Usmle Step 1: Microbiology

Front 1

Function and chemical composition of bacterial structure: Peptidoglycan

Back 1

Function:
1. Rigid support
2. Protects against osmotic pressure

Chemical composition:
Sugar backbone with cross-linked peptide side chains

Front 2

Function and chemical composition of bacterial structure: Cell wall/cell membrane

Back 2

Gram positives only

Function: Major surface antigen

Chemical composition: Teichoic acid, which induces TNF and IL-1

Front 3

Function and chemical composition of bacterial structure: Outer membrane

Back 3

Gram negatives only

Function: Site of endotoxin (lipopolysaccharide) and major surface antigen

Chemical composition: Lipid A induces TNF and IL-1, and polysaccharide is the antigen

Front 4

Function and chemical composition of bacterial structure: Plasma membrane

Back 4

Function: Site of oxidative and transport enzymes

Chemical composition: Lipoprotein bilayer

Front 5

Function and chemical composition of bacterial structure: Ribosome

Back 5

Function: Protein synthesis

Chemical composition: 50S and 30S subunits

Front 6

Function and chemical composition of bacterial structure: Periplasm

Back 6

Function: Space between the cytoplasmic membrane and outer membrane in gram-negative bacteria

Chemical composition: Contains many hydrolytic enzymes, including beta-lactamases

Front 7

Function and chemical composition of bacterial structure: Capsule

Back 7

Function: Protects against phagocytosis

Chemical composition: Polysaccharide (except Bacillus anthracis which contains D-glutamate)

Front 8

Function and chemical composition of bacterial structure: Pilus/fimbria

Back 8

Function: Mediates adherence of bacteria to cell surface; sex pilus forms attachment between 2 bacteria during conjugation

Chemical composition: Glycoprotein

Front 9

Function and chemical composition of bacterial structure: Flagellum

Back 9

Function: Motility

Chemical composition: Protein

Front 10

Function and chemical composition of bacterial structure: Spore

Back 10

Function: Provides resistance to dehydration, heat, and chemicals

Chemical composition: Keratin-like coat and dipicolinic acid