General BacT and Mycology - Muller Flashcards
The phylogenetic tree of life contains 3 domains. Which are prokaryotes? Which are eukaryotes?
Prokaryotes: BacT + Archaea
Eukaryotes: Eukaryota (fungi, plants, animals, etc)
Where is genetic info contained in a prokaryotic cell?
In a single haploid circular chromosome
Regarding bacteria, why can nutrients easily and quickly reach all parts of the cell?
Bc bacT are small but have a large surface area to volume ratio
True or False: Not all bacteria have a capsule
TRUE
A bacterial capsule has a _________ outer layer
polysaccharide!!
A bacterial cell wall is made of a _____________ layer
Peptidoglycan layer
Does Gram + or Gram - have a thicker peptidoglycan layer?
Gram + has a thicker peptidoglycan (cell wall) layer
What is the purpose of gram staining?
Differentiates bacT by properties of their cell walls and by detecting peptidoglycan
What is the purpose of acid fast staining?
stains acid fast positive organisms due to mycolic acid in present in cell wall
What is an example of a bacteria you would use acid fast staining for?
Mycobacteria - mycolic acid in cell wall
What is the antigenic component of gram + bacteria?
Lipotechoic acid
Which is the antigenic component in Gram neg bacteria?
Lipopolysaccharides (LPS) (part of cell wall)
Specifically Lipid A - endotoxin
Does gram + or gram - contain the Lipid A?
Gram neg!
What is Lipid A?
Endotoxin in cell wall (LPS) of gram neg bacteria
activates immune system and exerts harmful effects
What is the virulence factor for mycobacteria?
Mycolic acid
What is endoflagella?
Flagella in the periplasmic space - only in Gram neg bacT!!!
Corkscrew like motility
Ex: Spirochetes have endoflagella
Explain the different types of pili/ fimbriae
Attachment pili: adherence to host
Conjugation pili: transfers genetic info
** pili also contributes to antigenicity (Ex: diarrhea in neonatal piglets)
Endospores are produced by which bacteria when exposed to nutrient depletion?
Clostridium + Bacillus
What are characteristics of endospores?
- Cryptobiotic state of dormancy
- Most durable cell in nature
- Survives a long time under extreme conditions
- Formed intracellularly
Which bacteria are exceptions to general bacterial properties and why?
- Mycoplasma: no cell wall
- Leptospira: 2 circular chromosomes
- Borrelia burgdorferi: linear chromosomes
Define the lag phase
increase in cell size, active metabolism of cells but NO DIVISION
Define exponential or logarithmic phase
cells multiply at max. rate
Define the maximal stationary phase
exhaustion of nutrients/ accumulation of toxins
balance between slow multiplication and cells dying
What nutrients are required for bacteria to grow?
Carbon and nitrogen
What is the bacterial sources of metabolic energy?
Fermentation
Respiration
Photosynthesis
What is a microaerophile?
Bacteria that requires a small amount of O2 to grow
_________ are bacteria that grow in 70-110 °C
Hyperthermophiles
Define exotoxins
proteinaceous toxins made by bacteria that exerts action on specific target cells when secreted or released following lysis
*** produced inside gram positive bacteria
Define endotoxins
cell wall components (LPS) that induce inflammation by stimulating immune system
** part of cell wall of gram neg bacteria
What are examples of biofilm?
Dental plaque
biofilm in catheters
UTI
Bacteria produce _________which allows cells to communicate
Autoinducers / pheromones
Explain quorum sensing
When bacterial population is HIGH autoinducers bind to receptors and promote group behavior (Ex: biofilm formation, virulence, conjugation, etc.)
When bacterial population is LOW autoinducers diffuse away from bacteria / no group behavior
______ + ________ help mediate transfer of genetic material
Capsules , fibriae/pili
All bacT contain peptidoglycan except ___________
Mycoplasma
________ is a harmful endotoxin in Gram negative bacT
Lipid A
What sequences of events are required to act as a pathogen?
- Must find appropriate host
- Must evade host
- Compete w normal microbiota to adhere to host tissues
- Multiply inside host
- Causes damage to host
True or False: Most bacteria are intracellular
FALSE MOST ARE EXTRACELLULAR
Give examples of obligate intracellular pathogens
- Rickettsia
- Chlamydia
Give examples of facultative intracellular pathogens
- Mycobacterium
- Rhodococcus
- Bartonella
Extrachromosomal DNA in bacteria is known as ________
Plasmids
How can bacteria transfer genetic material and virulence factors?
- Transformation (in the lab)
- Transduction (via bacteriophages)
- Conjugation (via plasmid)
What is pathogenesis?
mechanism that leads to a disease
What is pathogenicity?
ability of a microorganism to damage a host
What is virulence?
relative capacity of a pathogen to damage a host
