Bacteria: Structure, Growth and Taxonomy Flashcards
What are bacteria
Unicellular microorganisms; can be free living or host dependent
In Protista kingdom
Monera vs Protists
Monera:
Prokaryotes, Unpaired chromosome, no nucleus
Archaebacteria; Eubacteria
Protists: Eukaryotes, Paired chromosome, nuclear structure
Protozoa; Algae
What is bacterial cell wall made of
Peptidoglycan
Where is flagellum of bacteria anchored
Cytoplasmic membrane
Pili
Hair like protrusions on bacteria that allow for their adhesion and preventing them being flushed away
Also called fimbriae
Made of pilin protein
Where is energy produced in prokaryotes
In their inner membrane
Phenotypic Charactersitics to distinguish bacteria
Morphology
Biotyping - biochemical tests e.g. sugar fermentation rates/abilities
Antibiogram Patters
Genotypic Characteristics to distinguish bacteria
%G+C Ratios
DNA Hybridisation (see if specified probe binds to certain region)
Chromosomal DNA fragment analysis
Ribotyping (comparing ribosomal DNA genes of bacteria)
MALTI - TOF mass spectrometry (something laser something - time of flight); mass to charge ratio
Gram Stain
Differentiates bacteria on basis of their cell wall structure
First line test in diagnosis of bacterial infections
Can show shape and size of bacteria; may be definitive for particular bacterium genus
Allows empircal antibiotic treatment
What do gram positive and gram negative reactions indicate
Gram Positive - Thick Cell Wall
Gram Negative - Thin Cell Wall
How does gram staining work
Fix sample to slide
Stain everything in crystal violet dye
Flood sample with gram’s iodine which fixes crystal violet into peptidoglycan
Add decolouriser (alcohol/acetone) which removes violet from thin cell wall of gram - but not gram +
Flood with secondary dye to colour gram negative but gram + would stay violet
What is the gram reaction of E coli
Gram Negative Bacillus
Which type of gram bacteria is more susceptible to penicillin and lysozyme
Gram +ve more susceptible to penicillin; gram +ve is sensitive to lysozyme but -ve isnt at all