Bacterial Structure Flashcards
Peptidoglycan
Function and composition
Function: gives rigid support and protects against osmotic pressure
Composition: sugar backbone with peptide side chains linked by transpeptidase
Cell wall/cell membrane
Present in which kind of bacteria?
Function (1)
Composition (2)–which component induces TNF and Il-1
ONLY PRESENT IN GRAM +
Function: Major surface antigen
Composition: Peptidoglycan for support. Lipteichoic acid present which induces TNF and IL-1
Outer Membrane
Present in which kind of bacteria?
Function (2)
Composition (2)–which component induces TNF and Il-1 and which component is the antigen?
Only present in GRAM -
Site of endotoxin (LPS) and a major surface antigen
Composition: Lipid A induces TNF and IL-1. O polysaccharide is the antigen
Ribosome subunits:
50s and 30s
Periplasm
Function and composition
Space between the cytoplasmic membrane and outer membrane in GRAM NEGATIVE bacteria.
Composition: contains many hydrolytic enzymes including B-lactamases
Capsule
Function and composition
Protects against phagocytosis
Composed of polysaccharide
Spore
Function and composition
Resistant to dehydration, heat, and chemicals.
Composed of keratin-like coat; dipicolinic acid; peptidoglycan
Glycocalyx
Function and composition
Mediates adherences to surfaces, especially foreign surfaces (like an indwelling catheter).
Composed of polysaccharide
Bacteria with unusual cell walls/membranes (2)
Mycoplasma and mycobacteria
Mycoplasma cell membrane
Contains sterols and has no cell wall
Mycobacteria cell membrane
Contains mycolic acid. High lipid content
Gram stain limitations…these bugs (6) do not stain well
“These Microbes May Lack Real Color”
Treponema--too thin to be visualized Mycobacteria--high lipid content Mycoplasma--no cell wall Legionella--intracellular organism Rickettsia--intracellular Chlamydia--intracellular mostly
