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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
Q

Describe the cell wall of a gram positive bacteria.

A 
thick, multilayered
primary constituent is peptidoglycan
surrounds the cytoplasmic membrane
degraded by lysozyme
contains teichoic acids
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26
Q

What is the primary constituent of gram positive cell wall?

A

peptidoglycan

27
Q

What enzyme can degrade a gram positive cell wall?

A

lysozyme

28
Q

What are two acids that are found in gram positive bacteria?

A

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
Q

Describe the cell wall of gram negative bacteria.

A

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
Q

Does the peptidoglycan layer of gram negative bacteria have teichoic or lipoteichoic acids?

A

no; only gram positive bacteria

31
Q

The outer membrane of gram negative bacteria has two layers, inner and outer. What are they made of?

A

inner layer: phospholipids similar to other bacterial membranes
outer layer: primarily LPS

**porins which allow small hydrophilic molecules to pass through

32
Q

These are protein channels located in the outer membrane of gram negative bacteria. They can provide targets for vaccines.

A

porins

33
Q

LPS is an endotoxin found in gram negative bacteria. What are its three components?

A
  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
Q

This is a highly toxic endotoxin that is shed into the body during infection. It has numerous biological activites.

A

Lipopolysaccharide - LPS

35
Q

Compare gram POSITIVE and gram NEGATIVE bacteria:

Outer membrane?
Cell wall?
LPS/endotoxin?
Teichoic/lipoteichoic acids?
Spores?
Capsules?
Lysozyme?
Penicillin?
Exotoxins?
A 
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
Q

This external structure is usually a polysaccharide. It is antiphagocytic, and a very common vaccine target.

A

Capsule

37
Q

What is one microbe that has a poly-glutamic acid capsule?

A

Bacillus anthracis (anthrax)

38
Q

These are rope-like propellers that are coiled in protein subunits, and provide motility

A

flagella

39
Q

These are hair like structures with adherence factors

A

fimbriae

40
Q

What is unique about mycobacteria?

A

its peptidoglycan is intertwined with a polymer of arabinogalactan

41
Q

What surrounds mycobacteria?

A

wax-like lipid coat
cord factor
wax D

42
Q

Mycobacteria are resistant to (blank) and many stains. They are considered (blank).

A

disinfectants; acid fast

43
Q

What is one exception in the mycobacteria category?

A

mycoplasma
**no peptidoglycan
incorporates host sterols into membranes

44
Q

Are spores made by gram positive or gram negative bacteria?

A

only gram positive

45
Q

What are the contents of a spore?

A

complete copy of chromosome
minimal proteins/ribosomes
high conc of dipicolinic acid bound to Ca++

46
Q

What triggers sporulation vs germination?

A

sporulation is triggered by depletion of nutrients, while germination is triggered by some form of stressor, water, and a triggering nutrient

47
Q

Spores have a high concentration of (blank), which is unique to spores, and binds to Ca++

A

dipicolinic acid

48
Q

What nutritional requirements do bacteria have for growth?

A 
carbon
nitrogen
growth factors
inorganic ions
O2
49
Q

What physical requirements do bacteria have for growth?

A

Red-ox potential
Temperature *most are mesophils (10-45 C)
H+ concentration
Osmotic conditions

50
Q

This is the most efficient form of energy production for bacteria. O2 is the terminal electron receptor.

A

aerobic respiration

51
Q

This is a less efficient means of energy production than both aerobic and anaerobic respiration. An organic molecule is the terminal electron receptor.

A

fermentation

52
Q

In this form of respiration, an inorganic compound is the terminal electron acceptor (ex: sulfate or carbonate)

A

anaerobic respiration

53
Q

List the order of different modes of energy production from most efficient to least

A

aerobic respiration > anaerobic respiration > fermentation

54
Q

What does it mean to be an obligate aerobe? What is one pitfall of this type?

A

requires molecular O2 for metabolism; may produce ROS in the process

55
Q

What does it mean to be facultatively anaerobic?

A

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
Q

What does it mean to be an obligate anaerobe?

A

O2 is toxic; inorganic compound is terminal e- acceptor

57
Q

How can you determine bacterial mass?

A

dry weight of bacteria

look at turbidity (optical density) when you move it around

58
Q

How can you determine the cell number in a bacterial mass?

A

direct counting by microscope
prepare dilutions
culture in petri dish
directly count colonies

59
Q

What are the phases in the bacterial growth curve?

A
  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
Q

Which phase of bacterial growth provides the time of maximal sensitivity to penicillin?

A

exponential growth phase

61
Q

Transpeptidases are targets of the beta lactam class of antibiotics. What is the function of transpeptidases in cell wall synthesis?

A

Generate cross-linking between the peptides on peptidoglycan to produce a complex matrix

62
Q

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

A

transglycosidase

63
Q

What is the location of porins in the bacterial cell wall?

A

outer membrane of gram-negative bacteria

Block 6 Week 3 (6 decks)

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