The plasma membrane and all of the surrounding layers external to it.

• Plasma membrane

• Cell wall

• Additional layers (capsule, slime layer)

• Cytoplasm

• Nucleoid

• External structures (pili, flagella)

(a)  

• Innermost membrane that encompasses the cytoplasm

• Selectively permeable barrier that acquires nutrients and eliminates waste

• Interacts with external environment.

(a)  

• Passive diffusion

• Facilitated diffusion

• Primary and secondary active transport

• Group translocation

(a)  

Rigid mesh-structure lying outside the plasma membrane

(a)  

Peptidoglycan strands have a (a)   shape, crosslinked for strength

• Well organized and not easily removed from cell

• Usually composed of polysaccharides

• Protective function (Resistant to phagocytosis, Protect from desiccation, Exclude viruses and detergents)

(a)  

• Similar to capsules except diffuse, unorganized, and easily removed

• May facilitate motility

(a)  

• Regularly structured self-assembling layers of protein or glycoprotein

• Protect from ion/pH fluctuations, osmotic stress, enzymes, predation, host defenses

• Maintains shape and rigidity

• Promotes adhesion to surfaces

(a)  

1 Membrane

(a)  

2 Membranes

(a)  

• Water (70%), Proteins

• Cytoskeleton-like system for organization

• Inclusion bodies/ gas vacuoles

• Ribosomes

• Nucleoid

• Plasmids

(a)  

Plasma membrane in-foldings

• Observed in many photosynthetic bacteria

• Observed in many bacteria with high respiratory activity

(a)  

• Aggregation of cell components

• Not bound by membranes but compartments for specific functions (protect cell from products, or specific conditions for a reaction)

• E.g. Carboxysomes—CO2 fixing bacteria

(a)  

• Involved in bacterial movement

• Provide buoyancy to aquatic bacteria

• Made of aggregates of hollow, cylindrical gas vesicles

(a)  

Sites of protein synthesis

(a)  

• Usually not membrane bound

• Usually 1 closed circular, ds DNA molecule/chromosome

• Supercoiling and proteins aid in folding and structure

(a)  

• Small, closed, circular, independent DNA molecules

• Carry genes that can confer a selective advantage in some situations

(a)  

• Short, thin, hair-like, protein appendages (1,000/cell)

• Can mediate attachment to surfaces, motility, and DNA uptake

(a)  

Longer, thicker, less numerous (10/cell)

• Required for conjugation

(a)  

Threadlike, locomotor appendages extending outward from plasma membrane and cell wall.

Functions:

• Motility

• Attachment to surfaces

• Virulence factors

(a)  

Moving parts, C-ring ring interact with stators and connects to rod

(a)  

”Stationary parts”, capture PMF through membran to generate torque, and drive rotation

(a)  

• Movement toward a chemical attractant or away from a chemical repellent

• Chemoreceptors transmit signals throughout the chemosensing system

(a)  

Flagellum rotates like a propeller.

• Very rapid rotation up to 1100 revolutions/sec.

• In general, CCW rotation = forward motion (run).

• In general, CW disrupts runs, = tumble.

• Coordinated by chemotaxis

(a)  

A Survival Strategy:

• Complex, dormant structure formed by some bacteria

• Form in response to nutrient depletion

• Is resistant to numerous environmental conditions:

• Heat, UV radiation, gamma radiation, chemical disinfectants, and desiccation

(a)