Microbio/Imm 2500A – Bacteriology
Exam Study Guide
Prokaryotes - ANSWER -smallest, simplest and most abundance cells (5e30
cells)
-include Bacteria and Archaea
-lack a nucleus and complex organelles
Advantageous of Prokaryote Size - ANSWER -surface to volume ratio: larger
surface area for nutrient exchange, grow quicker by binary fission
-evolve quicker: haploid (one set) genome means a mutation has a drastic effect
Four phases of bacterial growth - ANSWER -Lag: cells adjust, begin to use
nutrients
-Logarithmic growth: exponential rate
-Stationary: capped by buildup of waste products and lack of resources
-Death: not enough nutrients
Generation Time - ANSWER Also known as doubling time, the time it takes for
one generation to occur (population doubles).
-can be fast (10 minutes) or slow (over 24 hours).
-a good pathogen does NOT need a fast doubling time.
Bacterial Classification: Shape - ANSWER -Coccus: circular, spherical shape
-Rod: stick, cylindrical shape
-Spirillum: worm, bent cylindrical shape
Bacterial Classification: Oxygen Ability - ANSWER -Obligate aerobe: requires
oxygen for growth
-Obligate anaerobes: oxygen is toxic for growth
-Facultative anaerobe: can use oxygen if present, but can also grow without
oxygen
-Aerotolerant anaerobe: doesn't use oxygen but oxygen is not toxic
-Microaerophile: grows best with low levels of oxygen
Taxonomy of Bacteria - ANSWER Genus and species not enough, use strain
-two strains of the same bacteria may only be 60% identical in terms of genome.
-same size and shape between species
Main Components of Bacteria - ANSWER -Cytoplasm
-Nucleoid: holds haploid genome, no membrane
-Ribosomes
,-Plasmid: extra-chromosomal elements, not required for growth, often encode
for fitness, transferrable
-Cytoplasmic membrane: part of cell envelope
-Cell wall: bacteria specific, part of cell envelope
Gram Stain
-process
-results - ANSWER Used to classify bacteria invented by Hans Christian Gram
-Process: stain with crystal purple, iodine solution used to absorb colour. Wash
with alcohol, counterstain with safranin (stains everything else pink).
-Results: the alcohol should wash the crystal purple out of gram negative
bacterium while gram positive retains purple colour.
-Mycoplasma bacterium without a cell wall must use acid fast staining.
Bacterial Cell Wall Properties - ANSWER Made out of peptidoglycan, rigid
structure and prevents osmotic lysis.
-held together by a glycol backbone (alternating G and M) held together by
glycosidic bonds and peptide cross-linkages.
Gram Positive vs. Gram Negative - ANSWER -Gram positive: 40 layers of
peptidoglycan
-Gram negative: more complex, two membranes with periplasmic space. Also
contains lipopolysaccharide (LPS).
Lipopolysaccharide (Endotoxin) composition - ANSWER Made up of:
-Lipid A: N-Acetylglucosamine disaccharide with fatty acid groups. Recognized
by the innate immune system leading to septic shock.
-Core polysaccharide
-O-specific polysaccharide (O-antigen): highly variable.
Primary Function of the Cytoplasmic Membrane - ANSWER -permeability barrier:
prevents leakage and function as a gateway for transport of nutrients
-protein anchor: transport, bioenergetics, and chemotaxis
-energy conservation: generation and use of protein motive force
Periplasm - ANSWER Only found in gram negative.
-found between the outer and inner membrane
-contains hydrolytic enzymes, proteins involved in transport
Virulence Factors - ANSWER Molecules produced by bacteria that cause
disease, encourage colonization and transmission.
-two categories: surface and secreted
Surface Virulence Factors - ANSWER -LPS, endotoxins
-Flagella: allow for mobility (chemotaxis), tumble and run
, -Pili (fimbriae): made of protein, involved in attachment to host cells, surfaces, or
other bacteria
-Capsules: made of exopolysaccharides, attaches to host cells for protection,
form biofilms
-Surface Proteins
-Secretion Systems
Endospores - ANSWER Highly differentiated cells formed within the parent cell
that are highly resistant to heat, harsh chemicals and radiation.
-'dormant' stage of the life cycle
-most common in soil, bacillus and clostridium.
Biofilms - ANSWER Problematic for joint replacements.
-Attachment to surface
-Micro-colony Development: begin to clump
-biofilm development: Exopolysaccahride (capsule) production
-Maturation into biofilm, dissolution releases planktonic forms
Secreted Virulence Factors (Exotoxins) - ANSWER -Hemolysins: blood cell killers
-Toxins that function within hosts: gain access into special cell types that disrupt
function
-Extracellular enzymes
-Superantigens: activate too many T cells
Intracellular Bacteria - ANSWER Are taken up and survive within the phagocytic
cells (e.g. macrophages)
-some force their own uptake into epithelial cells
-allows bacteria to hide from the immune system
The Black Death/ Plague
-hallmark symptoms - ANSWER -Incubation time of 2-6 days, symptoms 2-4 days
after
-Sudden onset of fever, chills ,headaches, muscle pain and weakness
-Painful swellings (buboes) of lymph nodes
-High fever, delirium (loss of mental function), mental deterioration, large black
pustules that burst, vomiting of blood, bleeding in lungs
Plague of Justinian/ First case of Bubonic Plague - ANSWER Named after
Eastern Roman Emperor Justinian, lead the Italian campaign. Killed 100 million.
-started in the 6th century
-caused by Yesinia Pestis
-Spread throughout Mediterranean, Italy and Europe.
-Continued in cycles for another 200 years until 750 AD.
Yersinia
-enterocolicia
Exam Study Guide
Prokaryotes - ANSWER -smallest, simplest and most abundance cells (5e30
cells)
-include Bacteria and Archaea
-lack a nucleus and complex organelles
Advantageous of Prokaryote Size - ANSWER -surface to volume ratio: larger
surface area for nutrient exchange, grow quicker by binary fission
-evolve quicker: haploid (one set) genome means a mutation has a drastic effect
Four phases of bacterial growth - ANSWER -Lag: cells adjust, begin to use
nutrients
-Logarithmic growth: exponential rate
-Stationary: capped by buildup of waste products and lack of resources
-Death: not enough nutrients
Generation Time - ANSWER Also known as doubling time, the time it takes for
one generation to occur (population doubles).
-can be fast (10 minutes) or slow (over 24 hours).
-a good pathogen does NOT need a fast doubling time.
Bacterial Classification: Shape - ANSWER -Coccus: circular, spherical shape
-Rod: stick, cylindrical shape
-Spirillum: worm, bent cylindrical shape
Bacterial Classification: Oxygen Ability - ANSWER -Obligate aerobe: requires
oxygen for growth
-Obligate anaerobes: oxygen is toxic for growth
-Facultative anaerobe: can use oxygen if present, but can also grow without
oxygen
-Aerotolerant anaerobe: doesn't use oxygen but oxygen is not toxic
-Microaerophile: grows best with low levels of oxygen
Taxonomy of Bacteria - ANSWER Genus and species not enough, use strain
-two strains of the same bacteria may only be 60% identical in terms of genome.
-same size and shape between species
Main Components of Bacteria - ANSWER -Cytoplasm
-Nucleoid: holds haploid genome, no membrane
-Ribosomes
,-Plasmid: extra-chromosomal elements, not required for growth, often encode
for fitness, transferrable
-Cytoplasmic membrane: part of cell envelope
-Cell wall: bacteria specific, part of cell envelope
Gram Stain
-process
-results - ANSWER Used to classify bacteria invented by Hans Christian Gram
-Process: stain with crystal purple, iodine solution used to absorb colour. Wash
with alcohol, counterstain with safranin (stains everything else pink).
-Results: the alcohol should wash the crystal purple out of gram negative
bacterium while gram positive retains purple colour.
-Mycoplasma bacterium without a cell wall must use acid fast staining.
Bacterial Cell Wall Properties - ANSWER Made out of peptidoglycan, rigid
structure and prevents osmotic lysis.
-held together by a glycol backbone (alternating G and M) held together by
glycosidic bonds and peptide cross-linkages.
Gram Positive vs. Gram Negative - ANSWER -Gram positive: 40 layers of
peptidoglycan
-Gram negative: more complex, two membranes with periplasmic space. Also
contains lipopolysaccharide (LPS).
Lipopolysaccharide (Endotoxin) composition - ANSWER Made up of:
-Lipid A: N-Acetylglucosamine disaccharide with fatty acid groups. Recognized
by the innate immune system leading to septic shock.
-Core polysaccharide
-O-specific polysaccharide (O-antigen): highly variable.
Primary Function of the Cytoplasmic Membrane - ANSWER -permeability barrier:
prevents leakage and function as a gateway for transport of nutrients
-protein anchor: transport, bioenergetics, and chemotaxis
-energy conservation: generation and use of protein motive force
Periplasm - ANSWER Only found in gram negative.
-found between the outer and inner membrane
-contains hydrolytic enzymes, proteins involved in transport
Virulence Factors - ANSWER Molecules produced by bacteria that cause
disease, encourage colonization and transmission.
-two categories: surface and secreted
Surface Virulence Factors - ANSWER -LPS, endotoxins
-Flagella: allow for mobility (chemotaxis), tumble and run
, -Pili (fimbriae): made of protein, involved in attachment to host cells, surfaces, or
other bacteria
-Capsules: made of exopolysaccharides, attaches to host cells for protection,
form biofilms
-Surface Proteins
-Secretion Systems
Endospores - ANSWER Highly differentiated cells formed within the parent cell
that are highly resistant to heat, harsh chemicals and radiation.
-'dormant' stage of the life cycle
-most common in soil, bacillus and clostridium.
Biofilms - ANSWER Problematic for joint replacements.
-Attachment to surface
-Micro-colony Development: begin to clump
-biofilm development: Exopolysaccahride (capsule) production
-Maturation into biofilm, dissolution releases planktonic forms
Secreted Virulence Factors (Exotoxins) - ANSWER -Hemolysins: blood cell killers
-Toxins that function within hosts: gain access into special cell types that disrupt
function
-Extracellular enzymes
-Superantigens: activate too many T cells
Intracellular Bacteria - ANSWER Are taken up and survive within the phagocytic
cells (e.g. macrophages)
-some force their own uptake into epithelial cells
-allows bacteria to hide from the immune system
The Black Death/ Plague
-hallmark symptoms - ANSWER -Incubation time of 2-6 days, symptoms 2-4 days
after
-Sudden onset of fever, chills ,headaches, muscle pain and weakness
-Painful swellings (buboes) of lymph nodes
-High fever, delirium (loss of mental function), mental deterioration, large black
pustules that burst, vomiting of blood, bleeding in lungs
Plague of Justinian/ First case of Bubonic Plague - ANSWER Named after
Eastern Roman Emperor Justinian, lead the Italian campaign. Killed 100 million.
-started in the 6th century
-caused by Yesinia Pestis
-Spread throughout Mediterranean, Italy and Europe.
-Continued in cycles for another 200 years until 750 AD.
Yersinia
-enterocolicia
