JACKLINE
First Aid USMLE STEP 1: Microbiology With Questions And 100% SURE ANSWERS
Terms in this set (571)
Cell Wall Overall Picture - Compare Gram (+) to
Gram (-)
Flagellum on bacteria is composed of what? Composition: Proteins
What is the function? Function: motility
Pilus/Fimbria on bacteria is composed of what? Composition: Glycoprotein
What is the function? Function: Mediate adherence of bacteria to cell surface, sex plus during conjugation.
Spore formation is ONLY possible is what type of Gram Positive Only
bacteria? Why is the formation of spores Function: Resistant to dehydration, heat, and chemicals.
important/beneficial?
What is the composition of a spore? Composition: Keratin-like coat; dipicolinic acid; peptidoglycan.
First Aid USMLE STEP 1: Microbiology
1/14
, 10/8/24, 11:28 AM
Function: Protects against phagocytosis
Capsule will be composed of what on bacteria?
What is the benefit of a capsule? Composition: Organized, discrete polysaccharide layer (except Bacillus anthracis, which
contains d-glutamate)
Function: Mediates adherance to surfaces, especially foreign surfaces (e.g., indwelling
catheters)
Glycocalyx
Composition:Loose network of polysaccharides
Space between the cytoplasmic membrane and outer membrane in gram-negative bacteria
(peptidoglycan in the middle)
Periplasm
Gram Neg only
Accumulates components exiting gram neg cells, including hydrolytic enzymes (β-lactamases)
Gram Neg Only
Function:
1. Endotoxin: Lipid A induces TNF and IL-1; O polysaccharide is antigenic
2. Most OMPs are antigenic
Porins: transport across outer membrane
Outer membrane (gram negatives)
Composition:
1. Outer Leaflet: endotoxin lipopolysaccharide [LPS/LOS]
2. Embedded proteins: porins and other outer membrane proteins (OMPs)
3. Inner Leaflet: phospholipids
Composition: Peptidoglycan is a sugar backbone with peptide chains cross-linked by
transpeptidase
Function: Net-like structure give rigid support, protects against osmotic pressure damage.
Cell wall and Gram Stain
Gram Stain:
Thick peptidoglycan layer retains crystal violet = gram +
Thin peptidoglycan layer turns red or pink with counterstain = gram -
Composition: Phospholipid bilayer sac with embedded proteins (PBP's) and other enzymes.
Lipoteichoic acids (gram Pos+ only) extend from membrane exterior.
Cytoplasmic Membrane
Function: Site of oxidative and transport enzymes
PBPs involved in cell wall synthesis
First Aid USMLE STEP 1: Lipoteichoic
Microbiology acids induce TNF and IL-1
2/14
First Aid USMLE STEP 1: Microbiology With Questions And 100% SURE ANSWERS
Terms in this set (571)
Cell Wall Overall Picture - Compare Gram (+) to
Gram (-)
Flagellum on bacteria is composed of what? Composition: Proteins
What is the function? Function: motility
Pilus/Fimbria on bacteria is composed of what? Composition: Glycoprotein
What is the function? Function: Mediate adherence of bacteria to cell surface, sex plus during conjugation.
Spore formation is ONLY possible is what type of Gram Positive Only
bacteria? Why is the formation of spores Function: Resistant to dehydration, heat, and chemicals.
important/beneficial?
What is the composition of a spore? Composition: Keratin-like coat; dipicolinic acid; peptidoglycan.
First Aid USMLE STEP 1: Microbiology
1/14
, 10/8/24, 11:28 AM
Function: Protects against phagocytosis
Capsule will be composed of what on bacteria?
What is the benefit of a capsule? Composition: Organized, discrete polysaccharide layer (except Bacillus anthracis, which
contains d-glutamate)
Function: Mediates adherance to surfaces, especially foreign surfaces (e.g., indwelling
catheters)
Glycocalyx
Composition:Loose network of polysaccharides
Space between the cytoplasmic membrane and outer membrane in gram-negative bacteria
(peptidoglycan in the middle)
Periplasm
Gram Neg only
Accumulates components exiting gram neg cells, including hydrolytic enzymes (β-lactamases)
Gram Neg Only
Function:
1. Endotoxin: Lipid A induces TNF and IL-1; O polysaccharide is antigenic
2. Most OMPs are antigenic
Porins: transport across outer membrane
Outer membrane (gram negatives)
Composition:
1. Outer Leaflet: endotoxin lipopolysaccharide [LPS/LOS]
2. Embedded proteins: porins and other outer membrane proteins (OMPs)
3. Inner Leaflet: phospholipids
Composition: Peptidoglycan is a sugar backbone with peptide chains cross-linked by
transpeptidase
Function: Net-like structure give rigid support, protects against osmotic pressure damage.
Cell wall and Gram Stain
Gram Stain:
Thick peptidoglycan layer retains crystal violet = gram +
Thin peptidoglycan layer turns red or pink with counterstain = gram -
Composition: Phospholipid bilayer sac with embedded proteins (PBP's) and other enzymes.
Lipoteichoic acids (gram Pos+ only) extend from membrane exterior.
Cytoplasmic Membrane
Function: Site of oxidative and transport enzymes
PBPs involved in cell wall synthesis
First Aid USMLE STEP 1: Lipoteichoic
Microbiology acids induce TNF and IL-1
2/14
