EXAM I REVIEW - NYU Microbiology
Class of 24
Biofilms - answer Microorganisms that adheres to a surface (forks, rocks, teeth)
Extracellular polymeric substance (EPS) - answer Slimy and gluey matrix of polymers
What triggers biofilm formation - answer Environmental stress
Life cycle of biofilms - answer Attachment (adhesion) > Growth > Detachment
(dispersion).
Quorum sensing bacteria - answer Bacteria synchronously alter behavior in response to
population density and species composition
Antimicrobial resistance – answer EPS enclosure to escape antibiotics, slow growth
(antibiotics target fast growth), exchange of genetic materials, persister cells (cells that
escape effects without genetic change)
Biofilms in dentistry - answer Causes plaque, caries, pulpitis, periodontal diseases.
Control of biofilm in dentistry - answerphysical removal, antimicrobials, novel methods
such as EPS targeting enzymes, bacteriophage therapy.
Requirements of microbial growth - answer#1 is water
Elements (carbon, trace elements)
Organic materials (glucose, vitamins/coenzymes, amino acids)
Environmental factors influencing growth of microbes - answerTemperature
O2
pH
Osmotic pressure
Radiation/atmospheric pressure
Types of microbes and oxygen requirements - answerObligate aerobes (requires O2)
Facultative anaerobes (use O2 but can live without)
Obligate anaerobes (die in O2)
Endogenous nutrients provided by host saliva - answerAmino acids, peptides, proteins,
glycoproteins, vitamins, purines, pyrimidines
Exogenous nutrients provided by hosts' diet - answerFermentable carbohydrates,
, Sucross >>> glucans and fructans
Dairy,
Inorganic ions and trace elements
Prokaryotic reproduction - answerAsexually
Generation time (doubling time) - answertime it takes between successive binary
fissions or time it takes to double (Shorter doubling time means shorter incubation
period of disease).
Average 1-3 hours
E. coli = 20 mins
Phases of bacterial growth - answerlag, log, stationary, death
Use of specialized media - answerSelective media, differential media, enrichment
media, or a combination of selective and differential
Selective media - answerexploits a characteristic of one organism so that its' growth will
be favored.
Ex:
Low starting pH to select for only aciduric
Antibiotic containing media inhibits growth of others
Microscopic methods - answerBrightfield, darkfield, Phase contrast, electron
Bacterial stains - answerGenerally salts in which one of the ions are colored (methylene
blue = C16 H18 N3 S Cl * 3H2O)
Dissociates in water into positively charged methylene blue ion which is blue and
negatively charged chloride which is colorless
Dyes - answerBasic dyes = color portion is positive ion (methylene blue, crystal violet,
safranin)
Acidic dyes = color portion is in the negatively charged ion (nigrosin, congo red)
Direct/indirect staining - answerBacteria have a slight (-) charge so basic will stick, or
you can use acidic stain which will stain everything else
Gram staining - answer
Acid-fast stain - answerStains cells with glycolipids such as mycolic acid (stains red)
Class of 24
Biofilms - answer Microorganisms that adheres to a surface (forks, rocks, teeth)
Extracellular polymeric substance (EPS) - answer Slimy and gluey matrix of polymers
What triggers biofilm formation - answer Environmental stress
Life cycle of biofilms - answer Attachment (adhesion) > Growth > Detachment
(dispersion).
Quorum sensing bacteria - answer Bacteria synchronously alter behavior in response to
population density and species composition
Antimicrobial resistance – answer EPS enclosure to escape antibiotics, slow growth
(antibiotics target fast growth), exchange of genetic materials, persister cells (cells that
escape effects without genetic change)
Biofilms in dentistry - answer Causes plaque, caries, pulpitis, periodontal diseases.
Control of biofilm in dentistry - answerphysical removal, antimicrobials, novel methods
such as EPS targeting enzymes, bacteriophage therapy.
Requirements of microbial growth - answer#1 is water
Elements (carbon, trace elements)
Organic materials (glucose, vitamins/coenzymes, amino acids)
Environmental factors influencing growth of microbes - answerTemperature
O2
pH
Osmotic pressure
Radiation/atmospheric pressure
Types of microbes and oxygen requirements - answerObligate aerobes (requires O2)
Facultative anaerobes (use O2 but can live without)
Obligate anaerobes (die in O2)
Endogenous nutrients provided by host saliva - answerAmino acids, peptides, proteins,
glycoproteins, vitamins, purines, pyrimidines
Exogenous nutrients provided by hosts' diet - answerFermentable carbohydrates,
, Sucross >>> glucans and fructans
Dairy,
Inorganic ions and trace elements
Prokaryotic reproduction - answerAsexually
Generation time (doubling time) - answertime it takes between successive binary
fissions or time it takes to double (Shorter doubling time means shorter incubation
period of disease).
Average 1-3 hours
E. coli = 20 mins
Phases of bacterial growth - answerlag, log, stationary, death
Use of specialized media - answerSelective media, differential media, enrichment
media, or a combination of selective and differential
Selective media - answerexploits a characteristic of one organism so that its' growth will
be favored.
Ex:
Low starting pH to select for only aciduric
Antibiotic containing media inhibits growth of others
Microscopic methods - answerBrightfield, darkfield, Phase contrast, electron
Bacterial stains - answerGenerally salts in which one of the ions are colored (methylene
blue = C16 H18 N3 S Cl * 3H2O)
Dissociates in water into positively charged methylene blue ion which is blue and
negatively charged chloride which is colorless
Dyes - answerBasic dyes = color portion is positive ion (methylene blue, crystal violet,
safranin)
Acidic dyes = color portion is in the negatively charged ion (nigrosin, congo red)
Direct/indirect staining - answerBacteria have a slight (-) charge so basic will stick, or
you can use acidic stain which will stain everything else
Gram staining - answer
Acid-fast stain - answerStains cells with glycolipids such as mycolic acid (stains red)
