Introduction Flashcards
<p>What is in a cell wall?</p>
<p>peptidoglycan</p>
<p>What is the cell membrane composed of?</p>
<p>LPS</p>
<p>What is the purpose of fimbrae and pilli</p>
<p>lead to cell attachment of other clels and sex pilli</p>
<p>What is the purpose of flagella?</p>
<p>Locomotion</p>
<p>What are serotypes?</p>
<p>Differentiated by the different cell surface structures</p>
<p>Carbon sources for bacteria?</p>
<p>Autotrophic (carbon fixation)
Heterotrophic (organic compounds)
Mixotorphic (auto and hetero)</p>
<p>Eenrgy sources for bacteria?</p>
<p>Chemotrophic (chemical)
| Phototrophic (light)</p>
<p>Sources of eletrons?</p>
<p>Lithotrophic (reducing equivalents from inorganic)
| Organotrophic (reducing equivalents from organic compounds)</p>
<p>What are terminal electorn accetors for cells?</p>
<p>Aerobic organisms ( oxygen as terminal electron acceptor)
| Fermentation (C as terminal electron acceptor)</p>
Explain the gram stain
Application of crystal violet , then iodine, alcohol to decolorize, then the application of safarin to countercolour
G+ purple
G- is pink
What are the serotypes of bacterial?
K- Capsule
O– LPS
F- Fimbrae
H- Flagella
Explain the hurdle concept
Deoptimizes a variety of factors at lower concentrations of each needed to inhibit bacterial growth. Can be additive or synergistic
What are some instrinstic factors?
pH Water Activity Nutrients Aerobic/anaerobic Microenvironments
What are some extrinsic factors?
Temperature
Packaging/Gaseeous environment
Differentiate G- and G+ bacteria
G+ THICK Cell wall TEichoic ACids G- Double membrane -Lipopolysaccharides
Explain bacterial growth curve
Lag phase- when bacteria are getting used to new envrionment
Exponential phase- exponential growth of bacteria in medium
Stationary phase- There is not enough nutrients for growth stalling
Death phase- due to lack of nutrients and space, they start to die off
What are some factors that influence bacterial growth
- Temperature
Most important, every 10C increase, the catalytic rate of enzyme doubles - Redox Potential (oxygen)
Potential energy difference, LEO GER
Aerobic, Anaerobic, facultative, Aerotolerant, microaerophillic
CAP, MAP, VP → types of packaging that controls air - pH
- Water Activity
What are some natural sources of pathogens and external sources of pathogens?
Natural Sources GI tracts Feathers Surface o cut fruits Damaged tissues Shells Skin Fur
External Sources of Pathogens Water Humans (workers Air Soil Sewage Equipment Packaging
Explain the different physiological states of bacteria
- Vegetative
Normal cells - Injured
Stressed- unable to grow on selective media (but can on non-selective)
tf appear dead, extended lag phase - Viable but not culturable
Do not grow on selective or non-selective media yet still cause problems - Biofilms
Cellular communciation/quroum sensing to create aggregations of cell (heterogeneous structures that are super resistant - Sporulated
Differentiated cells that are super resistant to heat and not easily destroyed
What is the difference between the the lytic and lysogenic phase?
THe Lytic pathway lead to replication of viral DNA and the bacterial cell lyses at the end of it
The lysogenic pathways lead to viral DNA being integrated into the host DNA and gets
What are the different mobile genetic elements?
Bacteriophage
Prophage: bacteriophage genomes inserted and integrated into circular bacterial DNA chromosome - carry genes for virulence factors or toxins required for pathogenesis
Lysogenic conversion- process prophage converts non pathogenic bacteria into a pathogen
Plasmids
Circular molecules of double standard DNA which self replicates
Pathogenicity island
Large DNA elements that are integrated in chromosome which genes the confer special properties on the bacteria that carry them
Transposons
DNA elements that hop from one place on the chromosome to another
What are the three categories of foodborne diseases?
Intoxication - ingestion due to growth of bacteria or mould
Infection- consumption of viable bacterial cells/viruses that multiply in GI
Toxicoinfection- illness due to large number of viable cells that die and release toxins
