Microbiology Flashcards
(194 cards)
0
Q
Name the three types of bacteria?
A
Round (coccus)
Rod-like (bacillus)
Spiral
1
Q
What is the difference between prokaryotes and eukaryotes?
A
Little organisation
Much smaller
2
Q
What do cocci and bacilli often grow in?
A
Doublets (diplococci) or chains (streptococci), but cocci that grow on clusters are called staphylococci
3
Q
Some bacteria species are pleomorphic , what is pleomorphic?
A
Pleomorphic is the ability of bacteria to change their shape or size in environmental conditions
4
Q
What could affects a bacterias shape?
A
Antibiotics (e.g. Penicillin) that affect cell wall biosynthesis
5
Q
What are the fundamental traits that most prokaryotes share?
A
Thick,complex outer envelope
Compact genome
Tightly coordinated cell functions
6
Q
What is the cytoplasm?
A
Consists of a gel-like network
7
Q
What is the cell membrane?
A
Encloses the cytoplasm
8
Q
What is the cell wall?
A
Covers the cell membrane
9
Q
What is the nucleoid?
A
A non-membrane bound area of the cytoplasm that contains the chromosome in the form of looped coils
10
Q
What is the flagellum?
A
External helical filament whose rotary motor propels the cells
11
Q
What are common chemical components all cells share?
A
Water
Essential ions
Small organic molecules
Macromolecules
12
Q
How do we study cell parts?
A
Subcellular fractionation
Structural analysis
Genetic analysis
13
Q
What techniques are used to break up cell but allow subcellular parts to remain intact?
A
Mild detergent analysis
Sonication
Enzymes
Mechanical disruption
14
Q
What does infection refer to?
A
The relationship between the host and microbe and the competition for supremacy between them
15
Q
What is disease?
A
Any change fork the general state of good health
16
Q
What are microbiota?
A
Microbes that reside in the body without causing disease
17
Q
What is mutualise?
A
When both host and microbe benefits
18
Q
What is communalism?
A
The microbe benefits and the host is unaffected
19
Q
What is parasitism?
A
Pathogens cause damage and disease in the host
20
Q
What is pathogenicity?
A
A microbes ability to enter a host and cause disease
21
Q
What is virulence?
A
Is the degree of pathogenicity
22
Q
What are pathogenicity islands?
A
Refers to gene clusters responsible for virulence
23
Q
When does a exogenous infection occur?
A
If a pathogen breaches the host external defense and enters sterile tissue
24
When does an endogenous infection occur?
If normal microbiota enter sterile tissue
25
When do opportunistic infections occur?
When commensals take advantage of a change in the body's environment that favours the microbe
26
What does primary infection occur in?
Healthy bodies
27
What does secondary infections occur in?
In a weakened by a primary infection
28
What are local diseases?
Restricted to a single area
29
What do systemic disease disseminate to?
Organs and systems
30
What is the incubation period?
Time between entry of the microbe and symptom appearance
31
What is the prodromal phase?
The time of mild signs of symptoms
32
What is the acme period (climax)?
Is when signs and symptoms are most intense
33
What is the period of decline?
As signs and symptoms subside
34
What is the period of convalescence?
When the body returns to normal
35
What are acute diseases?
Develop rapidly, cause severe symptoms, and fade quickly
36
What are chronic disease?
linger for long periods of time and are slower to develop and recede
37
What does pathogens entry into the host depend on?
Cell adhesion and the infectious dose
38
What is the portal of entry?
Is the route an exogenous pathogen uses to enter the body
39
What is the infectious dose?
The number of microbes entering the body
40
What do adhesions on pathogens allow?
Pathogens have adhesions that allow them to adhere to specific tissue
41
What is invasiveness?
The ability of a pathogen to penetrate tissues and spread
42
What mechanism do many pathogens use to enter cell or pass through defences?
phagocytosis
43
What does staphylococci produce?
Coagulate to form a blood clot that protects them phagocytosis
44
What does streptokinase allow bacteria to do?
Dissolve fibrin clots and allows dissemination of the bacteria
45
What does hyaluronidase do?
Enhances pathogens penetration through tissues
46
What do leukocidins do?
Disintegrate neutrophils and macrophages
47
What do hemolysins do?
dissolve red blood cells
48
Why can virulence be enhanced in biofilms?
Because immune cells cannot reach bacterial cells
49
What is toxigenicity?
The ability of pathogens to produce toxins
50
What is toxaemia?
The presence of toxins in the blood
51
What are exotoxins?
Are proteins produced during bacterial metabolism
52
What do neurotoxins act on?
The nervous system
53
What do enterotoxins act on?
The gastrointestinal tract
54
What do antitoxins do?
They are produced by the host body and neutralize toxins
55
What are toxoids and toxins?
Toxicity been destroyed but still elicit an immune response
56
When are endotoxins released?
Upon disintegration of gram-negative cells
57
What do endotoxins cause?
Blood coagulation
| Endotoxins shock may occur with antibiotic treatment of diseases caused by gram-negative bacilli
58
What do epidemiologist do?
Identify the reservoir of an infectious disease
59
What are reservoirs?
Places in the environment where a pathogen can be found
60
What are carriers?
Recovered from the disease but continue to shed the disease agents
61
What are communicable diseases?
contagious
62
What are noncommunicable diseases?
Not easily transmitted to another host bunt they acquire directly from the enviromnent
63
What is a endemic disease?
Is a habitually present at a low level in a certain geographic area
64
What is a epidemic disease?
Occurs in a region in excess of what is normally found in that population
65
What is a outbreak?
A more contained epidemic
66
What is a pandemic?
A worldwide epidemic
67
What are nosocomical infections?
Serious health threats within the health care system and occur as a result of chains of transmission in hospitals
68
What are health care-associated infections (HALs)?
Occur as a result of receiving treatment for another condition
69
What does globalization mean?
Diseases emerging anywhere in the world that can spread globally
70
What are zoonoses?
Diseases transmitted from others vertebrate animals to humans
71
Give four reasons why a disease may re-emerge?
Poor population health
pathogen evolution
International travel
Climate change
72
What is Ankeny tool for sub-cellular fractionation?
ultracentricfuge
73
What does the ultracentrifuge do?
High rotation rate produces centrifugal forces strong enough to separate particles by size
74
What does x-ray diffraction crystallography show?
The 3D-form of cell components at atomic level.
| Helps relate structure to function.
75
What does the cell wall do?
Confers the shape and rigidity to the cell and helps it withstand turgor pressure
76
What does the bacterial cell wall or the sacculus consist of?
A single interlinked molecule
77
What are most bacterial cell wall made up of?
peptidoglycan (or murein)
78
What does peptidoglycan consist of?
Long polymer of two disaccharides called N-acetylglucosamine [NAG] and N-acetylmuramic acid [NAM], bound to a peptide of 4-6 amino acids
79
What can the peptide cross-bridges of peptidoglycan connect?
glycan strands
80
What is peptidoglycan the site of action for?
Some antibiotics such as penicillin and the cephalosporins
81
What percentage of peptidoglycan is in gram-positive bacteria?
50%
82
What percentage of bacteria is in gram-negative bacteria?
2-10%
83
What type of cell wall does gram-positive bacteria have?
Thick cell wall
| E.g. staphylococcus
84
What type of cell wall does gram-negative bacteria have?
thin cell wall
| E.g. pseudomonas
85
What does gram-positive bacteria contain?
```
capsule- made of polysaccharides
S-Layer-made of protein
Thick cell wall- amino-acid cross-links in peptidoglycan
Tectonic acids for strength
Plasma membrane
```
86
What does a gram-negative bacteria contain?
thin peptidoglycan layer consists of one or two sheets.
| Covered by an outer membrane, which confers defensive abilities and toxigenic properties on many pathogens
87
What is teichoic acid (gram+)?
Water-soluble polymers containing a ribitol or glycerol residue linked by phosphodiester bonds
88
What is teichoic acid chemically boned to?
peptidoglycan
89
What is lipoteichoic acid chemically bonded to?
glycolipid
90
What is the function of teichoic acid?
Bacterial surface antigenic determinants, and lipoteichoic acid helps anchor the wall to the membrane
91
What may account for half of the dry weight of a gram-positive cell wall?
teichoic acid
92
Where is periplasmic space found?
Gram-negative cells
93
What is the periplasmic space?
The area between the outer membrane and cell membrane
94
What does the periplasmic space contain?
Hydrated peptidoglycan, hydrolysis enzymes including beta-lactamases, specific carrier molecules, and oligosaccharides
95
What does the cell membrane act as?
semipermeable barrier
96
What are the reinforcing agents in eukaryotic membranes?
Sterols such as cholesterol
97
What are the reinforcing agents in bacteria membrane?
hopanoids or hopanes
98
What cell is the outer membrane found?
gram-negative
99
What is the outer membrane?
Is a phospholipids bilayer in which the phospholipids of the outer portion are replaced by lipopolysaccharides.
100
What does outer membrane contain?
Embedded proteins
Transport proteins
Some monopole proteins(phospoholipases and proteases)
101
What is the function of outer membrane?
Protects cells from harmful enzymes and some antibiotics
| Prevents leakage of periplasmic
102
What is LPS?
lipopolysaccharide found in the outer fold of the OM of gram-negative cells
103
What does LPS contain?
Lipid A, several long-chain fatty acids attached to phosphorylated glucosamine disaccharide units, and a polysaccharide composed of core and terminal repeating units
104
What charge is LPS?
-ve charged and noncovalently cross-bridged by divalent cations
105
What is the function of LPS?
1. LPS is also termed endotoxins; the toxity of LPS is associated with the lipid A.
2. Contains surface antigenic determinants, including Oantigen found in the polysaccharide compnent
106
What does the nucleus consist of?
Polyamide and magnesium ions which are bound to -ve charged, circular, supercoiled, double-stranded DNA; small amounts of RNA; RNA polymerase and other proteins
107
What does the bacterial cytoplasm contain?
Ribosomes and granules
108
What does the bacterial cytoplasm not contain?
Not contain organelles
109
What sizes are the subunits of a prokaryotic ribosomes?
30s and 50
110
What are pile?
pili are rigid surface appendages composed mainly of a protein called pilin
111
What are ordinary pile?
Adhesions are involved in bacterial adherence and gram-positive cell conjugation
112
What are sex pile?
Involved in attachment of donor and recipient bacteria in gram-negative cell conjugation
113
What properties may ordinary pile show?
antiphagocytic properties
114
How does prokaryotes synthesis of RNA and proteins difgfer from eukaryotes?
Prokaryotes synthesize RNA and proteins continually whilst the cells DNA undergoes replication
115
What does bacterial growth refer to?
An increase in bacterial cell numbers from bacterial reproduction due to binary fission
116
What is generation time?
Average time required for cell numbers to double. The interval of time between successive binary fissions
117
What may generation time be determined by?
Measuring cell concentration or biomass density
118
What does asynchronously mean?
All cells do not divide at precisely the same moment
119
What does bacterial cultivation refer to?
The propagation of bacteria based on their specific pH, gaseous, and temperature prefrerences
120
What does a bacterial cultivation environment require?
```
A carbon source
A nitrogen source
Energy sourceinorganic salts
Growth salts
Growth factors
Electron condor and acceptors
```
121
What is a heterotroph?
require preformed organic compounds (e.g. sugar, amino acids) for growth
122
What is a autograph?
Does not require preformed organic compounds for growth because they can synthesise them from inorganic compounds and carbon dioxide
123
What are two growth medium I?
Minimal essential growth medium
| Complex growth medium
124
What are the two growth II mediums?
Differential growth medium
| Selective growth medium
125
What is minimal essential growth medium?
Contains only the primary precursors compounds essential for growth
Slow generation time
126
What is complex growth medium?
Medium contains most organic compunds
127
What is differential growth medium?
Medium contains a combination of nutrients and pH indicators to allow visual distinction of bacteria that grow on or in it to see species that lack biochemical processes
Colonies have distinctive color
128
What is selective growth medium?
Medium contains compounds that prevent the growth of some bacteria while allowing the growth of other bacteria
Dyes or sugars, high salt concentration, or pH are used to achieve selectivity
129
What do fastidious organisms require?
An enriched medium containing specific nutrients
130
How to bacterial and archaeal cells reproduce?
asexually
131
What does a shorter doubling time of a pathogen mean?
Means a shorter incubation period of disease
132
How many faces of bacterial growth?
4 phases
133
What is the lag phase?
Where no cell division occurs while bacteria adapt to their new environment
134
What is the log phase?
Exponential growth of the population, where human disease symptoms usually develop
135
What is the stationary phase?
When reproductive and death rates equalize
136
What is the decline phase?
When the accumulation of waste products and scarcity of resources causes the population to enter the decline/ exponential death phase
137
What are endospores a response to?
nutrient limitation
138
What are endoscopes?
Highly resistant structure formed by species of Bacillus and Clostridum when nutrient supplies are low
139
What does a stressed cell undergo?
Asymmetrical cell division creating a small perspore and larger mother cell
140
What do prespores contain?
Cytoplasm, DNA and dipicolinic acid which stabilized proteins and DNA
141
What does the mother cell do?
Matures the perspore into an endoscope then disintegrates freeing the spore
142
What are endospores resistant to?
Desiccation and heat
143
What happens when environmental conditions are favourable again?
Protective layer break down and the spore germinates into a vegetative cell
144
What length are most bacterial and archaeal cells?
1-5 micrometres in length
145
What do negative stain technique use?
Acidic dyes which are repelled by cell wall, leaving clear cells on a dark background
146
What is a gram strain?
Cells stained with crystal violet and gram iodine solution and washed with a decolourized. safranin is applied as a counter stain
147
How can you differentiate between grame +ve and -ve bacteria using gram stain?
Gram +ve bacteria retain the crystal violet whereas gram -ve bacteria do not it has the orange-red colour of the safranin
148
What are psychrophiles?
Make up the largest portion of prokaryotes in earth. How optimally below 15oC
149
What temperature do mesophiles thrive at?
10-45oC including pathogens that thrive in the human body
150
What temperature do thermophiles multiply best at?
60oC, living in compost heaps and hot springs
151
What temperature do hyperthermophiles grow at?
Above 80oC, found in seafood hot-water vents
152
What are aerotolerant species insensitive to?
oxygen
153
What are obligate anaerobes inhibited or killed by?
oxygen
154
What do facultative prokaryotes grow with?
Oxygen or in reduced oxygen envrionments
155
What are pure culture?
A population consisting of only one species of prokaryotes. Population measurements are made using pure cultures
156
What does pour-plate isolation method allow?
Separation of species through dilution of a sample
157
What does streak-plate isolation method do?
Spreads out individual cells to form discrete colonies of species
158
How can the turbidity (cloudiness) of a sample be measured?
By a spectrophotometer
159
What do colonies grow on in a standard plate count procedure?
Diluted broth
160
What does the number of colonies in the broth indicate?
The original number of viable (living) cells
161
What is sterility?
Total absence of viable microorganisms as assessed by no growth on any medium
162
What is bactericidal?
Kills bacteria
163
What is bacteriostatic?
Inhibits growth of bacteria
164
What is sterilization?
Removal or killing of all microorganisms
165
What is disinfection?
Removal or killing of disease-causing microorganisms
166
What is sepsis?
infection
167
What is aseptic?
Without infection
168
What is antiseptic?
Any procedure that inhibits the growth and multiplication of microorganisms
169
What are antibiotics?
Compounds produced by one microbe that adversely affect other microbes
170
What is a penicillin?
A antibiotic that is a mild that inhibited the growth of Staphylococcus aureus colonies on a plate
171
What are sulfa drugs?
Analogy of PABA a precursors of a vitamin needed for DNA synthesis. Inactive until converted by the body to active agents
172
What is streptomycin?
Antibiotic produced by an actinomycete bacterium found in the soil
173
What does chloramphenicol interfere with?
Ribosomes at high levels interferes with red blood cell development
174
What does broad-spectrum mean?
Effective against many species
175
What does narrow-spectrum mean?
Effective against few or a single species
176
Why may a antibiotic be modified?
Increase efficacy
| decrease toxicity to humans
177
What do many antibiotics only affect?
Growing cells such as inhibitors of cell wall synthesis- only effective if organism is building new cell wall e.g.penicillin
178
What do bactericidal antibiotics do?
Kill target organisms
179
What do bacteriostatic antibiotics do?
Prevent growth of organisms- cannot kill organism, immune system removes infection
180
What is antimicrobial chemotherapy based on?
principle of selective toxicity- that compound/drug is harmful to a microorganism but not harmful to its host
181
What are properties of drugs in antimicrobial therapy?
```
antimetabolites
Inhibitors of cell wall biosynthesis
Inhibitors of protein synthesis
Inhibitors of nucleic acid synthesis
Can alter or inhibit cell membrane permeability or transport
```
182
What two classes can antimicrobial drugs be?
bacteriostatic or bactericidal
183
What is the test use of drugs in antimicrobial therapy?
Synergistic combinations of bacteriostatic drugs
184
What is used to determine antimicrobial activity?
Dilution or diffusion test the activity is measured by determining the minimal inhibitory concentration
185
What can alter antimicrobial activity?
```
drug stability
PH
Microbial environment
Number of microorganisms present
Length of incubation with drug
metabolic activity of microorganisms
```
186
What could genetic or nongenetic drug resistance modify?
Antimicrobial activity of a drug for a specific bacterium
187
What is the minimal inhibitory concentration?
The lowest concentration that prevents growth it varies for different bacterial species
188
How is the minimal inhibitory concentration tested?
By diluting the antibiotic
189
When the minimal inhibitory concentration is reached what can it still contain?
Living (but non-growing) organism
190
What is the minimal lethal concentration?
The least amount of drug that can produce death.
| No colonies
191
What do hyaluronidase do?
Enhance pathogen penetration through tissues
192
What do leukocidins do?
disintegrate neutrophils and macrophages
193
What do hemolysins do?
Dissolve re blood cells
