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Home , Cell membrane, Endospore, Flagellum, Glycocalyx, Lipoteichoic acid, Peptidoglycan

Chapter 4 – Prokaryotic • are unicellular Profiles • Prokaryotes include two small groups of Topics: organisms - the archaeobacteria and the –External Structures photosynthetic plus the large group of true or eubacteria – Envelope –Internal Structures •Prokaryotes are generally small - in the –Cell Shapes, Arrangement, and range of 0.2 to 2.0 µµµm. However, there are Sizes exceptions. Cyanobacteria may be 60 µµµm long

External Structures Flagella

• Flagella • Composed of subunits • Pili and fimbriae • Role - () • • Varied arrangement (ex. Monotrichous, lophotrichous, amphitrichous) • Responsible for swarming in P. aeruginosa

1 Three main parts of the flagella include the , hook, and filament.

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There are 4 types of flagellar arrangement in bacteria – important for movement and useful in Mono Lopho diagnosing particular infections

Monotrichous Amphitrichous Lophotrichous Peritrichous Amphi Peri

The rotation of the flagella enables bacteria Associated with flagella is the to be motile phenomenon of chemotaxis – random ‘tumbles’ followed by directional ‘runs’

Chemotaxis - cells have the capability of responding to chemical attractants

2 Chemotaxis - response to chemical signals Periplasmic or Axial filament –present in some spirochetes RUN

TUMBLE

Pili and fimbriae - Pili are formed on certain bacterial cells and are important for • Attachment attachment, conjugation bridges for transfer • Mating (Conjugation) (transfer of resistance plasmids for example)

- Fimbriae are smaller and are important for attachment – E. coli attachment to intestinal cells

Pili enable conjugation to occur, which is the transfer of DNA from one bacterial cell to another Fimbriae binding to epithelial cells

3 Glycocalyx – outer coating - “Loose” surface on bacteria – 2 types attachment – not very thick – • Capsule – Protects bacteria from of – pneumoniae, Capsule - thick – anthracis protection against • Slime layer phagocytosis – – Enable attachment and aggregation of often associated bacterial cells. Source of ? with increased – Most often associated with the virulence – Griffin’s mode of growth experiments

Bacteria Biofilms Cell envelope - the barrier that separates the environment from the 'living' cell • Composed of , cell and in Gram negative organisms, an outer • Cell Wall = • Cell Membrane = - just us!!!

Cell wall - made up of linked N- Structures associated with gram-positive and gram-negative cell walls acetyl glucosamine (NAG) and N-acetyl muramic (NAM) • Gram POSITIVE cell wall – Thick peptidoglycan (PG) layer – Acidic – and • Gram NEGATIVE cell wall – Thin PG layer – Outer membrane – – Accentuated periplasmic space

4 - Teichoic acid consisting of glycerol, phosphates Cartoon of the NAG and NAM and ribitol is found in polymers in gram-positives .

- Outer membrane - found primarily in Gram - Layers of negatives - (LPS) is a major alternating NAM and component - also called endotoxin - lipid A is a NAG major component of LPS and causes the toxic - Linkage between events of fever and blood vessel dilation observed in NAM from one layer Gram-negative infections. to the NAM of the other one - Periplasmic space - a gap between the cell membrane and the cell wall - particularly evident in Gram negative bacteria.

Linkage of two chains through GRAM NEGATIVE NAM in Gram positive bacteria

GRAM POSITIVE

Both NAG & NAM have tetrapeptides

Nontypical Cell Walls No cell wall = No Peptidoglycan - Mycobacteria - Non Gram positive or Negative - Increased amounts of - Special  ACID-FAST STAINING • Cell membrane contain for stability - classical example is - a common cause of atypical pneumonia - on agar, Mycoplasma looks like a 'fried egg'

Mycobacteria

5 Cell Membrane

• bilayer and integral • Mycoplasma – STEROLS • Function: 1) Selective permeability 2) Energy reactions 3) Synthesis of molecules

Scanning electron micrograph of

Internal Structures

• Cytoplasm • Gelatinous solution containing water • Genetic structures (70-80%), nutrients, proteins, and • genetic material. • Presence of -like filaments =

Prokaryotic Genetic material and structures • Single circular bacterial • • PLASMIDS – Independent circular DNA structures • - 'structures' that have multiple components - responsible for protein synthesis

6 During depleted conditions, some Storage Bodies bacteria (vegetative cell) form into an endospore in order to survive - NUTRITIONAL SOURCE – , - Specific , β- endospore hydroxybutyrate staining techniques - Gas vesicles often make the look like a “safety pin”

- Bacillus and

Endosporulation - a survival mechanism for lean times

Cell shapes, arrangements and sizes

(RIGID) (Flexible)

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Table 4.5

You must know at least 3 features between the 3 domains

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