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DWT > Bacteriology 1: Introduction > Flashcards

Bacteriology 1: Introduction Flashcards

1
Q

Three domains of life

A

Eukarya
Prokaryotes: Archaea & Bacteria

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2
Q

Eukarya

A

Single-celled or multi-celled organisms enclosed by a membrane.

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3
Q

Archaea

A

Single-celled microorganisms. Prokaryotes developed separately from bacteria

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4
Q

Bacteria

A

Single-celled organisms lacking a membrane-bound nucleus and other membrane bounds organelles.
**Smaller and less complex than eukarya.

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5
Q

Characteristics unique to bacteria

A

-Rigid cell walls with PEPTIDOGLYCAN
- No membrane bound organelles
-No nucleolus, mitochondria, ER, or golgi
-Multiply by binary fission
-Usually <5 micrometers

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6
Q

Bacteria (prokaryotes) Vs Eukaryotes

A

See image

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7
Q

Bacteria Classification categories

A

-Morphology
-Biochemical reactions
-Serology
-Nucleic Acid profiles

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8
Q

Bacterial morphology

A

Rods vs Cocci

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9
Q

Bacterial Ultrastructures

A

Structures that have potential to make bacteria infectious
- Cell envelope
- Cytoplasm
-Other: Flagells, Pili, Spores, Biofilm

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10
Q

Cell envelope structures

A
  • Capsule or Slime layer (+/-)
  • Cell Wall
  • Cytoplasmic membrane
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11
Q

Cytoplasm Structures

A

Nucleoid
Ribosomes

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12
Q

Capsule and Slime layer.
What is it? What is the function?

A

Gelatinous material lying outside the cell wall (Goop)
- Carbohydrates
- Sometimes polypeptides (Sticky goop)
- Very variable (antigenically diverse)
- Function: help adherence, anti-phagocytic, prolong survival in the environment

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13
Q

Cell wall
What is it? What does it influence?

A

-Gives bacteria shape and rigid structure, ~20% of bacteria dry weight.
-Different structures and chemical composition influences the pathogenicity and staining characteristics

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14
Q

Types of bacteria/Staining methods

A

Gram positive
Gram negative
Acid fast

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15
Q

Gram staining

A

Fixation
Crystal violet (gram positive)
Iodine treatment
Decolorization
Counter stain with safranin

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16
Q

Gram staining types of damage affecting outcome

A

Heat
Age
Antibiotics
** All damage the peptidoglycan cell wall **

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17
Q

Gram Negative cell wall structure

A

Thin peptidoglycan cell wall that is also surrounded by an outer membrane containing lipopolysaccharides and porins.

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18
Q

Gram Positive cell wall structure

A

Lack an outer membrane but are surrounded by layers of peptidoglycan

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19
Q

Porins

A

Porins are pore proteins contained in the outer membrane of Gram-negative bacteria and they mediate the diffusion of small hydrophilic molecules. Thus allow in antibiotics

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20
Q

Lipopolysaccharides

A

provide structural integrity and a permeability barrier to protect the bacterial cell from the entry of deleterious molecules such as toxins and bile salts during its inhabitation in the gastrointestinal tract

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21
Q

Gram-Neg vs Gram-Pos cell wall composition

A

See image

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22
Q

Why do we care Gram-Neg or Gram-Pos?

A
  • Help with diagnosis
  • Some ABX are effective with only one or the other
  • Few ABX are broad to both
  • Antimicrobial therapy is most effective when it is narrow spectrum!!!
23
Q

Gram-Pos bacteria
Characteristics?
Staining qualities?

A

-Simpler than Gram-neg
-Thicker more uniform cell wall, composed of peptidoglycan and teichoic acid
-More resistant to mechanical damage
-Peptidoglycan is target for ABX and lysozyme
- Neutralized by detergents
-Retain Crystal violet staining through decolorization process causing cells to appear PURPLE/BLUE

24
Q

Gram-Neg bacteria
Characteristics?
Staining qualities?

A
  • More complex than gram pos
    -Outer-membrane has LPS. MAJOR virulence factor
    -Periplasmic space with small amount of peptidoglycan
  • Outer-membrane excludes hydrophobic molecules rendering them resistant to detergents
25
Q

What is a detergent?

A

water-soluble cleansing agent which combines with impurities and dirt to make them more soluble

26
Q

Acid Fast bacteria
Characteristics?
Staining qualities?
Additional molecules/fuction?

A

-Cell Envelope contains additional molecules.
— Mycolic acid, glycolipids, fatty acids, and polypeptides
- Additional molecules makes staining difficult
-Additional molecules allows them to survive in the environment and survive inside cells
-Additional molecules can be a target for certain ABX

27
Q

Flagella

A

Important for motility

28
Q

Fimbriae (pili)

A

Important for adherence

29
Q

Spores

A

Inactive form of bacteria. Important for long term survival and physical resistance

30
Q

States bacteria may exist in

A

Planktonic (Free)
Sessile (attached)

31
Q

What is a biofilm? How does it act?

A

Some bacteria create this to exist in sessile form.
- Biopolymer matrix enclosing a population of bacteria to each-other and/or a surface
-Acts as an organism through “quorum sensing”

32
Q

Biofilm “quorum sensing”

A

Activates biofilm creation when planktonic bacteria numbers are high and activates biofilm degradation when planktonic bacteria numbers are low

33
Q

How do biofilms help in the pathogenesis of bacteria?

A

-Aid colonization
-Avoid phagocytosis
-Avoid antibiotics

34
Q

What is in bacterias cytolasm?

A

Ribosomes
Granules
Nucleoid

35
Q

What is a bacterial nucleoid and what does it contain?

A

An irregularly shaped region in a prokaryotic cell that contains most of the genetic material.
Also contains: plasmids and phages

36
Q

How do bacteria increase in numbers?

A

-Binary fission

37
Q

What is generation time and what influences it?

A

Length of time required for a single bacterium to yield two daughter cells.
- Genetics (type of bacteria)
-Nutritional factors (nutrient media)
-Chemical and physical and environmental factors

38
Q

Define clonal expansion and what it represents for bacterial growth

A
  • Clonal expansion is the binary fission of a bacterium into a colony.
    -Small colony = slow growing/long generation time
    -large colony = fast growing/short generation time
39
Q

Optimal conditions for bacterial growth

A

pH: neutral to alkaline
Tonicity: isotonic
Temperature: 98.6. (Range: 68 -113)
— Listeria = cold 39
Atmospheric condition: vary

40
Q

Categories of atmospheric requirements of bacteria

A

Strict aerobes: Require O2
Strict anaerobes: Killed by O2
Facultative anaerobes: Grow with/without O2
Microaerophiles: Require reduced O2 (<20%) and some like increased CO2

41
Q

What is important to know the atmospheric conditions of bacteria?

A
  1. types and location of diseases they can cause
  2. Your approach to diagnosis of these infection
  3. How to treat
42
Q

What are the genetic elements of bacteria?

A
  1. Bacterial genome
  2. Plasmids
  3. Bacteriophage
43
Q

Types of bacterial genomes?

A
  • Haploid, circular chromosome (1n)
    -Diploid, double stranded DNA
44
Q

What are plasmids?

A

Small circular DNA which can autonomously replicate. May encode virulence (toxin) and ABX resistance.

May be stand alone or integrated into bacterial genome
May transfer from one bacteria to the next

45
Q

What are bacteriophages

A

Viruses which infect bacteria.
-Usually integrate into the bacterial genome but may stand alone.
-May encode virulence genes

46
Q

Bacterial variation

A

Due to either phenotypic variants or genotypic variants

47
Q

Bacterial genotypic variants

A
  1. Mutation
  2. Recombination
  3. Transposition
48
Q

Bacterial genotypic variants- mutations

A

Change in chromosomal DNA

49
Q

Bacterial genotypic variants- Define Recombination. List possible ways.

A

Exchange of DNA between Bacteria
1. transduction: Phage mediated transfer
2. conjugation: plasmid mediated transfer
3. Transformation: uptake of naked segment of DNA

50
Q

What do genotypic variants usually lead to?

A

Morphological changes
Virulence

51
Q

Where on the body is strictly anaerobic?

A

surface of epithelium:
- Lumen of GI tract
- Btwn teeth and gums
- Urogenital tract

52
Q

Bacterial genotypic variants- Transposition

A

Relocation of parts of DNA in the genome mediated by transposable elements

53
Q

When do we have strictly anaerobic tissues?

A

If necrosis is present

DWT (28 decks)

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