Textbook Flashcards (theme 1 & 3 Page 1-16)
(199 cards)
1
Q
What biological kingdom do microorganisms belong to
A
Protista
2
Q
What do microorganisms include
A
Eukaryotes
Prokaryotes
Viruses
Viroids
Prions
3
Q
How are microorganisms classified
A
Structure
Chemical composition
Biosynthetic organisation
Genetic organisation
4
Q
Round bacteria is called
A
Coccus
5
Q
Rod like bacteria is called
A
Bacillus
6
Q
Why is the third bacteria shape
A
Spiral
7
Q
Cocci and bacilli grow in doublets, this is called
A
Diplococci
8
Q
Cocci and bacteria that grow in chains are called
A
Streptococci
9
Q
Cocci that grow in clusters are called
A
Staphylococci
10
Q
What is an example of bacterial species that are pleomorphic
A
Bacteroides
11
Q
What are pleomorphic bacteria
A
Bacteria of different shapes
12
Q
What antibiotic can affect cell wall biosynthesis and alter the shape of the bacteria
A
Penicillin
13
Q
What is the nucleus of bacteria called
A
Nucleoid
Nuclear body
14
Q
Describe bacterial nucleoid
A
Not in nuclear membrane
No mitotic apparatus
15
Q
What is the composition of the nucleoid
A
Polyamine and magnesium ions bounds to negatively charged,circular,supercoiled, double stranded DNA, small amounts of RNA, RNA polymerase and other proteins
16
Q
What does the cytoplasm of bacteria contain
A
Ribosomes
Nutritional storage granules
No organelles
17
Q
Explain what Bacterial ribosomes consist of
A
70s sedimentation coefficient
30s and 50s subunits
16s, 23s, 5s RNA in subunits
18
Q
Bacterial ribosome structure
A
If engaged in protein biosynthesis they are membrane bound
19
Q
Describe how antibiotics affect bacterial ribosomes
A
Protein biosynthesis is inhibited
Some selectively target 70s
20
Q
What does erythromycin do
A
An antibiotic that targets 70s ribosome
21
Q
Cytochromes and enzymes of the phospholipid bilayer are part of
A
Electron transport
Oxidative phosphorylation
22
Q
What constituents of the cell membrane of bacteria are involved in cell wall biosynthesis
A
Carrier lipids
Enzymes
Penicillin binding proteins (PBP)
23
Q
What other parts of the phospholipid bilayer are there
A
Chemoreceptors
Enzymes involved in phospholipid synthesis and DNA replication
24
Q
Where is the site of action of some antibiotics such as polymyxin
A
Cell membrane
25
What is the function of the bacterial cell membrane
Selectively permeable
Active transport through membrane bound permeases, binding proteins and transport systems
26
What are mesosomes
Inward foldings of plasma membrane
27
What is the function of a septal mesosome
Connect plasma membrane to nucleoid
Assist in septum formation and replication during cell division
28
Function of lateral mesosome
Made of respiratory enzymes
Similar to eukaryotic mitochondrion
29
What are plasmids
Nonchromosomal double stranded DNA circles
30
What can plasmids do
Self replicate
Can integrate with bacterial DNA
31
Function of plasmids
Genes for antibiotic resistance
Virulence factors
Transmissibility to other bacteria
32
Virulence is the ability of an organism to infect a host and cause disease, give examples of virulence factors
Toxins
Surface coats inhibiting phagocytosis
Surface receptors that bind to hosts
33
What is conjunction
Plasmid transfer from direct physical contact of cells
34
What are plasmids called when they are used experimentally to clone, transfer and manipulate genes
Vectors
35
What are transposons
small parts of DNA that move between bacterial DNA and plasmids
Don’t self replicate
36
What can code for antibiotic resistant enzymes, metabolic enzymes or toxins in bacteria
Transposons
37
A function of transposons is
Altering expression of neighbouring genes or cause mutations for insertion
38
What is the cell envelope made of
Macromolecular layers
39
An outer membrane layer is found in which type of bacteria
Gram negative
40
What genus of bacteria and other members of of the class mollicutes lack a cell wall and peptidoglycan layer around their cell membrane
Mycoplasma
41
What is glycocalyx
Surface layer that covers cell membrane of many bacteria , epithelial and other cells
42
Cell envelope of bacteria can contain
Capsule and glycocalyx layer or both
43
What part of the cell envelope induce an antibody response
Antigens
44
What does the cell wall refer to
External to cytoplasmic membrane
Internal to capsule or glycocalyx
45
What does the cell wall allow us to deduce
Gram staining characteristics
Osmotic protection
46
What is gram positive bacteria composed of
Thick Peptidoglycan layer
Teichoic and teichuronic acids
Polysaccharides
47
Gram negative bacteria is composed of
Thin peptidoglycan layer
Lipoprotein
Outer phospholipid membrane containing lipopolysaccharide
48
Lists functions of bacterial capsule
Inhibits phagocytic uptake in non immune people
Immunogenic
49
Function of Surface proteins in gram positive bacteria
Virulence factors:
Adhesions
Immunogens
Inhibitors of phagocytosis
50
Where can teichoic acids only be found
Gram positive bacteria
51
The cell wall of gram positive bacteria is made of
Peptidoglycan
52
Describe the structure of peptidoglycan
Net like
Gives shape to cell wall
Protection from osmotic shock
May have some teichoic acids anchored
53
Describe Penicillin binding proteins structure and function
They are transpeptidases and carboxytransferases that cross link peptidoglycan components
Involved in biosynthesis of peptidoglycan
54
Why are lipoteichoic acids attached to
Cytoplasmic membrane
55
What is the order of the cell envelope of some gram positive bacteria from apical to basal
Capsule
Surface proteins
Cell wall
Cytoplasmic membrane
56
What is the order of the cell envelope of some gram negative bacteria from apical to basal
Capsule
Outer membrane
Periplasmic space
Inner membrane
57
What does the outer membrane of gram negative bacteria do
Makes periplasmic space
Has: outer membrane proteins (OMPs) like porins that stop aqueous flow in and out, adhesions and immunogens
58
Peptidoglycan layer in gram negative bacteria does what
Traps or slows components decreased out of inner membrane in periplasmic space
59
What are beta lactamases
Enzymes that inactivate beta lactam antibiotics by hydrolysing peptide bond of 4 membered beta lactam ring, causing resistance
60
What is an endotoxin and where can it be found
A lipopolysaccharide
Structural component of gram negative outer membrane
61
What is lipid a an it’s function
Toxin
When released by dying gram negative cell triggers gram negative symptoms shock
62
What is the O antigen that is attached to lipid A which is toxic and part of the outer membrane of gram negative bacteria
A polysaccharide that’s immunogenic
63
Peptidoglycan is found in all bacteria cell walls except
Mycoplasma
64
Other names for peptidoglycan are
Mucopeptide
Murein
65
What is the structure of peptidoglycan, the backbone and linkages
Backbone: Alternating NAG and NAM units
Linkages: identical tetrapeptide side chains
66
How do the side chains of peptidoglycan link to other layers
Side chains are attached to NAM, link to adjacent tetrapeptides by identical peptide cross bridges or direct peptide bonds
67
What bond is cleaved by bacteriolystic enzyme lysosome
Beta-1,4 glycosidic bond between NAM and NAG
68
What amino acid may peptidoglycan have in it’s structure that is unique to prokaryotic cell walls
Diaminopimelic acid
69
Peptidoglycan is the site of action for certain antibiotics such as
Penicillin
Cephalosporins
70
Which bacteria have a larger peptidoglycan layer
Gram positive bacteria
71
Teichoic acid and teichuronic acid are water soluble polymers that contain
Ribitol or glycerol residue linked by phosphodieter bonds
72
Gram positive bacteria cell walls or cell membranes are the only place that contain
Teichoic acid and teichuronic acid
73
teichoic acid are found in gram positive cell walls, what are they chemically bound to
Peptidoglycan
74
Lipoteichoic acid is found in cell membranes of only gram positive bacteria, what is it chemically bound to ?
Membrane glycolipids
(Especially in mesosomes)
75
What is the function of teichoic and teichuronic acid
Bacterial surface antigenic determinants
76
What is the function of lipoteichoic acid
Anchors cell wall to cell membrane
77
Lipoproteins are only found in
Gram negative bacteria
78
Which type of bacteria has lipoproteins
Gram negative
79
What cross links the peptidoglycan layer and outer membrane of gram negative bacteria
Lipoproteins
80
How is the lipoproteins linked to diaminopimelic acid residues of peptidoglycan tetrapeptide side chains
Peptide bonds
The lipid portion in noncovalently inserted into outer membrane
81
What is the periplasmic space of gram negative bacteria
Area between inner and outer membrane
82
What is found in the periplasmic space
Hydrated peptidoglycan layer
Hydrolytic enzyme: beta lactamases,
Carrier molecules, oligosaccharides
83
What is different about the hydrophobic outer membrane of gram negative bacteria
Phospholipid of the outer layer are replaced by lipopolysaccharides
84
outer membrane contains
Embedded proteins such as matrix porins (nonspecific pores)
85
What other proteins are found in the outer membrane
Non pore proteins: phospholipases and proteases
Transport proteins
86
What is the function of the outer membrane
Protects cell from harmful enzymes and antibiotics
Prevents leakage of periplasmic proteins
87
Lipopolysaccharide has lipid A, what is it’s structure
Long chain fatty acids attached to phosphorylated glucosamine disaccharide units, a polysaccharide composed of a core and terminal repeating units
88
What is the charge of lipid A and how is it linked
Negative charge
Noncovalently cross-bridged by divalent cations
89
Lipid A is also known as an
Endotoxin
90
Lipid A is also known as an
Endotoxin
91
What is the function of lipid A
Contains major surface antigenic determinants, including O antigen found in polysaccharide part
92
What are protein secretion systems
Important in bacteria interacting with their environment, determine pathogenicity especially for gram-negative
93
What are protein secretion systems
Important in bacteria interacting with their environment, determine pathogenicity especially from gram-negative
94
How many classes of systems do gram negative bacteria have
6 classes of systems
95
What classes do gram positive bacteria have
A few of the 6 classes that gram negative have and an additional unique class
96
Give an example of a Bacteria that has more than one type of secretion system in a class
Salmonella typhimurium has 2 types of T3SS
97
Give an example of a simple proteins secretion system
T1SS
Transporters
outer membranes factors
Membrane fusion proteins
98
T3SS is a more complex protein secretion system because
Involves a transmembrane structure, an injectisome that’s consists of more than 25 proteins
99
Why is an injectisome
A specialised protein export system used by many gram negative bacteria that deliver virulence proteins into hosts they infect
100
What is the function of protein secretion systems
To transport proteins or nucleic acids to outside of cell, periplasm or into host cells
101
Which protein secretion system transports nucleic acids
T4SS
102
What do transported proteins of the protein secretion system do
Become surface proteins like adhesions or toxins and effector proteins that modify host cell physiology
103
Where are surface proteins found
External to cell wall of some gram positive bacteria
104
Why is the function of surface proteins
Antiphagocytic
Adhesions that facilitate tissue colonisation with several species like staphylococcus aureus (fibronectin binding proteins) and streptococcus pyogenes (f protein)
105
Describe the capsule
Polysaccharide structure surrounding cell
External to cell wall
106
What bacteria does not have a polysaccharide capsule
Bacillus anthracis
107
What is the capsule of bacillus anthracis made of
Poly-D-glutamic acid
108
What is the function of a capsule
Protection from phagocytosis
Part of bacterial adherence
109
What is the glycocalyx
Loose network of polysaccharide fibrils surrounding some bacterial cell walls
110
What synthesis glycocalyx
Surface enzymes
111
What is the function of glycocalyx
Adhesive properties
Contains antigenic sites
112
What are flagella
Protein appendages for locomotion
Contain antigenic determinants
113
What is the structure of flagella
Basal body
Hook
flagellin- long filament of polymerised protein
114
What are polar and peritrichous flagella
Polar- one area
peritrichous- entire surface
115
What are polos
Rigid surface appendages mainly made of pilin protein
116
Common pili are involved in
Adhesion
Gram positive cell conjunction
117
Sex pili are involved in
Attachment of donor and recipient bacteria in gram negative cell conjunction
118
What is the function of ordinary pili
virulence factor (colonisation antigens)
Associated with neisseria gonorrhoeae
119
What may pili confer
Antiphagocytic properties like M protein of S. pyogenes
120
What are the general characteristics of endospores
Survival response to some adverse nutritional conditions
121
What are endospores
Highly retractile and thick walled structures formed in bacterial cells
122
What two bacterial species commonly form endospores
Bacillus
Clostridium
123
Bacterial endospores are metabolically inactive simplified forms of the bacteria, what do they consist of
DNA genome
Small amount of cytoplasm
Specialised coating
124
What are endospores highly resistant to
Desiccation (moisture removal)
Heat
Various chemicals
125
What does the endospores core contain
Spore wall
Cortex
Coat
Exosporium
126
What does the endospore core contain that aids in heat resistance
Calcium dipicolinate
127
What does the endospore core contain that aids in heat resistance
Calcium dipicolinate
128
Endospore function
Germinate under favourable nutritional conditions after activation involving damage to spore coat
129
What are biofilms
Aggregates of bacterial cells that form in soil, marine environments and medical implant devices
130
What can biofilms do
Enhance nutrient uptake
Exclude antimicrobials
131
How do bacteria reproduce
Binary fission
132
How can bacterial growth be measured
Cell concentration
Biomass density
133
How can bacterial growth be measured
Cell concentration
Biomass density
134
Cell concentrations are measurements of viable cells using which methods
Serial dilutions and then colony forming units are determined with an agar surface
135
What measurements are used for cell concentration that include both viable and nonviable cells
Turbidimetric density
(Spectrophotometer allow light to pass through, higher the turbidity the higher the concentration)
136
What is the bacterial growth curve
Inoculation of bacteria from saturated culture into fresh liquid media
137
How are bacterial growth curves illustrated
Plot of logarithmic number of bacteria against time
138
How are bacterial growth curves illustrated
Plot of logarithmic number of bacteria against time
139
What is generation time
Time needed for cells to double during log phase of growth
140
What are the 4 phases of the bacterial growth curve I
Lag
Exponential
Stationary
Death
141
What occurs during the lag phase of the growth curve
Metabolite depleted cells adapt to new environment
142
In which phase does the cell biomass get synthesised at a constant rate, cells in this phase are also more susceptible to antibiotics
Exponential phase
143
In the stationary phase of the growth curve what do cells do
Exhaust nutrients or
Accumulate toxic products
144
Synchronous growth refers to
Bacteria in a culture dividing at the same moment.
145
What methods can achieve synchronous growth
Thymidine starvation
Alternate low and optional incubation temp
Spore germination
Selective filtration of young & Old cells
Trapped cell filtration
146
Bacterial cultivation refers to
Propagation of bacteria
147
What preferences is bacterial cultivation based on
Specific pH
Gaseous
Temperature
148
The liquid or agar growth medium used used for bacterial cultivation contains
Carbon source r
Nitrogen source
Energy source
Inorganic salts
Growth factors
Electron donors and acceptors
149
What is superoxide disputes
An enzyme in
aerobes and
facultative and
aerotolerant anaerobes
150
What does superoxide disputes allow aerobes and others to do
To gram in the presences of superoxide free radical (O2-)
151
What reaction does superoxide dismutase carry out
2O2- + 2H+ —> H2O2 + O2
152
What is produced in the reaction carried out by superoxide dismutase that is toxic to cells
Hydrogen peroxide
153
The hydrogen peroxide produce in the superoxide dismutase reaction is destroyed by
Catalyse or
Oxidised by a perioxidase enzyme
154
Obligate aerobe
Require oxygen for growth
Contain superoxide dismutase, protecting them from O2-
155
Obligate aerobe
Require oxygen for growth
Contain superoxide dismutase, protecting them from O2-
156
What is the superoxide free radical
O2-
157
What is killed by the superoxide free radical
Obligate anaerobes
158
When do obligate anaerobes a grow maximally?
At a pO2 concentration of less than 0.5% to 3%
159
What do obligate anaerobes lack
Superoxide dismutase
Catalyse
Cytochrome-C oxidase
160
What type of substance do obligate anaerobes require
Hydrogen accepter during generation of metabolic energy
161
The fermentation pathway with distinctive metabolic products is used by which type of bacteria
Obligate anaerobes
162
Where can obligate anaerobes be found
Gut 1000:1
Mouth 100:1
(Ratio to aerobes)
163
99% of total fecal flora is made of
Obligate anaerobes
164
What usually causes poly microbial infections and is foul smelling
Obligate anaerobes
165
Obligate anaerobes are usually found near mucosal surfaces but can escape into tissue by
GI obstruction or surgery
Diverticulitis
Bronchial obstruction
Turner growth
Ulceration of intestinal tract by chemo
166
Facultative aerobes can grow
In the absence and presence of oxygen
167
Facultative aerobes can grow
In the absence and presence of oxygen
168
In the presence of air, facultative aerobes
Shift from fermentation to respiratory metabolism
169
Most pathogenic bacteria are
Facultative bacteria
170
Most pathogenic bacteria are
Facultative bacteria
171
How are the energy needs of facultative aerobes met
They consume less glucose under respiratory metabolism than fermentation ( Pasteur effect )
172
What is different about aerotolerant bacteria from facultative
Have fermentation metabolism in and out of oxygen
173
What do heterotrophs require for growth
Preformed organic compounds such as sugar and amino acids
174
Autotrophs don't need preformed organic compounds for growth because
They synthesise them from inorganic compounds and carbon dioxide
175
Minimal essential growth medium has only the primary precursor compounds essential for growth so the bacteria must
Synthesise most of the organic compounds for growth
Generation time is slow
176
Which bacteria is grown in complex growth medium
Fastidious bacteria
177
What is unique about differential growth medium
Nutrients and pH indicators allow visual distinction
178
What is used to achieve a selective growth medium
Dyes
Sugars
Antibiotics
High salt concentration
pH concentration
179
Bacterial metabolism is the sum of
Anabolic processes and catabolic processes
180
What metabolism is exhibited by pathogenic bacteria
Heterotrophic
181
What is used in sugar transport of bacterial transport systems
Phosphotransferase systems
182
Blood agar is used as a medium for haemolytic bacteria, what are 2 species that are hemolytic
Staphylococcal
Streptococcal
183
What causes alpha hemalysis
Non lysis damage to RBC, media becomes translucent with green tinge around colonies
184
What is beta hemalysis identified by
Lysis of RBC causes media to be transparent around colonies
185
Give example of enteric gram negative rods
E.coli
Klebsiella
Salmonella
Shigella
Proteus
186
Which mediums are used for enteric gram negative rods
Hektoen-enteric agar
Macconkey agar
187
What does hektoen enteric agar contain that inhibits gram positive bacteria
Bile salts
Thiosulfate
Ferric ammonium citrate
Lactose
Sucrose
Lactose and sucrose fermenters are observed and H2S producers are observed
188
Maconkey agar is used for
Enteric gram negative rods
189
What is different about maconkey agar from hektoen agar
Contains
Crystal violet,
lactose
neutral red pH indicator
190
What do bile salts and crystal violet do
Inhibit gram positive bacteria only
191
What gives colonies a colour that determines its species
Gram negatives that ferment lactose
192
What medium is mycobacteria grown on
Lowenstien-Jensen graft media
193
Now is mycobacteria identified on lowenstein Jensen graft media
Glycerated egg potato media with malachite green dye
Penicillin
Nalidixic acid (inhibits gram positive and some gram negative)
194
Thayer martin and martin Lewis media is used for
Neisseria species
195
Thayer martin and martin Lewis medium is made of
Blood again
Gently lysed RBC
Antibiotics to inhibit most normal respiratory and genital flora
196
Fermentation is a method of obtaining metabolic energy defined as
Substrate phosphorylation
197
Explain the steps of cell wall synthesis
Peptidoglycan subunits synthesised in cytoplasm
Subunits translocated by membrane lipid carrier
Cross linked to existing cell wall by enzymes
198
In cell wall synthesis of gram positive cells, what is involved
Covalent linkage of teichoic acid to NAM residues
199
What 3 components are gram negative cell walls made of that are synthesised on or in the cytoplasmic membrane and assembled outside of the cell
Lipoprotein
Outer membrane
Liposaccharide
