1. General Bacteriology (Emily) Flashcards
What qualities of prokaryotes differ from eukaryotes?
Prokaryotes have:
-No nucleus
-No membrane-bound organelles
-Single coiled circular chromosome
-Extrachromosomal DNA (plasmid)
-Peptidoglycan in cell wall
-70S ribosome (30S & 50S)
-Coupled transcription/translation
What qualities of eukaryotes differ form prokaryotes?
Eukaryotes have:
-A nucleus
-Membrane-bound organelles
-Linear chromosomes
-No peptidoglycan in cell wall
-80S ribosome (40S & 60S)
-Not coupled transcription/translation
What are fungi?
Members of a group of eukaryotic organisms that includes microorganisms such as yeasts and molds, or a combo of both
What kind of environments can fungi grow in?
-Low temps (20-30C)
-Tolerant of high pressures and low pH
What is the difference in cell wall structure in fungi?
Composed of chitin
What is the difference in cell membrane structure in fungi?
Contains ergosterol as the primary sterol
What are common targets of antifungals?
Chitin and ergosterol
What constitutes a species of bacteria?
A collection of strains which have many properties in common and are clearly different from other strains
What are subspecies?
Species that are divided based on small phenotypic or genotypic differences
What are serovars/serotypes?
Antigenic properties
What are pathovars/pathotypes?
Pathogenic properties (virulence factors)
What are phage types?
Based on the ability to be lysed by specific bacteriophages
What are the 3 morphological forms of fungi?
-Mold
-Yeast
-Dimorphic
Mold: Mycelial growth at both ___________ and ______ temperature
Environmental; body
Yeast: Bacterial-like growth at both _________ and ______ temperature
Environmental; body
Dimorphic: Mycelial growth at ___________ temperatures and yeast growth at _______ temperatures
Environmental; body
What is a mycelium?
A mat of branching hyphae (vegetative form of fungus)
what is a hyphae?
Long, branching complex network of filaments that makes up mycelium
How can you differentiate species using hyphae?
Whether they’re septate or non-septate (septate are little divisions in the branches)
What 3 shapes do yeast come in?
-Oval budding
-Bottle shaped cells (oblong, footprint)
-Large, round encapsulated cells
How can you differentiate between fungal species?
Appearance of their colony, hyphal organization and the structure and organization of reproductive spores
Spores are _________ and germinate when conditions are favourable
Asexual
What are the 3 common morphological forms of bacteria?
-Coccus (little balls)
-Bacillus (rods)
-Spirochaete (swirly guys)
What bright field microscope settings are best for looking at bacteria?
Magnification of 1000x
What is diplococci?
2 cocci in a pair
What is streptococci?
Cocci arranged in chains
What are tetrads?
Cocci in a cube-like structure
What are sarcina?
Cubical packets of 8 cocci
What are staphylococci?
Cocci arranged in grape-like clusters
What are bacillus, diplobacilli, and streptobacilli?
Bacillus - Single rod-shaped bacterium
Diplobacilli - Bacilli arranged in pairs
Streptobacillus - Chains of bacilli
What are palasides?
Bacilli arranged in fence-like structure (kinda like a lightning bolt)
What is a coccobacillus?
Very short, rod-shaped bacteria (like an oval coin? idk)
What are 6 other shapes bacteria can come in? (idk if this is important but know it just in case i guess)
-Vibrio
-Spirillum
-Spirochete
-Filamentous
-Star-shaped
-Box-shaped
Why do bacteria have different shapes?
Primary selective pressures (nutrient acquisition, cell division and predation) and secondary selective pressures (mechanisms to combat primary pressures)
What colour do gram+ bacteria usually stain?
Blue or purple
What colour do gram- bacteria usually stain?
Pink or red
What do gram+ bacteria have that gram- bacteria dont?
A thick peptidoglycan cell wall (~90% of cell wall)
What do gram- bacteria have that gram+ bacteria dont have?
An outer membrane containing lipopolysaccharides (high lipid content)
What are 3 functions of the cell envelope?
-Protection
-Nutrient transportation
-Virulence
What are 3 functions of fimbriae/flagella?
-Motility
-Adhesion
-Conjugation
What are 5 important surface components?
-Protection
-Permeability barriers
-Adhesins
-Enzymes
-Sensing proteins
Why is the capsule of a bacteria important?
- Adherence - virulence, biofilm formation
- Protecting from phagocytosis
- Resistance to environmental stress (desiccation, antimicrobials)
What usually indicates the presence of capsules in a colony?
A slimy/mucoid appearance
What are the functions of a bacterial cell wall?
-Bacterial structure/shape and protection
-Target for antimicrobial drugs (B-lactams)
-Virulence factor
-Immunological distinction for strains
-Gram staining!!!
How does the outer membrane of gram-negative bacteria evade phagocytosis and the complement system?
It has a strong negative charge
What other two functions does the outer membrane of a gram-negative bacteria have that are important for its survival?
-Barrier to some antibiotics, digestive enzymes and chemicals
-Toxicity to mammalian cells due to the lipopolysaccharide component
Lipopolysaccharide (LPS) is made of O antigen, outer core, inner core, and lipid A. What is O antigen important for?
Immune response serotyping
Lipopolysaccharide (LPS) is made of O antigen, outer core, inner core, and lipid A. What is lipid A important for?
Uncontrolled activation of the immune system with production of inflammatory mediators —> Endotoxic shock!!
What are 4 characteristics of LPS?
-Endotoxin
-Heat stable
-Release when gram-negative bacterial cell wall ruptures
-Toxic to most animal cells
What is endotoxemia?
Presence of endotoxins in the blood
What is the difference in source between an endotoxin and an exotoxin?
Endo: Component of the cell wall of gram-negative bacteria released after death
Exo: Produced by live bacteria, primarily by gram-positive but can also be gram-negative
What is the difference in composition between an endotoxin and an exotoxin?
Endo: Lipid A of LPS
Exo: Protein
What is the difference in heat stability between an endotoxin and an exotoxin?
Endo: Heat stable
Exo: Most are heat labile
What is the difference in effect on host between an endotoxin and an exotoxin?
Endo: General systemic inflammation and fever
Exo: Specific damage to cells dependent on receptor-mediated targeting of cells and specific mechanism of action
What is lipoteichoic acid?
Its an exotoxin released from the cell membrane pf gram-positive bacteria and has similar effects to LPS
What are some qualities of the cytoplasmic membrane?
-Lipid bilayer with embedded proteins and is selectively permeable
-Site of respiration, secretion, photosynthesis
-Contains sensing proteins, enzymes, transport proteins
What is a flagella?
-Present in motile bacteria
-Long, filamentous structure
-Common in gram-negatives
What is a fimbriae/pili?
-Vary in number and type
-Thin, straight thread-like structures
-Used in adhesion and conjugation
-Common in gram-negatives
What is bacterial DNA composed of?
-Single chromosome (essential genetic info for survival)
-Plasmids (mobile genetic element and additional genes)
What organelle is the site of protein synthesis?
Ribosome
What is a common target of antimicrobials and why?
Bacterial ribosomes to inhibit protein synthesis. Differences between prokaryotic and eukaryotic ribosomes are why they’re good targets
What process contributes to horizontal gene transfer?
Recombination (exchange of DNA between bacteria)
What is transformation?
Uptake of a naked segment of DNA from a lysed “donor” bacterium
What is transduction?
Transfer of genetic information between bacteria and lysogenic phages
What is a bacteriophage (phage)?
Virus that specifically infects bacteria
What is conjugation?
Transfer of plasmids between bacteria
What occurs during conjugation in gram-negative bacteria?
A pilus will form and requires an F plasmid to transfer genetic material (F+ donor is female; F- recipient is male)
What are the 2 major genera of spore-forming bacteria?
Bacillus, Clostridium
What is the issue with spore-forming bacteria?
They are capable of surviving in harsh environments, but can be killed with UV radiation, ultra-high temperatures, and chemicals
What does the coat of a spore-forming bacteria do?
Protects against lytic enzymes
What does the cortex of a spore-forming bacteria have?
Peptidoglycan structure
The outer membrane of a spore-forming bacteria is ___________ to small molecules
Impermeable
What are the 4 permissive conditions for bacterial growth?
-Temperature
-pH
-Osmotic pressure
-Oxygen
What type of bacteria are usually most pathogenic to animals due to the temperature they thrive in?
Mesophiles (grow best in temps of 30-40C
If mammalian blood normally has a pH between 7.3-7.5, what type of bacteria will grow best?
Neutrophiles
All bacteria have a ________, _________, and __________ pH requirement
Minimum; maximum; optimal
Why are bacteria more tolerant of osmotic pressure than eukaryotic cells?
Because of their cell wall
Pathogenic bacteria usually grow best at osmotic pressures equivalent to __________ ________
Physiological saline (0.9% NaCl i think?)
What are oxygen metabolites?
Enzymes capable of reacting with oxygen
What is the enzyme that produces H2O2?
Super Oxide Dismutase (SODM)
What will peroxidase convert H2O2 into?
2 H2O
What will catalase convert H2O2 into?
2 H2O + O2
What are the 5 types of oxygen tolerance?
-Obligate aerobes
-Facultative anaerobes
-Microaerophilic
-Aerotolerant anaerobes
-Obligate anaerobes
Obligate aerobes
Require oxygen for aerobic respiration
Facultative anaerobes
Performs aerobic respiration when oxygen is available, but can perform anaerobic respiration
Microaerophilic
Require an oxygen concentration lower than atmospheric (2-10%)
Aerotolerant anaerobes
Performs anaerobic respiration but can survive in the presence of oxygen
Obligate anaerobes
Performs anaerobic respiration; inhibited or killed in the presence of oxygen
