4: infection :cell surface structure

Flagellum?

Allow movement of bacteria

Rigid filament of protein that rotates

Straight shaped

Filament region is made of protein flagellin

flagellum structure learn

Describe movement of flagella

Flagella rotate

Movement differs:

• Peritrichous bacteria: swim in straight, steady paths.

• Polar or lophotrichous bacteria: move faster, spinning and darting rapidly.

Cell movement as a behavioral response:

Chemotaxis?

Directed movement of organisms in response to cheimcals

Fimbriae?

Enables organisms to stick to surfaces including human tissues

Made of proteins with adhesins at the tip

Example: salmonella typhimurium

Pili?

Allow conjugation- the transfer of genetic material between bacteria through cell to cell contact

Glycocalyx?

Provides protection for bacteria and allow bacteria to cling to surfaces

Function cell wall?

Allows cell to withstand internal pressure

GIves shape to cell

Peptidoglycan?

Tough mesh of polysaccharide (carb) and protein

Gives strength to bateria- only prokaryotes

Has a cross linked structure

Gram positive cell?

Gram negatuce cell?

Thick layer of peptidogylcan in cell wall

Thin layer of peptidogylcan

gram stain

Cell wall?

Site of action of antibiotics

Prevent bacteria from forming peptidogylcan

What extra layer do gram negative bacteria contain?

Outer membrane containing lipid bilayer

Forms a lipopolysaccharide layer

Main function outer membrane gram negative bacteria?

Toxicity

Give 2 functions cytoplasmic membrane

Permeability barrier

Protein anchor