LSCI 230 Midterm 1 Flashcards
1
Q
True or false: the science of microbiology existed before the invention of microscopes
A
False
2
Q
Who invented the microscope?
A
Antoni Van Leeuwenhoek
3
Q
What did van Leeuwenhoek call microorganisms?
A
animalcules
4
Q
What is the miasma theory?
A
smell causes sickness
5
Q
What is spontaneous generation?
A
Hypothesis that some vital force can create living organisms from inanimate objects (Middle Ages to late 19c)
6
Q
How did Francesco Redi disprove spontaneous generation?
A
Mid 1600s: Francesco Redi demonstrated that maggots did not develop from meat
if the meat was protected by a fine gauze cover.
7
Q
What century was Pasteur?
A
19 th
8
Q
Who proposed to wash hands with chlorine solution?
A
Ignaz Semmelweis 1847
9
Q
Who proposed to sterilize medical devices in phenol
A
Joseph Lister 1867
10
Q
Who proved that tuberculosis was caused by a bacterium, Mycobacterium tuberculosis ?
A
Robert Koch 1877
11
Q
What did Pasteur’s experiment also show?
A
That microorganisms were present in the air, a possible source of infection
12
Q
What did Pasteur’s experiment lead to?
A
Development of effective sterilization procedures and pasteurization
13
Q
Who wrote diagnostic bactériologique?
A
DR. Trouessart (1896)
14
Q
True or False: Colony morphology is an exact science
A
False
15
Q
What is a morphotype?
A
Colony with specific characteristics
16
Q
What are colony characteristics influenced by?
A
Medium and incubation conditions
17
Q
Name two general functions of cells?
A
Genetic function
Catalytic function
18
Q
Name 3 properties of all cells
A
Metabolism
growth
evolution
19
Q
Name properties of some cells
A
motility
differentiation
formation of biofilm
virulence
20
Q
Name 3 functions of the membrane
A
permeability barrier
protein anchor
energy conservation
21
Q
What is the lipid bilayer stabilized by in eukarya?
A
sterol
22
Q
Name the components of sterol
A
polar head
rigid planar steroid ring structure
nonpolar hydrocarbon tail
23
Q
Name three types of sterols
A
cholesterol
ergosterol
stigmasterol
24
Q
Are sterols abundant in bacteria and archaea?
A
no
25
What is the membrane stabilized by in bacteria?
hopanoids
26
What dictates the size of a cell?
the ability to transport at the surface
27
How is DNA stored in bacteria and archaea?
circular molecule, double stranded
28
what is the ploidy level of bacteria and archaea?
haploid
29
How is DNA stored in eukarya?
linear molecules, double stranded
30
What is the ploidy level of eukarya?
diploid
31
What is the ribosome composed of?
Ribosomal RNA and proteins
32
What is the function of ribosomes?
translates mRNA into amino acid chains to form proteins.
33
Where do we find ribosomes in prokaryotes?
free in cytoplasm or attached to cytoplasmic membrane
34
Where do we find ribosomes in eukaryotes?
free in the cytoplasm or bound to the ER
35
What ribosome subunits do prokaryotes have?
30S+ 50S = 70S
36
What ribosome subunits do eukaryotes have?
40S + 60S = 80S
37
What is the Svedberg unit?
Describes the rate of sedimentation of a particle in an ultracentrifuge. Proportional
to the size, shape and density of the particle but the relationship is not linear
.
38
what kind of cells do cell walls surround?
Plants, algae, fungi
39
Is cell wall present in animal cells?
no
40
What is the function of the cell wall?
protect the cell and give shape
41
What is the main polysaccharide component of cell walls in plants, algae ?
cellulose
42
What is the main polysaccharide component of cell walls in fungi?
Chitin
43
What is euchromatin?
Loosely packed, actively transcribed
44
What is heterochromatin?
densely packed, low level of transcription
45
What is the ER?
a system of membranous channels
46
What is the ER membrane composed of?
bilayer of phospholipid
47
Name two characteristics of the rough ER
studded with ribosomes, important for protein synthesis
48
Name two characteristics of smooth ER
no ribosomes, involved in synthesis of lipids
49
What is the ER also involved in?
protein modification
50
What are endosomes and vesicles?
intracellular membrane-enclosed
compartment. They can fuse with other membrane. When two vesicles
fuse together, their respective content is merged
51
What are lysosomes?
vesicles that contains hydrolytic enzymes required for
degradation of materials brought in by phagocytosis and endocytosis via
the formation of phagosome or endocytic vesicles
52
What is the golgi body?
set of membrane compartments involved in further
processing of proteins and their distribution
53
How can proteins be secreted outside the cell?
by secretory vesicles
54
What characterises the outer membrane of mitochondria?
many porin proteins ( permeable to small molecules)
55
What is the inner membrane of mitochondria composed of ?
proteins and lipids
56
What is the mitochondrial matrix composed of?
Enzymes, circular DNA and ribosomes(70S)
57
True or false: mitochondria can synthesize some of their own proteins
True
58
What important role does the mitochondria have?
produces most of the ATP required by the cells
59
What characterizes the outer membrane of chloroplast?
porins, similar to mitochondria
60
What characterizes the inner membrane of chloroplast?
transport proteins
61
What are thylakoids?
closed system of interconnecting sacks and tubules
62
Describe the stroma
circular DNA, 70S ribosomes, enzymes of the calvin cycle
63
Are chloroplasts able to synthesize their own protein?
Yes, some of them and the rest is imported from the cytoplasm
64
What do thylakoids contain?
enzymes and pigments that harvest light energy and the membrane
bound ATPases that use this energy to produce ATP.
65
What is the eukaryotic cytoskeleton?
a complex network of protein filaments that helps organize the
cytoplasm and give the cell its shape
66
What are microtubules?
hollow structures composed of polymerized tubulin dimers
67
What is the role of a microtubule?
“highways” for the transport of organelles and vesicles around
the cytoplasm.
68
Which two proteins attach organelles and vesicles to microtubules?
Kinesin and dynein
69
What is the role of centrioles and basal bodies?
Act as organizing centers for other
microtubule arrays.
70
What are centrioles composed of?
one complete
microtubule and two partial microtubules (triplets)
71
What are basal bodies?
centrioles that have
migrated near the cytoplasmic membrane
72
What is a centrosome?
two centrioles positioned at right angles to each other
73
What are cilia and flagella in eukaryotes made of?
9 sets of microtubule doublets
74
What are cilia and flagella covered by?
plasma membrane
75
Name 6 different shapes of bacteria and archaea
coccus
bacillus
vibrio
coccobacillus
spirillum
spirochete
76
What is the function of cell wall in bacteria?
allows the bacteria to withstand the intracellular osmotic pressure and is responsible for the shape and rigidity of the bacteria.
77
True or false: some bacteria don't have a cell wall
True
78
Name the 4 steps of gram stain
crystal violet
iodine
alcohol
safranin
79
What is the main difference between gram positive and negative bacteria?
Gram-positive bacteria have a larger peptidoglycan layer and no outer membrane
80
Name the subunits of peptidoglycan in bacteria
2 sugars: NAG and NAM
Short peptide side chain containing unusual amino acids
81
What part of peptidoglycan does lysosome target?
link between NAM and NAG
82
What does the polymerization of the sugar backbone provide?
rigidity to the structure in only one direction.
83
What does the bond between the the peptide chain of two adjacent peptidoglycan chains provide?
rigidity in the other direction
84
What kind of link does the gram negative peptidoglycan have?
Direct cross-linking
85
What kind of link does the Gram-positive peptidoglycan have?
Interbridge cross-linking
86
What is crosslinking called?
transpeptidation
87
How much of the cell wall is peptidoglycan in gram-positive bacteria?
90%
88
What enzyme covalently attaches wall-associated proteins to peptidoglycan in gram positive bacteria?
Sortase
89
How much of the cell wall is peptidoglycan in gram-negative bacteria?
5-10%
90
Where is the peptidoglycan located in gram-negative bacteria?
the periplasm
91
what does the periplasm contain?
a high concentration of proteins involved in diverse of functions
92
Why is the outer membrane of gram-negative bacteria and atypical lipid bilayer?
phospholipids in the inside layer,
phospholipids and lipopolysaccharides in the outside layer (LPS layer)
93
What is the role of the LPS in gram-negative bacteria?
helps protect the bacteria against a variety of substances, including
antibiotics, and against the host defense system.
94
What is the LPS?
a family of complex sugar
polymers attached to a lipid moiety known as lipid A.
95
What does lipid A do in animals?
toxic to many animals as it induce inflamation
96
what is Lipid A?
an endotoxin and it plays a major role in the pathogenesis of Gram-negative bacterial pathogens
97
Are peptidoglycan and outer membranes present in the cell wall of Archaea?
no
98
What do cell walls of Archaea consist of?
Protein, polysaccharides and or glycoproteins
99
Where is the S layer in cell walls of archaea?
additional layer on top of peptidoglycan (Gram-positive) or on top of the outer membrane (Gram-negative)
100
What is the capsule made of?
Heteropolysaccharides (Majority of bacteria)
Homopolysaccharides (Some Gram-negative)
101
What is the capsule covalently bound to?
the outer membrane or to the peptidoglycan layer.
102
What is the role of the capsule?
protects against the host defense system
103
What other surface appendages do bacteria and archaea have?
flagella and fimbriae
104
What is the role of flagella?
motility
105
What is monotrichous?
1 flagellum
106
What is lophotrichous
Many flagella originating from one end of the cell
107
what is peritrichous?
many flagella around the cell surface
108
What is the flagellum structure of gram negative bacteria?
L,P, MS, C rings
109
What is the flagellum structure of gram-positive bacteria
P, MS, C rings
110
What is taxis?
Directed movement toward or away from a gradient of chemical or physical agents.
111
What is the function of fimbriae?
involved primarily in the attachment of the microorganism to surfaces.
112
Where are fimbriae anchored in gram positive and negative?
Positive: in peptidoglycan
negative: in outer membrane
113
What are fimbriae composed of in both gram?
pillin protein
114
How are fimbriae bound in both gram?
positive: covalently linked to one another
negative: not covalently bound to one anothoer
115
How are fimbriae assembled in both gram?
positive: assembled enzymatically by sortases
negative: Accessory proteins are needed, encoded with the fimbriae pilin genes
116
What are endospores?
highly differentiated cells that are
extremely resistant to harsh
environmental conditions ( dormant stage)
117
Name the 4 layers of the endospore?
exosporium
coat
cortex
core
118
What is the exosporium made of?
proteins
119
What is the coat made of?
layers of spore-specific proteins (keratin like)
120
What is the cortex made of?
peptidoglycan
121
What is the core?
cytoplasm
122
What is the role of SASPs in endospore?
bind to DNA and help protect it against damage (UV light)
123
What dehydrates the core in endospore?
DPA and Ca2+
124
Where are energy reserves and building blocks stored in bacteria and archaea?
granules or inclusions
125
What are cell inclusions enclosed in?
single layer membrane
126
What nutrients do inclusions store?
lipid (a, b), sulfur (c), polyphosphate
127
What two groups can microorganisms be classified in according to metabolism?
oxygen requirement
Source of energy, electrons, and carbon
128
What is an anaerobe?
oxygen is not required for growth
129
What is an aerobe?
require oxygen for growth
130
What is a facultative aerobe?
oxygen is not required but enhances growth rate
131
What are possible sources of energy?
chemicals and light
132
What is an example of electron sources?
organic compounds (glucose) or inorganic compounds (H2S)
133
What are possible sources of carbon?
organic compounds (glucose) or inorganic compounds (CO2)
134
What is a heterotroph?
carbon is acquired from organic chemicals
135
What is an autotroph?
carbon is acquired from carbon dioxide
136
What is the source of carbon, energy and electrons in denitrifying bacteria?
Organic compounds
137
What are the most common terminal electron acceptors under anaerobic conditions?
nitrogen compounds
138
What is denitrification?
when No N2O and N2 gases are lost in the environment
139
Why is the loss of nitrate detrimental to agricultural processes?
Plants use nitrate as a source of nitrogen
140
What is denitrification benificial for?
sewage treatment, to remove nitrate, which can stimulate algal growth in receiving water
141
What is the terminal electron acceptor of Desulfovibrio?
Sulfate or sulfite
142
What does Desulfovibrio use as an electron donor?
organic compound (lactate) or an inorganic compound (H2)
143
what does Desulfuromonas use as a terminal electron acceptor?
Sulfur
144
What does Desulfuromonas use as electron donors?
acetate, ethanol and other organic compound
145
What compound causes rotten egg smell?
H2S
146
What is required for photosynthesis?
Light-sensitive pigments
147
What is a reaction center?
Chlorophyll or bacteriochlorophyll molecules are arranged in photocomplexes
containing other photosensitive pigments and proteins
148
Which pigments funnel the energy to the RC?
The pigments that surround the reaction center
149
what are carotenoids?
hydrophobic, light sensitive pigments firmly embedded in
the photosynthetic membrane
150
What is the role of carotenoids?
protect the system against bright light, which may lead to production of toxic forms of oxygen.
151
what is the role of phycobilin?
form complexes with proteins that are the main light harvesting systems in Cyanobacteria:
phycobilisomes.
152
Where does photosynthesis take place in plants and algae?
chloroplasts, chlorophylls are attached to the membrane of the
thylakoid
153
How is the proton motive force generated in eukaryotes?
across the thylakoid membrane
Stroma: alkaline, negative.
Intrathylakoid space: acid, positive.
154
where are three places where photosynthetic pigments are integrated?
cytoplasmic membrane
intracytoplasmic membrane
thylakoid membrane
chlorosome
155
what is cyclic phosphorylation?
no need for electron donor, electron cycles through the system. Produce pmf for ATP synthase
156
What is reducing power?
need electron donor, electrons are used to reduce NAD+ to NADH by ferredoxin.
157
What two systems un in parallel in anoxygenic photosynthesis?
1. PMF to ATP (electrons cycle)
2. Reduce NAD+, oxidize H2S
158
True or false: In purple bacteria, energy of P870* is not
enough to reduce NAD+
true
159
What are nitrifying bacteria?
Organisms that use inorganic nitrogen compounds as
electron donors
160
Does nitrification require oxygen?
yes
161
What is the final electron acceptor of nitrobacter?
O2
162
What is the role of sulfur bacteria?
Oxidize sulfur compounds
163
What do thiobacillus use as an electron acceptor?
Use O2 as an electron acceptor.
164
What are methanotrophs?
Methanotrophs are aerobes, use CH4 as a source of carbon and energy
165
What fixes carbon in eukaryotes?
enzymes in the stroma of chloroplast
166
What fixes carbon in prokaryotes?
enzymes in the cytoplasm
167
What is anabolism?
production of molecules
168
What is catabolism?
production of energy, reducing power
169
What is ΔH ?
free energy
170
What is activation energy?
energy needed to
put all molecules in a reactive state.
171
What is catalyst?
substance that lowers the
activation energy. Does not affect the free energy, affects the rate.
172
What does oxidation mean?
removal of electrons
173
What is reduction?
addition of electrons
174
name 3 basic metabolic pathways
glycolytic pathway
pentose phosphate pathway
tricarboxylic acid pathway
175
What is fermentation
organic compounds are electron donors and electron acceptors. ATP is produced by substrate
level phosphorylation.
176
What is respiration?
organic compounds are oxidized to CO2 with O2 (or substitute) as the electron acceptor. Most
of the ATP is produced by oxidative phosphorylation.
177
What is the net yield of glycolysis?
2 ATP, 2NADH
178
What is the role of the TCA cycle?
Intermediates of the TCA cycles
are used as substrate for
anabolic reactions
179
What is the net yield of the TCA cycle?
2CO2
1 GTP
3NADH
1 FADH2
180
What is the reparatory chain?
series of hydrogen and electron carriers that can undergo
oxidation-reduction
181
What is the proton motive force?
Respiration results in the generation of a transmembrane proton gradient, a potential
source of energy
182
What is pmf used for?
flagellum rotation (in bacteria),
transport across the membrane and synthesis of ATP
183
What is the role of pentose phosphate?
to generate reducing power
184
Which cycles are involved in fermentation?
glycolysis and pentose phosphate
185
Which cycles are involved in respiration?
glycolysis
TCA cycle
oxidative phosphorylation
pentose phosphate
186
Where does the pentose phosphate pathway occur in eukaryotes and prokaryotes?
cytoplasm
187
What is facilitated diffusion?
transport solutes down
a gradient
188
What is active transport?
can transport solutes against the concentration
189
what are two characteristics of transpprt systems?
specific
saturable
190
How are nutrients usually acquired in unicellular organisms?
active transport
191
How are nutrients usually acquired in multicellular organisms?
facilitated diffusion
192
Name 2 types of facilitated diffusion
carrier mediated
channel-mediated
193
What does active transport use to transport the substrate
against the concentration
gradient?
energy
194
What are 3 components of ATP-binding cassette?
membrane-spanning protein
ATP-hydrolyzing protein
substrate-specific protein
195
Where is the ABC transporter in gram negative?
periplasm
196
Where is the ABC transporter in gram positive?
cytoplasmic memebrane
197
What is responsible for the first step of glycolytic pathway?
group translocation
198
what are growth factors?
organic molecules that the microorganism needs for growth but cannot synthesize by
itself.
199
How do most prokaryotes multiply?
Binary fission
200
What is generation time?
time needed for the
population to double
201
What is the lag phase?
time needed by the bacteria to adjust to the new condition
202
What is the exponential phase?
doubling of population at a constant rate
203
what is the stationary phase?
limiting nutrients are depleted or accumulation of a waste
product that inhibits growth; growth is stopped.
204
what does barophilic mean?
grow best at high pressure
205
What helps resist high temperatures?
endospores
206
How does life adapt to low PH?
Changes of the cytoplasmic membrane to resist high concentration of protons.
207
How does life adapt to high pH?
Changes of the cytoplasmic membrane to resist low concentration of protons
. – Use of Na+ gradient for transport and motility (low concentration of protons outside, pmf is hard to
maintain)
.– Keep the electron transport chain close to the ATPase, so protons that are pumped out do not diffuse away.
208
What are halophiles?
Microorganisms that can grow at high salt concentrations
209
What is sterilization?
The killing or removal of all viable organisms ( including endospores)
210
211
What is inhibition?
effectively limiting microbial growth
212
What is decontamination?
the treatment of an object to make it safe to handle
213
What is disinfection?
directly targets the removal of all pathogens, not necessarily all microorganisms
214
what are 3 antimicrobial physical control methods?
heat
radiation
filtration
215
What are 2 chemical antimicrobial control methods?
Used on external surfaces: Sterilants, disinfectants, sanitizers, antiseptics.
– Used internally: antibiotics, antivirals, antifungals.
216
What is decimal reduction time?
Amount of time required to reduce viability tenfold
217
What does heat do to macromolecules?
denatures them
218
what is the thermal death time?
the time needed to kill all cells at a given temperature.
219
What kills microorganisms in the autoclave?
high temperature
220
What is pasteurization?
the process of using precisely controlled heat to reduce the microbial load in heat sensitive liquids
221
what is ionizing radiation?
Electromagnetic radiation that produces ions and other reactive molecules
222
Name two types of filters
membrane filters, depth filters
223
What is a bacteriostatic antimicrobial?
inhibit growth of microorganism
224
What is a bacteriocidal antimicrobial?
kill miicroorganism
225
What is a bacteriolytic antimicrobial?
kil microorganism by inducing lysis
226
What is the minimum inhibitory concentration?
e smallest amount of an agent needed to inhibit growth of a microorganism
227
What is minimal bacteriocidal concentration?
lowest concentration of an agent that kills a test bacterium
228
what do antimicrobial compounds do?
prevent spreading of a pathogen in the environment, prevent contamination of the host and cure superficial bacterial infections.
229
What is a sterilant?
destroy all forms of microorganisms, including endospores. Called COLD
STERILIZATION
230
What is an antiseptic?
applied to the surface of living tissues or skin (must not be toxic for animals/humans). Do not kill endospores
231
How are antimicrobial drugs classified?
molecular structure
mechanism of action
spectrum of antimicrobial activity
232
What are the requirements for a good antimicrobial drug?
no severe side effects
low risk/benefit ratio
broad spectrum of activity
appropriate bioavailability and pharmacokinetics
low cost
233
What did Paul Ehrlich do?
studied selective toxicity
drug to treat syphilis
234
What are quinolones?
antibacterial compounds that interfere with DNA gyrase
235
What are antibiotics?
antimicrobial agents naturally produced by a variety of bacteria and fungi to inhibit or kill other microorganisms.
236
Who discovered penicillin?
Alexander fleming
237
What is penicillin effective against?
positive bacteria, inhibits cell wall synthesis
238
What is antimicrobial drug resistance?
the acquired ability of a microorganism to resist the effects of a chemotherapeutic agent to which it is normally
sensitive.
239
How do bacteria resist antiniotics?
destruction of the antibiotic
protection of target site by modification reduce intracellular concentration with efflux pump
