9/2 Chapter 3: Bacteria and Archaea (3.2 learning modules to Pili and Nanotubes)

What are the external structures of a prokaryotic cell from outside to inside?

1. Flagella

2. Fimbriae

3. Pili

4. Nanotubes/nanowires

5. S Layer

6. Glycocalyx

What are the differences between the slime layer and capsule of a glycocaylx?

1. Slime layer: loose (to bacteria cell wall), protects against loss of water and nutrients (like jelly that can absorb water)

2. Capsule: more tightly bound (to cell wall), denser, and thicker

• Important when dealing with pathogens (Immune cells can’t grab capsule as easily which is important for pathogens)

What are the external structures of a prokaryotic cell from outside to inside? (Describe Flagella primary function and its 3 parts)

Primary function is motility (movement can swim/move which helps it run from pathogens)

• The structure is three distinct parts:

1. Filament: (outmost part)

2. Hook (sheath): 360 degree connect anchor to filament

3. Basal body: Anchors in bacteria strongly

What is the arrangement of flagella? (What is polar arrangement and the 3 types? What is the other arrangement called)

Polar arrangement: flagella attached at one or both ends of the cell (There are 3 types)

1. Monotrichous: single flagellum

2. Lophotrichous: small bunches or tufts of flagella emerging from the same site (All from one point)

3. Amphitrichous: flagella at both poles of the cell

• Peritrichous arrangement: flagella are dispersed randomly over the surface of the cell

What is the flagellar movement: chemotaxis? What are the two types of chemotaxis?

Chemotaxis (Chemical Movement): movement of bacteria in response to chemical signals:

• There is Positive vs Negative chemotaxis (Toward or Away)

• Ex: Toward nutrients or away from disinfectants

What are the two stages of flagella function motility when it comes to moving? Not positive and negative, but ______ and ______

1. Run: rotation of flagellum counterclockwise, resulting in a smooth linear direction (Distance traveled)

2. Tumble: reversal of the direction of the flagellum, causing the cell to stop and change course (Change direction)

• They don’t all run in 1 direction; They run in a zig-zag pattern

What are the external structures of a prokaryotic cell from outside to inside? (Describe Fimbriae composition and what it allows for)

• Small, bristle-like fibers sprouting off the surface of many bacterial cells (Shorter than flagella and present uniformly all over surface of bacteria in large numbers)

• Allow tight adhesion between fimbriae and epithelial cells, allowing bacteria to colonize and infect host tissues (ex: can attach membrane like UTT LISTEN TO LECTURE FOR THIS)

What are the external structures of a prokaryotic cell from outside to inside? (Describe what the Pilus/Pili is used for and in what type of bacteria is it well characterized in)

• Used in conjugation between bacterial cells

• Well characterized in gram-negative bacteria

• Type IV pilus can transfer genetic material, act like fimbriae and assist in attachment, and act like flagella and make a bacterium motile

What are the #’s of pili compared to fimbriae? What do the pili help with?

They are present in large #’s but less than fimbriae and are short

• Helps with motility and attachment

What is Conjugation between bacteria? What two things does conjugation help with? Provide one example of how conjugation works.

Two bacteria form a bridge of pili that info can be passed between them

• Helpful for plasmid DNA and resistance to antibodies

• Ex: One bacteria transfers plasmid making 2 resistant bacteria and on; it just grows in numbers