid core, protein capsid (nucleocapsid), (optional: envelope)
What is the delivery system of the virus?
what the virus needs to interact with host cell to enter it
What is the extracellular state and complete form of the virus?
virion
What are capsomers?
subunits of protein to form capsid
What shape can the viral genome be?
linear or circular
What are the 2 morphological shapes can the virus take the form of? (the 2 common ones)
icosahedral and helical
What kind of molecules do viruses synthesize in the host cell? (2 things)
proteins and nucleic acids — does not synthesize membrane
Why would viruses need to use a membrane envelope? (2 reasons)
used to enter cells and hide from the immune system
Why would an envelope virus not be able to infect a plant cell or a gram+ bacteria?
due to the plant cell wall
What organisms can enveloped viruses infect?
gram– or mycoplasma bacteria and mammalian cells
What criteria are used to classify viruses?
genomic makeup, morphological characteristics
What are the 3 stages of viral replication?
extracellular (attachment/entry), intracellular (synthesis of macromolecules needed for assembly), assembly and exit
How can we quantify the number of viral copies present in a cell or animal?
use viral titer to measure amount of virions
In the viral titer, which stage yields the highest titer?
release step
What are the 3 types of genes do viruses encode for?
early (immediate early), nucleic acid replication (early), late genes
What are the 3 types of infection?
acute, chronic, latent
What is the characteristic of an acute infection?
short period of time, short life cycle
What is the characteristic of a chronic infection?
goes for a long period of time, starts as acute, long lifecycle
What are the most common routes that viruses enter hosts?
respiratory, GI, transcutaneous, sexual
What is an exogenous virus?
comes from environment
What is an endogenous virus?
stays within the host for a long time, can get passed down, relates to latent infections
What is transcutaneous?
bite from animal
What are the common methods of spread and replication with viruses?
neurological system, bloodstream system, multiple pathways
What are the diagnostic tests used to detect viruses with viral disease?
PCR, ELISA, antigen assays, tissue culture
What are the 4 emerging viruses?
HIV, SARS, West Nile, Ebola
What is latent infection?
lysogenic viruses stay dormant within host cells, causing diseases every so often, not all the time
