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Microimm 2500 > Bacteriology > Flashcards

Bacteriology Flashcards

1
Q

What are the 3 domains of life

A

Bacteria, Archaea, Eukaryotes

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2
Q

Prokaryotes

A
  • simplest, smallest and most abundant cells on earth
  • bacteria and archaea
  • lack nucleus and complex organelles
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3
Q

How do bacteria reproduce

A

binary fission

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4
Q

T/F: fast growing bacteria are more efficient/evolved than slow growing bacteria?

A

FALSE

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5
Q

What is the generation time for fast and slow growing bacteria?

A

Fast: ~ 10 mins
Slow: ~ 24 hrs

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6
Q

What are the 3 classifications of bacteria by shape

A

Coccus, Rod, Spirillum

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7
Q

Obligate aerobe

A

requires oxygen for growth (e.g humans)

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8
Q

obligate anaerobe

A

oxygen is toxic for growth

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9
Q

Facultative anaerobe

A

can use oxygen if present, but can also grow without oxygen

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10
Q

Aerotolerant anaerobe

A

does not use oxygen but oxygen is not toxic

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11
Q

Microaerophile

A

grows best with low levels of oxygen

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12
Q

What is a bacterial strain?

A

strains are genetically different bacteria - it is like a “name”
- NOT ALL “e.coli” are the same, there are different strains

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13
Q

Gram Stain

A

Stain used to classify bacteria, created by Hans Christian Gram

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14
Q

What are purple bacteria on the gram stain?

A

Gram Positive

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15
Q

What are pink bacteria on the gram stain

A

Gram Negative

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16
Q

What is the process of Gram Staining?

A
  • take swab of bacteria and put on a glass slide
  • heat the slide
  • flood with crystal violet dye
  • add iodine solution which fixes the purple stain into the cell wall
  • wash cells with alcohol to get wash dye off (for gram positive bacteria, the dye will remain)
  • add counterstain to stain everything that the dye washed off from previously
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17
Q

What are two cases you cannot use the gram stain?

A
  • Mycobacteria (use acid fast)

- bacteria that have no cell wall (mycoplasma)

18
Q

Gram positive cell envelope

A
  • cell wall is outside the cytoplasmic membrane
  • cell wall is very thick and this structure is what maintains the purple
  • no outer-membrane
  • no periplasm
  • have teichoic acids in cell wall
19
Q

Gram Negative Cell Envelope

A
  • has cell wall but it is very thin
  • more complex
  • have a second membrane (outer membrane)
  • between two membranes there is a “periplasm”
  • also have lipopolysaccarides
20
Q

Another name for Bacterial Cell Walls

A
  • also called peptidoglycan
21
Q

Describe bacterial cell walls

A
  • rigid structure surrounds bacteria (like a fence)
  • prevent osmotic lysis
  • gylcan backbone made up of two sugars that are linked together via peptides
  • synthesis of cell wall is a major target for cell antibiotics
22
Q

What are the two sugars that make up the glycan backbone? Of the two sugars, which are cross-linked together via peptides

A

N-Acetylglucosamine (G) and

N-Acetylmuramic acid (M)

23
Q

Three components that make up Lipopolysaccharide (Endotoxins) and their functions

A

O-specific polysaccharide (aka O antigen):

  • that sticks out of the surface of bacteria
  • Immune system can recognize this and develop antibodies against it
  • highly variable

Core polysaccharide:
- Links the O antigen and Lipid A

Lipid A:

  • this is the part that actually sticks into and is part of the membrane
  • Doesn’t vary much
  • Good target for innate immune system to go after and recognize bacteria
  • recognized by innate immune system and cause hyper-inflammation, producing cytokine storm and then septic shock
24
Q

Sometimes bacteria will change this part of the lipopolysaccharide so that it is not recognized by the immune system. Which is it?

A

O antigen

25
Q

Nucleoid

A
  • NOT the nucleus
  • no surrounding membrane
  • Single, circular chromosome (most but not all bacteria)
  • Haploid genomes (one set of chromosome)
26
Q

Plasmids

A
  • Extrachromosomal genetic elements
  • Usually not required for bacterial growth (bacteria in the lab can grow without them being present)
  • Often encode for ‘fitness’ factors (e.g. antibiotic resistance)
  • Can be transferred from bacteria to bacteria
27
Q

Commensalism

A

one benefits without helping or hurting the other (e.g. intestinal bacteria)

28
Q

Mutualism

A

both the host and microbe are benefited

29
Q

Parasitism

A

one benefits (usually the microbe) at the expense of the other (usually the host)

“PARASITE”: usually this term is restricted to eukaryotic pathogens, not bacteria

30
Q

What makes bacterial pathogen successful?

A

Cycle of: Colonization, invasion/toxicity (in host), immune evasion (host response), transmission

31
Q

Virulence factors

A

molecules produced by the pathogen that contribute to disease

32
Q

Examples of Virulence Factors

A

Surface:

  • LPS (endotoxin)
  • Flagella
  • Pili
  • Capsules
  • Surface Proteins
  • Secretion systems

Secreted:
-exotoxins

33
Q

Flagella

A

Structures that allow some bacteria to be motile (chemotaxis)
Counter- Clockwise rotation: move forward

Clockwise rotation: tumble around in random direction

  • Switch between directions and overtime they will move toward attractant
  • If there is no attractant, they randomly tumble/run (no direction)
  • Not like they are steering, it’s a random process
34
Q

Pili (Fimbriae)

A

Primarily involved in attachment to: surfaces, host tissue, other bacteria

35
Q

Capsules

A
  • extracellular structures
  • made of exo-polysaccharides
  • attachment to host tissues
  • protection from hose immune system
  • can sometimes be used in vaccines
  • formation of biofilms
36
Q

Biofilm

A
  • individual cells bind to surface (e.g. teeth) - ATTACHMENT
  • Divide and start to produce capsule (gooey structure) - MICROCOLONY/BIOFILM DEVELOPMENT
  • Eventually matures to biofilm structure - MATURATION
  • NOT a random pile of goo
  • This structure has channels in it to allow nutrients to enter and waste to exit
  • Bacteria at bottom of biofilm will have slower growth
37
Q

Stages of Biofilms

A

Attachement
Microcolony development
Biofilm development
Maturation

38
Q

Endospores

A
  • Highly differentiated cells formed within the parent cell
  • Highly resistant to heat, harsh chemicals and radiation
  • A “dormant” stage of the life cycle
  • made only by gram positive
39
Q

Where are endospores most commonly found?

A

Most common in:

  • Soil
  • Bacillus and Clostridium genera are the best studied
40
Q

Exotoxins

A
  • Highly specialized virulence factors
  • Secreted from bacteria (EXO)
  • Localized infection but your disease is systemic
    (bacteria is only in one place, but the toxin is systemic)
  • E.g. tetanus
41
Q

Examples of Exotoxins

A
  1. Hemolysins - lyses RBCs
  2. toxins that function inside the host cells
  3. Extracellular enzymes – destroy tissue
  4. Super-antigens – function to turn on adaptive immune systems
42
Q

Bacteria as intracellular pathogens

A
  • Are taken up and survive within phagocytic cells (e.g. macrophages)
  • Some ‘force’ their own uptake into epithelial cells
  • Allows bacteria to hide from different components of the immune system

Microimm 2500 (8 decks)

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