Bacteria

Bacterial Genome and Chomosome

→ generally circular

→ generally just one chromosome

→ haploid

→ chromosome is condensed through supercoiling

→ genes generally do not contain introns

→ generally, there is only one copy on any given gene

→ some genes are organized as operons. Many genes but one promoter. Single mRNA encodes for multiple proteins

infection

the successful colonization of the body by a microbe capable of causing damage to the body

virulence

the ability of a microbe to cause disease

virulence factor

a microbial product or strategy that contributes to the ability of the microbes to replicate and or survive in the host

pathogenesis

the development of a disease and the chain of events leading to that disease

India ink

→ most capsules are highly organized acidic polysaccharides coating the bacterial cell

→ produced by some gram-pos AND gram-neg

→ generally produced by bacteria associated with meningitis, pneumonia, or fulminant septic infection

Gram-positive cell wall

→ structure: thick (PAMP)

→ wall teichoic acid: polymers of glycerol phosphate or ribitol phosphate covalently attached to the cell wall

→ lipoteichoic acid (LTA) (PAMP): polymer of glycerol phosphate with a lipid anchor

→ cell wall proteins: exoenzymes

bacterial cell wall

function:

→ survival in an environment where the osmotic pressure is less than that of the cytoplasm

→ It’s NOT responsible for cell shape

outer membrane (unique to gram-negative eubacteria)

→ Outer leaflet: lipopolysaccharide

→ Inner leaflet: phospholipids

→ periplasm: contains enzymes for transport and hydrolysis

→ peptidoglycan layer (thin")

→ proteins: Porins (selective channels), Braun’s lipoprotein (present in inner leaflet, covalently attached to peptidoglycan)

endospore formers

resistant to:

→ extremes in temperatures, desiccation, UV, chemical disinfectants, alkaline pH

sporulation is triggered by nutrient limitation or other signals

spores germinate back to vegetative cells when growth conditions are favorable