Bacteria Cheat Sheet
Bacterial Cell Wall
There are three types of cell wall layers
o Gram positive
Stains purple with crystal violet
90% peptidoglycan
High muramic acid and low lipid content
Contains teichoic acid
Can form spores
o Gram negative
Stains pink with safranin
10% peptidoglycan
LPS-endotoxin
Doesn’t contain teichoic acid
High lipid content
o Acid fast
The function of the cell wall is to
o Maintain cell’s shape by countering osmotic pressure
o Protect bacteria from external stresses
o Provides attachment sites for bacteriophages
o Essential role in cell division
o Site of major antigenic determinants of cell surface
Gram Stain
To carry out a gram stain
o Set and stain bacteria with crystal violet
o Wash and Stain with iodine
o Wash and de-stain with ethanol
o Counterstain with Safranin
, Bacterial Cell Components
The cytoplasmic membrane
o Site of biosynthesis for DNA, cell wall polymers and membrane lipids
o Selective permeability and transport of solutes
o Electron transport and oxidative phosphorylation
o Excretion of hydrolytic enzymes
The capsule
o Contribution to virulence of bacteria preventing phagocytosis by white blood cells
The flagella
o Motility
Fimbriae
o Filamentous, adherence factor
o Can be gram positive or negative
Pili
o Long hair like projections that act as virus receptors for gram negative bacteria
Endospores
o Dormant and highly resistant
o Produced in times of stress
o Contain calcium dipicolinic acid
Plasmids
o Small DNA molecules that are circular or linear
o Self replicating and contain genes for AMR and virulence
Classification of Bacteria
Gram stains
Morphology
Metabolic behaviour
Growth temperatures
Biotyping
Infection patters
Antigenic composition
Bacterial Cell Wall
There are three types of cell wall layers
o Gram positive
Stains purple with crystal violet
90% peptidoglycan
High muramic acid and low lipid content
Contains teichoic acid
Can form spores
o Gram negative
Stains pink with safranin
10% peptidoglycan
LPS-endotoxin
Doesn’t contain teichoic acid
High lipid content
o Acid fast
The function of the cell wall is to
o Maintain cell’s shape by countering osmotic pressure
o Protect bacteria from external stresses
o Provides attachment sites for bacteriophages
o Essential role in cell division
o Site of major antigenic determinants of cell surface
Gram Stain
To carry out a gram stain
o Set and stain bacteria with crystal violet
o Wash and Stain with iodine
o Wash and de-stain with ethanol
o Counterstain with Safranin
, Bacterial Cell Components
The cytoplasmic membrane
o Site of biosynthesis for DNA, cell wall polymers and membrane lipids
o Selective permeability and transport of solutes
o Electron transport and oxidative phosphorylation
o Excretion of hydrolytic enzymes
The capsule
o Contribution to virulence of bacteria preventing phagocytosis by white blood cells
The flagella
o Motility
Fimbriae
o Filamentous, adherence factor
o Can be gram positive or negative
Pili
o Long hair like projections that act as virus receptors for gram negative bacteria
Endospores
o Dormant and highly resistant
o Produced in times of stress
o Contain calcium dipicolinic acid
Plasmids
o Small DNA molecules that are circular or linear
o Self replicating and contain genes for AMR and virulence
Classification of Bacteria
Gram stains
Morphology
Metabolic behaviour
Growth temperatures
Biotyping
Infection patters
Antigenic composition
