Basic Bacteriology-Kozel Flashcards
1
Q
Which microbe does this describe: Smallest infectious particles; 18-600 nanometers; True parasites – require host cells for replication?
A
Viruses
2
Q
Once again, how large are viruses?
A
18-600 nanometers
3
Q
Describe bacteria. How do they reproduce?
A
Simple unicellular organisms – no nuclear membrane, mitochondria, Golgi or ER
**asexual reproduction
4
Q
T/F Bacteria are eukaryotes.
A
FALSE!! They are prokaryotes.
5
Q
How large are bacteria?
A
1-20 micrometers
6
Q
What does prokaryote mean?
A
primitive nucleus
7
Q
What does eukaryote mean?
A
true nucleus
8
Q
T/F Fungi are eukaryotes.
A
True!! Whoa
9
Q
Which microbe does this describe? More complex – well-defined nucleus, mitochondria,; Golgi bodies and ER; Membranes contain a unique sterol - ergosterol
A
Fungi
10
Q
Describe the replication of fungi.
A
Unicellular (yeast) – asexual
Filamentous (mold) – can replicate sexually or asexually
11
Q
Once again, what is the name of the sterol in the membrane of fungi?
A
ergosterol
12
Q
Are parasites prokaryotic or eukaryotic? How large are they?
A
1-2 micrometers (protozoa) to 10 meters (tapeworms)
Eukaryotes!
13
Q
Are parasites multicellular or unicellular?
A
They can be either! They are the most complex of the microbes. And the largest potentially!
14
Q
What is the most common sterol in our membranes?
A
cholesterol!
15
Q
What are the some of the ways that you can classify bacteria?
A
Shape Arrangement Cell Wall Structure Antigenic Metabolism Ability to lyse erythrocytes fermentation of sugars
16
Q
What are the 3 shapes of bacteria?
A
Spherical - coccus
Rod - bacillus
Spiral - spirillum
17
Q
What are the 2 arrangements of bacteria?
A
Chains – single division plane
Clumps – multiple division planes
18
Q
What are the different cell wall structures of bacteria?
A
Gram positive
Gram negative
Acid fast-mycobacterium
19
Q
H1N1 is what type of classification?
A
antigenic–presence of absence of specific antigens
20
Q
Which is the least helpful way to classify bacteria?
A
based off of arrangements
21
Q
What are different types of metabolism of bacteria?
A
Aerobic
Facultative anaerobe
Anaerobic
22
Q
What are the options for classification of bacteria based off of ability to lyse erythrocytes?
A
hemolytic or NOT
23
Q
What are the options for classification of bacteria based off of ability to ferment sugars?
A
fermenter or NOT
24
Q
What are different ways to classify microbial pathogens in general?
A
Taxonomic (textbook)
Growth Habit
System Affected
Means of Acquisition (food borne, etc)
25
What are different examples of growth habit classification?
Extracellular
Intracellular
Toxin Producer
Pyogenic Cocci (pus former)
26
What's the deal with extracellular pathogens?
Cannot survive inside phagocytes
| Often controlled by antibody
27
What's the deal with intracellular pathogens?
Grows inside phagocytes
| Often controlled by T-cell based immunity
28
Differences from mammalian cells provide targets for antimicrobial agents
Give examples of these differences that can be targeted.
```
Cell wall
Cytoplasm
Nucleic acid synthesis
Protein synthesis
Metabolic pathways
```
29
Give examples of bacterial structure giving rise to pathogenesis.
Sometimes their structures can cause these things...
Inflammation
Resistance to host factors
Adherence to cells and tissues
30
What is the structure of a bacterial chromosome?
Single double-stranded circle
| No nucleus or nuclear membrane
31
Bacteria have plasmids. What are these? What info do they carry?
Small, extra chromosomal DNA
| May encode extra, non-essential functions, e.g., toxins or antibiotic resistance
32
Streptococci & diplococci have what arrangement?
chains-single division plane
33
staphylococci have what arrangement?
clump-multiple division plane
34
What are some examples of toxin producers?
tetanus & botulinim--symptoms at distant sites
35
How does the bacterial ribosome differ from the human ribosome?
Human: 80S
Bacterial: 30S + 50S-->70S
different proteins than eukaryotes have.
36
Describe the cytoplasmic membrane of a bacteria?
there aren't any sterols, like cholesterol
37
What is the exception to the rule that bacteria don't have sterols in their membranes?
mycoplasma
| they actually have cholesterol b/c as they move around they pick up stuff from other people's membranes.
38
Is staph aureus gram positive or negative?
gram positive
39
What is the peptidoglycan layer for bacteria? Which types of bacteria have it?
this is the cell wall of bacteria.
All types have it.
Gram negative: it is thinner & is sandwiched b/w the outer membrane & inner membrane.
Gram positive: it is thick & right outside the inner membrane
40
What is periplasm? Which type of bacteria exhibit this?
this is the space b/w the inner membrane & peptidoglycan thin cell wall of gram negative bacteria. Enzymes etc are found there.
41
What is the repeating disaccharide that makes up the peptidoglycan cell wall?
NAG-NAM
| **the poly AA chain is attached to NAM
42
What is NAG?
N-acetyl glucosamine
43
What is NAM?
N-acetyl muramic acid
44
What is the stem peptide of the peptidoglycan cell wall?
4 AA that are attached to NAM.
Alanine-Glucose-Lysine-Alanine
**w/ 2 alanines at the end. I think one gets chopped off with cross linking
45
Stem peptides are linked with a transpeptide bridge composed of ______. This is accomplished by which enzyme?
glycine (pentaglycine)
**transpeptidases; also D-alanine carboxypeptidases
aka penicillin binding proteins b/c they are the target of antibiotics.
**lysine on one (3rd residue) is attached to the alanine (4th residue) of the other
46
What is the purpose of the peptidoglycan cell wall?
to give a rigid & protective structure to the bacteria.
| to resist osmotic pressure
47
Describe the process of peptidoglycan biosynthesis.
1. form the precursor in the cytoplasm (water soluble)
2. attach the precursor to the inside of the membrane
3. flip the precursor to the other side of the membrane
4. attach precursor to disaccharide chain & cross link the AA chains. Form a strong matrix!!
48
Does NAM or NAG have a lactyl group?
NAM
49
What is the role of bactoprenol-phosphate in peptidoglycan synthesis?
it carries precursors across the membrane to become a part of the cell wall
50
How do beta lactam antibiotics target bacterial cell walls?
they bind the transpeptidases & prevent cross linking.
then the bacteria burst under the osmotic pressure
**vancomycin also has a way of targeting this step (but not a beta lactam antibiotic)
51
Which part of peptidoglycan biosynthesis involves transglycosylation?
transglycosylation: linking together the disaccharide units into a linear polymer (NAG & NAM)
52
Which part of peptidoglycan biosynthesis involves transpeptidation?
transpeptidation: linking together the polyAA chains. cross linking!
53
Describe the process involved in a gram stain.
1. use heat or alcohol to fix cells onto the slide
2. use crystal violet to stain the cell wall
3. gram's iodine
4. Decolorizer (alcohol or acetone)
5. safranin
54
What is the purpose of the gram's iodine?
it precipitates the crystal violet into the gram positive cell wall
55
Gram positive bacteria appear how during the gram stain?
they appear colorless before the crystal violet & then they appear blue/purple the rest of the time.
56
Gram negative bacteria appear how throughout the gram stain?
They appear blue during the crystal violet & gram's iodine steps. After the decolorizer they are colorless. Then, they are RED after the safranin.
57
What does this mean: I'm positively blue over you.
Gram positive bacteria=blue.
| Then you know--gram negative is red.
58
T/F Sometimes a gram negative bacteria will stain gram positive--blue.
False. It never will. The decolorizer will always take away the blue.
59
T/F Sometimes a gram positive bacteria will stain gram negative-red.
True. B/c the gram positive cell wall can become compromised.
60
What are some of the factors that can compromise the gram positive cell wall & cause it to stain gram negative?
penicillin & other antibiotics that affect a cell wall
old age-autolytic enzymes
too much heat fixation
61
Why is it advised (unless there is an emergency) to take a sample of the bacteria infecting a patient before administering antibiotics?
b/c if you are going to do a gram stain & you have already given penicillin or something--you could think you have gram negative bacteria when you really have gram positive.
62
Once again, describe the cell wall of gram positive bacteria.
thick, multilayered
mainly made up of peptidoglycan
the cell wall surrounds the cytoplasmic membrane
contains teichoic & lipoteichoic acids
63
What degrades the cell wall of gram positive bacteria? What results from this degradation?
lysozyme (found in tears)
| results in protoplasts
64
What are protoplasts?
this is what results from a gram positive bacteria losing its cell wall entirely. You are left with intracellular contents
65
What are the 2 types of teichoic acids?
Teichoic acid
| Lipoteichoic acid
66
What is the structure of teichoic acid? How is it found?
polymer of polyol phosphates
| linked covalently to the peptidoglycan of the cell wall
67
What is the function of teichoic acid?
affects virulence (increases i think)
68
What is the structure of lipoteichoic acid? How is it found?
structure of teichoic acid (polymer of polyol phosphates) + fatty acid
it is anchored in the cytoplasmic membrane
69
What is the function of lipoteichoic acid?
Stimulate innate host responses in manner similar to endotoxin of gram negative bacteria
**has proinflammatory properties
70
What is the endotoxin we are talking about found in gram negative bacteria?
lipopolysaccharide
71
Describe the structure of the gram negative cell wall.
cytoplasmic membrane
outside of that is a thin cell wall
then an outer membrane (not found in gram positive)
72
What is found in the peptidoglycan layer of gram negative bacteria?
so...similar peptidoglycan structure with cross linking etc. It is just thinner than the cell wall of gram +. Also, it doesn't have teichoic acids.
It is separated from the cytoplasmic membrane by a periplasmic space (not found in gram +).
73
Describe the structure of the outer membrane of gram negative bacteria.
inner layer: normal phospholipid layer
| outer layer: mainly lipopolysaccharide endotoxin
74
How do things get thru this crazy outer membrane of the gram negative bacteria?
there are porins present that allow small cytophilic particles (<700Da) to get thru.
75
Which attackers work on gram negative bacteria? Which don't?
Don't Work: lysozyme!; hydrophobic or large antibiotics
| Work: small & cytophilic to get thru the porin.
76
Lipolpolysaccharide (LPS) found in the outer membrane of gram negative bacteria is highly toxic & is shed into the body during infection. What are its 3 components?
Lipid A
Core polysaccharide
O antigen
77
What's the deal with Lipid A?
this is what is responsible for the endotoxin activity
| **it is bound to the core polysaccharide
78
What's the deal with the core polysaccharide of LPS?
It is 9-12 sugars.
| it includes an unusual sugar: 2-keto-3-deoxy-octanoate (KDO)
79
Which antibiotic binds Lipid A of LPS?
polymyxin B
80
Describe the O antigen that is attached to LPS. What is an example of gram negative bacteria that lack this O antigen?
50-100 repeating units of 4-7 sugars
* *a means of classifying bacteria
* *Neisseria produce LOS (lipooligosaccharide--LPS minus the O antigen).
81
Which have a cell wall? Outer membrane? LPS? Teichoic acids? Gram negative/Gram positive
Gram Negative--thin cell wall; outer membrane present; LPS present; teichoic acids absent
Gram Positive--thick cell wall; outer membrane absent; LPS absent; teichoic acids present
82
Which have spores? Capsules?
| Gram negative/Gram positive
Gram negative--no spores; sometimes have a capsule
| Gram positive-some spores; sometimes have a capsule
83
Which is sensitive to lysozyme? Penicillin sensitive? Which make exotoxins?
Gram negative/Gram positive
Gram negative--lysozyme resistant; penicillin resistant; sometimes make exotoxins
Gram positive--lysozyme sensitive; penicillin sensitive; commonly make exotoxins
84
Describe the structure of bacterial capsules.
usually composed of polysaccharides
makes the bacteria anti-phagocytic
common vaccine target (T-independent antigens)
85
What is an exception to bacterial capsules being made of polysaccharides?
Bacillus anthracis is exception – poly-glutamic acid in the capsule
86
What are the flagella that are sometimes found on bacteria? What is their fcn?
rope-like propellers
they are coiled protein subunits
fcn: provide motility
87
What are the fimbriae found on bacteria? What is their fcn?
they are hair-like structures
composed of protein subunits (pilin)
fcn: adherence factors
special fcn: F-pili (sex pili) used to transfer bacterial chromosomes between cells
88
There are bunch of reasons why mycobacterial cell walls (including mycobacterium tuberculosis) are different. What are the differences?
```
peptidoglycan (intertwined w/ arabinogalactan)
cell wall also has...
wax like lipid coat w/ mycolic acid
cord factor
wax D
```
89
What do these differences in the mycobacterial cell wall cause? Are mycobacteria considered gram negative, positive?
these differences cause resistance to disinfectants. Ex: hard to disinfect a room of a TB patient.
Weakly gram positive. Really: acid fast
90
What does it mean to be acid fast?
these bacteria are resistant to the decolorizing procedure in gram staining
often use Ziehl-Neesen stain
91
What's the deal with mycoplasma? What are they resistant to?
they lack a peptidoglycan layer
resistant to penicillins or beta lactam antibiotics b/c of this lack of cell wall
**they incorporate their host sterols into their membranes--like cholesterol.
92
What is the function of spores? Which types of bacteria make them?
Fcn-allows bacteria to survive harsh environments
Gram positive (never negative) make them!
This includes clostridium & bacillus
93
Clostridium is an anaerobe that causes _____.
tetanus
94
Bacillus can cause what?
one form can cause anthrax
| one form can cause food poisoning
95
What triggers sporulation?
depletion of nutrients, harsh environments
96
What triggers germination?
some form of stressor, water and a triggering nutrient
97
What are the contents of spores?
Complete copy of chromosome
Minimal proteins and ribosomes
High concentration of dipicolinic acid (unique to spores) bound to Ca++
98
What are some of the nutritional requirements for bacterial growth?
```
Carbon
Nitrogen
Growth factors, e.g., B complex vitamins
Inorganic ions
Oxygen
```
99
Oxidation reduction potential is important for bacteria to grow b/c of _____.
the electron transport chain!
100
Bacteria have certain preferences--conditions where they grow best. Give examples of these preferences.
certain temps
certain osmotic conditions
certain pHs
101
What do you call bacteria that thrive at low temps (-5--30dC)? (10-45dC)? 25-80dC?
```
Low Temp (-5-30dC): psychrophilic
Medium Temp (10-45dC): Mesophilic
High Temp (25-80dC): thermophilic
```
102
What are the 3 forms of energy production? List them from most efficient to least efficient.
```
Most Efficient
1. Aerobic Respiration
2. Anaerobic Respiration
3. Fermentation
Least Efficient
```
103
What's the deal with aerobic respiration?
oxygen is used as the terminal electron acceptor
104
What's the deal with anaerobic respiration?
inorganic compounds are used as the terminal electron acceptors
**like nitrate, sulfate, carbonate
105
What's the deal with fermentation?
organic molecule is used as the final electron acceptor
not very efficient
a last resort for bacteria
106
What's the deal with obligate aerobes?
they can only use O2
produce H2O2 & superoxide radicals which are toxic to them so they also produce superoxide dismutase & catalase to deal with this problem.
107
What's the deal with facultatively anaerobic bacteria?
they prefer O2 as the electron acceptor but if it's not there no big deal--they'll use something else. Maybe fermentation.
108
What's the deal with obligate anaerobes?
oxygen is actually toxic to these guys
inorganic compounds are the terminal electron acceptor
**don't use fermentation.
109
If obligate aerobes aren't using their enzymes...what's another way for them to get rid of their superoxide radicals etc?
by pumping them out of the cell!
110
What are 2 ways to determine bacterial mass?
dry weight
| turbidity-measure optical density
111
What are different ways to determine cell number?
direct counting by microscopy
| quantitative culture
112
What are the steps involved in quantitative cultures?
Prepare serial dilutions
Culture in petri plates
Directly count colonies
113
What are the different parts of the bacterial growth curve?
lag phase
exponential growth
stationary phase
death or decline
114
What happens during the lag phase of the bacterial growth curve?
Increase in cell size
Little or no cell division
adjustment to the new environment
115
What happens during the exponential growth phase of the bacterial growth curve?
Cell number and mass increase simultaneously
Growth rate expressed by natural exponential function (doubling time)
Growth rate depends on bacterial species and environment
**as it runs out of nutrients or accumulates radicals--it hits the stationary phase.
116
```
Bacteria may differ greatly in the efficiency of their energy production. Which of the following terminal electron acceptors is on a pathway that would maximize total ATP production?
A) Nitrate
B) Sulfate
C) Oxygen
D) Acetyl CoA
E) Pyruvic acid
```
C. Oxygen
117
```
Transpeptidases are targets of the beta lactam class of antibiotics. What is the function of transpeptidases in cell wall synthesis?
A) Catalyze formation of the pentapeptide that is attached to N-acetyl muramic acid
B) Catalyze formation of the N-acetyl glucosamine – N-acetyl muramic acid disaccharide transglycosylase
C) Cross-link a N-acetyl glucosamine – N-acetyl muramic acid disaccharide to a growing polysaccharide chain--transglycosylase
D) Generate cross-linking between the peptides on peptidoglycan to produce a complex matrix
E) Facilitate re-incorporation of lipid carriers into the lipid carrier pool
```
D!! It connects the peptides.
Transpeptidases are also called penicillin binding proteins. they both affect the vancomycin & penicillin actions.
118
Porins have been identified as potential vaccine targets for Neisseria meningitidis and Neisseria gonorrhoeae. What is the location of porins in the bacterial cell wall?
A) The outer membrane of gram positive bacteria
B) The outer membrane of gram-negative bacteria
C) Peptidoglycan of the gram-positive cell wall
D) Peptidoglycan of the gram-negative cell wall
E) Cytoplasmic membrane
B!!
