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Infectious Diseases > Bacteriology > Flashcards

Bacteriology Flashcards

1
Q

Describe prokaryotes…

A
  • Bacteria & Archaea
  • Single-celled
  • Lack a true nucleus
  • Lack membrane bound organelles
  • Single chromosome
  • Undergo replication by binary fission
  • Haploid
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2
Q

Describe Eukaryotes…

A
  • Multiple celled
  • All plants, animals and higher protists
  • Have a true nucleus
  • Membrane bound organelles
  • Multiple chromosomes
  • Undergo mitotic replication
  • Diploid
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3
Q

Describe the cell wall…

A
  • surrounds the cytoplasmic membrane of most bacteria
  • protects against mechanical damage
  • Responsible for shape, cell division and antigenic properties
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4
Q

What is the major component of cell walls?

A
  • Network of modified sugar polymers cross-linked by short polypeptides
  • Anchors other molecules that extend from surface
  • Encloses entire bacterium
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5
Q

Describe gram positive bacteria…

A
  • Two layers
  • Thick peptidoglycan layer
  • Teichoic and Lipoteichoic
  • Stain purple
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6
Q

Describe gram negative…

A
  • Three layers
  • Thin peptidoglycan layer
  • Phospholipids, lipoproteins, lipopolysaccharides
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7
Q

Describe the gram staining process…

A
  1. Make a bacterial smear
  2. Fix cells to a slide
  3. Stain with crystal violet
  4. Fix the stain with iodine
  5. Decolourise with alcohol
  6. Counter stain with saffranin
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8
Q

Describe the cytoplasmic membrane…

A
  • Discrete lipid layer of the cytoplasm just beneath the cell wall
  • Lipid layer between two protein layers
  • Osmotic barrier
  • – passive and active
  • – Semi-permeable
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9
Q

Describe the cytoplasmic contents…

A
  • Nuclear material
  • Inclusion bodies
  • Ribosomes
  • Plasmids
  • Ribosomes
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10
Q

Describe the capsule……

A
  • Made of polysaccharides and polypeptides
  • Attached to the cell wall of some bacteria
  • Protects against phagocytosis
  • Enhances adherence
  • Require different stains
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11
Q

Describe the Flagella…

A
  • Thin whiplike structure
  • Can only be seen by special staining
  • Used for locomotion in some bacteria
  • Can see motility in semi-solid or liquid
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12
Q

Describe fimbriae…

A
  • Fine filamentous appendages
  • mostly on gram -ve bacteria
  • Can only be seen by EM
  • Two types:
  • – Short attachment pili for adhesion
  • – Long pili for sex
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13
Q

Describe endospores…

A
  • Produced by organisms in Bacillus and Clostridium
  • Resistant
  • Enables the bacteria to survive due to being resistant to:
    • High temperatures
    • Most disinfectants
    • Desiccation
    • Low energy radiation
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14
Q

Describe the process of Binary Fission…

A
  1. Cell elongates and DNA is replicated
  2. Cell wall and plasma membrane start dividing
  3. Wall forms completely around the dividing DNA
  4. Cells separate as two identical daughter cells
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15
Q

What are the the steps in Bacterial Growth…

A
  1. Lag Phase
  2. Log Phase
  3. Stationary Phase
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16
Q

What occurs in the Lag Phase?

A
  • Little or no increase in growth
  • Increase in metabolic activity
  • Bacteria adapting to new media
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17
Q

What occurs in the Log Phase?

A
  • Cells divide at a constant and maximum rate by binary fission
  • Numbers increase with a linear relationship with time
  • -Youthful population
  • May be sensitive to antimicrobial agents
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18
Q

What occurs in the stationary phase?

A
  • Decrease in growth rate
  • no nutrients
  • Toxins accumulate
  • May show changes in staining?
19
Q

At which stage in bacterial growth are bacterial most sensitive to antimicrobial agents?

A

The Log Phase

20
Q

What are the major requirements for bacterial growth?

A
  • Organic Nutrients
  • Carbohydrates
  • Proteins
  • Lipids
  • Carbon
  • Nitrogen
  • Growth Factors
  • inorganic salts
21
Q

How to autotrophic bacteria make their own nutrients?

A

Using CO2 and inorganic salts

22
Q

Which inorganic salts are necessary for co-factors in enzyme systems?

A
  • P
  • Mg
  • Fe
  • Mn
  • Ca
23
Q

What do heterotrophic bacteria require for an energy source?

A
  • Organic Carbon

- Amino acids/protein as a source of Nitrogen

24
Q

What are strict aerobes?

A

Grow only in presence of air or free O2

25
Q

What are microaerophils?

A

Require low O2 for growth

  • higher O2 inhibits growth
  • energy obtained from aerobic respiration
26
Q

What are obligate anareobes?

A

Grow only in the absence of O2

- anaerobic respiration/ fermentation

27
Q

What are Aerotolerant anaerobes?

A

Can’t use O2 to transform energy but can use it to Grow

28
Q

What are facultative anaerobes?

A

Grow with or with out O2

  • Aerobic if O2 present
  • Anaerobic if no O2 present
29
Q

What are psychrophiles?

A

Cold loving bacteria

-5 to 5

30
Q

What are mesophiles?

A

Grow best at moderate temperatures

25-45

31
Q

What are thermophiles?

A

Heat-loving bacteria

45-70

32
Q

What are hyperthermophiles?

A

Grow at v high temperatures
70-110
- usually archaea

33
Q

What pH do neutrophiles prefer?

A

5-8

34
Q

What pH do acidophiles prefer?

A

<5.5

35
Q

What pH do allaliphiles prefer?

A

> 8.5

36
Q

What type of osmotic media to most bacteria prefer?

A

Isotonic media

- too concentrated or too dilute means bacteria can’t grow in media as they are limited by a semi-permeable membrane

37
Q

What is the period of incubation?

A

The time required for visible growth

- depends on generation time

38
Q

How well can bacteria survive desiccation?

A

Bacteria have varying ability to survive desiccation.

39
Q

Is light or dark more favourable for bacteria?

A

Dark

- UV rays are bactericidal

40
Q

What are the types of media?

A
  • Basal
  • Selective
  • Differential
  • Enrichment
41
Q

Describe basal media…

A
  • Fat, protein and carbs

- may have added animal serum to produce a complete medium

42
Q

Describe Selective media…

A
  • Designed to suppress the growth of some microorganisms while allowing growth of others
  • addition of antimicrobial, salt. anti-fungal properties etc.
43
Q

Describe Differential media…

A
  • Allows the growth of more than one microorganism of interest
  • used to differentiate different types of microorganisms based on colonies
  • contains specific substrate and indicator
  • – dyes or chemicals
44
Q

Describe Enrichment media…

A
  • Media that has been supplemented with highly nutritious growth factors

Infectious Diseases (3 decks)

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