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Block 6 Week 3 > Kozel: Basic Bacteriology > Flashcards

Kozel: Basic Bacteriology Flashcards

1
Q

These are the smallest infectious particles

A

viruses

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2
Q

Why are viruses considered true parasites?

A

they require host cells for replication

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3
Q

These are prokaryotic simple unicellular organisms that reproduce by asexual division

A

bacteria

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4
Q

Do bacteria have a nuclear membrane, mitochondria, golgi, or ER?

A

no!

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5
Q

These are eukaryotic, more complex organisms with a well defined nucleus, mito, Golgi bodies, and ER

A

fungi

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6
Q

What do fungi membranes contain?

A

a unique sterol called ergosterol

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7
Q

What is replication like for fungi?

A 
unicellular forms (like yeast) divide asexually
filamentous forms (like mold) can replicate sexually or asexually
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8
Q

These are eukaryotic organisms - they are the most complex of the microbes. Some are unicellular, some are multicellular.

A

parasites

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9
Q

What are some different ways that bacteria might be classified?

A

shape
arrangement
cell wall structure
presence of absence of antigen

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10
Q

What are three SHAPE classifications for bacteria?

A

spherical - coccus
rod - bacillus
spiral - spirillum

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11
Q

What are two ARRANGEMENT classifications for bacteria?

A

chains - single division plane

clumps - multiple division planes

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12
Q

What are three CELL WALL STRUCTURE classifications for bacteria?

A

gram positive
gram negative
acid fast

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13
Q

List three more ways that bacteria might be classified.

A
  1. metabolism - aerobic, facultative anaerobe, anaerobic
  2. ability to lyse erythrocytes - hemolytic, non-hemolytic
  3. fermentation of sugars - fermenter, non-fermenter
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14
Q

Microbes can also be classified based on their (blank), which (blank) they affect, and their means of (blank)

A

growth habit - extracellular (controlled by antibody), intracellular (controlled by T-cell immunity), toxin producer, pyogenic cocci; systems; acquisition (foodborne, zoonotic)

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15
Q

Why is bacterial structure important to consider?

A
  1. difference from mammalian cells provide targets for antimicrobial agents
  2. bacterial structures contribute to pathogenesis
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16
Q

What are the contents of the cytoplasm of bacteria?

A
  1. bacterial chromosome (single dsDNA in a circle, no nucleus)
  2. plasmids (small, extra chromosomal DNA)
  3. ribosomes (70S)
  4. cytoplasmic membrane *no sterols like cholesterol except in mycoplasma
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17
Q

What do plasmids do?

A

they are extra chromosmal DNA, they may code extra, non-essential functions (ex: Ab resistance)

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18
Q

What are the 2 subunits of the 70s bacterial ribosome?

A

30S and 50S

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19
Q

What are the steps in peptidoglycan biosynthesis?

A
  1. synthesis of a water-soluble precursor
  2. attachment of precursors to a membrane lipid
  3. formation of linear polymers outside the membrane (trans glycosylation)
  4. cross-linking of polymers into 3D matrix (trans peptidization)
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20
Q

Describe the structure of peptidoglycan layer in bacterial cell walls.

A

crystal lattice structure with linear chains of two alternating amino sugars - N-acetylglucosamine and N-acetylmuramic acid. The sugars are connected by a Beta-1,4-glycosidic bond. Each N-acetylmuamic acid is attached to a short amino acid chain (Ala-Glu-Lys-Ala-Ala). Cross-linking between amino acids of different linear amino sugar chains occurs with the help of transpeptidase and results in a 3D structure.

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21
Q

Describe the steps in a gram stain

A
  1. heat fix
  2. crystal violet - stains cell wall
  3. gram’s iodine - precipitates crystal violet and causes the complex to be trapped in thick cell wall of gram positive bacteria (that’s why they stain purple)
  4. decolorizer (alcohol) - removes crystal violet/iodine complex from thin gram negative cell walls
  5. safranin - counterstains the decolorized gram negative cells
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22
Q

So what color will gram positive bacteria stain? What color will gram negative bacteria stain?

A

PURPLE; RED

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23
Q

What is one factor that influences how the gram stain will turn out?

A

the integrity of the cell wall - can be weakened by old age, antibiotics, or too much heat fixation

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24
Q

Can a gram positive bacteria stain negative? Can a gram negative bacteria stain positive?

A

yes! ; no

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25
Describe the cell wall of a gram positive bacteria.
``` thick, multilayered primary constituent is peptidoglycan surrounds the cytoplasmic membrane degraded by lysozyme contains teichoic acids ```
26
What is the primary constituent of gram positive cell wall?
peptidoglycan
27
What enzyme can degrade a gram positive cell wall?
lysozyme
28
What are two acids that are found in gram positive bacteria?
teichoic acid - covalently linked to peptidoglycan, several functions in virulence lipoteichoic acid - teichoic acid with fatty acid, anchored in cytoplasmic membrane, stimulates innate host responses in a manner similar to gram negative bacteria
29
Describe the cell wall of gram negative bacteria.
TWO layers over the cytoplasmic membrane. Thin peptidoglycan layer with no teichoic acids or lipoteichoic acids. Outer membrane that is unique to gram negative bacteria.
30
Does the peptidoglycan layer of gram negative bacteria have teichoic or lipoteichoic acids?
no; only gram positive bacteria
31
The outer membrane of gram negative bacteria has two layers, inner and outer. What are they made of?
inner layer: phospholipids similar to other bacterial membranes outer layer: primarily LPS **porins which allow small hydrophilic molecules to pass through
32
These are protein channels located in the outer membrane of gram negative bacteria. They can provide targets for vaccines.
porins
33
LPS is an endotoxin found in gram negative bacteria. What are its three components?
1. Lipid A - responsible for endotoxin activity 2. core polysaccharide - 9-12 sugars with one unusual sugar (KDO) 3. O antigen - highly antigenic, used to classify bacteria
34
This is a highly toxic endotoxin that is shed into the body during infection. It has numerous biological activites.
Lipopolysaccharide - LPS
35
Compare gram POSITIVE and gram NEGATIVE bacteria: ``` Outer membrane? Cell wall? LPS/endotoxin? Teichoic/lipoteichoic acids? Spores? Capsules? Lysozyme? Penicillin? Exotoxins? ```
``` no; yes thick; thin no; yes yes; no some; no sometimes; sometimes sensitive to lysozyme; resistant more sensitive to penicllin; more resistant common; sometimes ```
36
This external structure is usually a polysaccharide. It is antiphagocytic, and a very common vaccine target.
Capsule
37
What is one microbe that has a poly-glutamic acid capsule?
Bacillus anthracis (anthrax)
38
These are rope-like propellers that are coiled in protein subunits, and provide motility
flagella
39
These are hair like structures with adherence factors
fimbriae
40
What is unique about mycobacteria?
its peptidoglycan is intertwined with a polymer of arabinogalactan
41
What surrounds mycobacteria?
wax-like lipid coat cord factor wax D
42
Mycobacteria are resistant to (blank) and many stains. They are considered (blank).
disinfectants; acid fast
43
What is one exception in the mycobacteria category?
mycoplasma **no peptidoglycan incorporates host sterols into membranes
44
Are spores made by gram positive or gram negative bacteria?
only gram positive
45
What are the contents of a spore?
complete copy of chromosome minimal proteins/ribosomes high conc of dipicolinic acid bound to Ca++
46
What triggers sporulation vs germination?
sporulation is triggered by depletion of nutrients, while germination is triggered by some form of stressor, water, and a triggering nutrient
47
Spores have a high concentration of (blank), which is unique to spores, and binds to Ca++
dipicolinic acid
48
What nutritional requirements do bacteria have for growth?
``` carbon nitrogen growth factors inorganic ions O2 ```
49
What physical requirements do bacteria have for growth?
Red-ox potential Temperature *most are mesophils (10-45 C) H+ concentration Osmotic conditions
50
This is the most efficient form of energy production for bacteria. O2 is the terminal electron receptor.
aerobic respiration
51
This is a less efficient means of energy production than both aerobic and anaerobic respiration. An organic molecule is the terminal electron receptor.
fermentation
52
In this form of respiration, an inorganic compound is the terminal electron acceptor (ex: sulfate or carbonate)
anaerobic respiration
53
List the order of different modes of energy production from most efficient to least
aerobic respiration > anaerobic respiration > fermentation
54
What does it mean to be an obligate aerobe? What is one pitfall of this type?
requires molecular O2 for metabolism; may produce ROS in the process
55
What does it mean to be facultatively anaerobic?
can grow in the presence or absence of O2; O2 will be the terminal e- acceptor if O2 is present; if not, other e- acceptors are utilized
56
What does it mean to be an obligate anaerobe?
O2 is toxic; inorganic compound is terminal e- acceptor
57
How can you determine bacterial mass?
dry weight of bacteria | look at turbidity (optical density) when you move it around
58
How can you determine the cell number in a bacterial mass?
direct counting by microscope prepare dilutions culture in petri dish directly count colonies
59
What are the phases in the bacterial growth curve?
1. lag phase (increase in cell size but cells are just growing - little division) 2. exponential growth (linear increase - cell number and mass increase) 3. stationary phase (plateau - accumulation of waste and ran out of nutrients) 4. death or decline (linear decrease)
60
Which phase of bacterial growth provides the time of maximal sensitivity to penicillin?
exponential growth phase
61
Transpeptidases are targets of the beta lactam class of antibiotics. What is the function of transpeptidases in cell wall synthesis?
Generate cross-linking between the peptides on peptidoglycan to produce a complex matrix
62
What enzymes do this? Catalyze formation of the N-acetyl glucosamine – N-acetyl muramic acid disaccharide Cross-link a N-acetyl glucosamine – N-acetyl muramic acid disaccharide to a growing polysaccharide chain
transglycosidase
63
What is the location of porins in the bacterial cell wall?
outer membrane of gram-negative bacteria

Block 6 Week 3 (6 decks)

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