Microbial structure Flashcards

1
Q

What is in a bacteria cell

A
  • Glycocalyx (capsule/slime)
  • Cell wall
  • Plasma membrane
  • Nucleoid
  • Ribosome
  • Plasmid
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2
Q

What is the structure of the capsule

A

Tightly organised polysaccharide layer that excludes small particles. Typically adhere firmly to cell wall

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2
Q

What is the glycocalyx composed of

A

Capsule and slime

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3
Q

What is the function of the capsule

A
  • Protects cell from phagocytosis and desiccation
  • Promotes adherence to host tissues
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4
Q

What is the structure of the slime

A

More easily deformed polysaccharide layer, less tightly organised and doesn’t exclude small particles . Loosely attached to cell surface and can be easily lost

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5
Q

What is the function of the slime

A

Protects cell from immune response. It can prevent access to antibodies

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6
Q

What are pili composed of

A

It is composed of oligomeric pilin proteins

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7
Q

What are the pili appendage used for and how does it occur

A

Bacterial conjugation. It forms a tube to enable transfer of plasmids between bacteria

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8
Q

What is the function of pili

A

It is highly antigenic and plays role in attachment

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9
Q

What are fimbriae

A

They are not on all bacteria and may contain lectins

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10
Q

What are lectins

A

They recognise oligosaccharide units on host cells

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11
Q

What is the function of fimbriae

A

They facilitate bacterial attachment to host surfaces

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12
Q

What are flagella

A

They are organs of locomotion, composed of flagellin protein

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13
Q

How are flagella driven

A

A rotatory engine at anchor point on inner cell membrane

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14
Q

What are the 4 classifications of flagella

A
  • Monotrichous - 1 flagellum
  • Amphitrichous - 1 flagellum on each end
  • Lophotrichous - Multiple flagella on one end
  • Peritrichous - Lots of flagella around
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15
Q

What are spores

A

They are a metabolically inert form triggered by adverse environmental conditions. They are adapted for long term survival allowing regrowth under suitable conditions

16
Q

What is gram staining

A

It differentiates bacterial species into 2 groups: gram positive and gram negative

17
Q

How does gram staining differentiate

A

Based on chemical and physical properties of the cell walls

18
Q

What are the components of the cell wall

A
  • Peptidoglycan
  • LTA - gram positive bacteria
  • LPS - gram negative bacteria
  • Outer membrane proteins
19
Q

What is peptidoglycan

A
  • Polymers of sugars and amino acids
  • Forms mesh-like layer outside plasma membrane
  • Sugar component
20
Q

What is LTA

A
  • Complex of teichoic acid and lipids
  • Provides cell rigidity
  • Recognised by host immune cells
21
Q

What is LPS

A
  • Essential for function of outer membrane
  • Elicits potent immune and inflammatory host responses
  • Produces endotoxins
22
Q
A