The morphology of bacterial cells

 The morphology includes size and shape

Size of Bacteria

   Average bacteria 0.5 - 2.0 um in diam.

-Surface Area ~12 um^2

-Volume is ~4 um

-Surface Area to Volume is 3:1

-Typical Eukaryote Cell SA/Vol is 0.3:1

- Food enters through SA, quickly reaches all parts of bacteria

-Eukaroytes need structures & organelles

Shapes of Bacteria

- Coccus

*Chain = Streptoccus

* Cluster = Staphylococcus

- Bacillus

*Chain = Streptobacillus

-Coccobacillus

-Vibrio = curved

- Spirillum

- Spirochete

- Square

-Star

                       

 There is also the square bacterium      

                   

The bacterial components

• Flagella 

• Pili

•Capsule

• Plasma Membrane

• Cytoplasm

• Cell Wall

•Lipopolysaccharides

• eichoic Acids

• Inclusions

• Spores

Flagella

• Motility - movement

• Swarming occurs with some bacteria

– Spread across Petri Dish

–  Proteus species most evident

•  Arrangement basis for classification

– Monotrichous; 1 flagella

–  Lophotrichous; tuft at one end

– Amphitrichous; both ends

– Peritrichous; all around bacteria

•        Observe Picture in Micro Lab.

Pili

•  Short protein appendages

– smaller than flagella

•   Adhere bacteria to surfaces

–  E. coli has numerous types

•  K88, K99, F41, etc.

– Antibodies to will block adherence

•  F-pilus; used in conjugation

–  Exchange of genetic information

•  Flotation; increase boyancy

– Pellicle (scum on water)

– More oxygen on the surface

Capsule

• Glycocalyx - Polysaccharide on external surface

• Adhere bacteria to surface

–   S. mutants and enamel of teeth

•   Prevents Phagocytosis

–   Complement can’t penetrate sugars

Cytoplasm

•   80% Water {20% Salts-Proteins)

–   Osmotic Shock important

•  DNA is circular, Haploid

–   Advantages of 1N DNA over 2N DNA

–   More efficient; grows quicker

–   Mutations allow adaptation to the environment quicker

•  Plasmids; extra circular DNA

–  Antibiotic Resistance

• No organelles (Mitochondria, Golgi, etc.)

  

Cell Membrane

• Bilayer Phospholipid

• Water can penetrate

• Flexible

•  Not strong, ruptures easily

– Osmotic Pressure created by cytoplasm

Cell Wall

• Peptido-glycan Polymer (amino acids + sugars)

•  Unique to bacteria

• Sugars; NAG & NAM

– N-acetylglucosamine

–  N-acetymuramic acid

•  D form of Amino acids used not L form

–  Hard to break down D form

•  Amino acids cross link NAG & NAM

•  Determine shape of bacteria

• Strength prevents osmotic rupture

•20-40% of bacteria

• Unique to bacteria

• Some antibiotics effect directly

   -Penicillin

Teichoic Acids

•        Gram + only

•        Glycerol, Phosphates, & Ribitol

•        Attachment for Phages

Lipopolysaccharide (LPS)

•        Endotoxin or Pyrogen

–       Fever causing

–       Toxin nomenclature

•        Endo- part of bacteria

•        Exo- excreted into environment

•        Structure

–       Lipid A

–       Polysaccharide

•        O Antigen of E. coli, Salmonella

•        G- bacteria only

–       Alcohol/Acetone removes

Endospores

•        Resistant structure

–       Heat, irradiation, cold

–       Boiling >1 hr still viable

•        Takes time and energy to make spores

•        Location important in classification

–       Central, Subterminal, Terminal

•        Bacillus stearothermophilus -spores

–       Used for quality control of heat sterilization equipment

•        Bacillus anthracis - spores

–       Used in biological warfare

G+ vs. G-

•       G+

–       Thicker cell wall

–       Teichoic Acids

•       G-

–       Endotoxin - LPS