Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Microbial world > Lecture 5 and 6 > Flashcards

Lecture 5 and 6 Flashcards

1
Q

What is a flagella?

A

A filamentous protein structure attached to the cell surface that provides a swimming movement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How do flagella in prokaryotes differ from eukaryotes?

A

The lack the 9+2 arrangement of microtubules

The way they are powered

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the diameter of a prokaryotic flagella?

A

20 nanometers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How are bacterial flagella powered?

A

By a proton motive force established on the bacterial membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How are eukaryotic flagella powered?

A

ATP hydrolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Why are very few cocci motile?

A

They are adapted to dry environments so lack hydrodynamic design

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the several distinct proteins that make up the flagellar apparatus?

A

Basal body, hook structure, flagella filament

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the structure of the basal body?

A

A system of rings embedded in the cell envelope

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What name is given to the shape of bacterial flagella?

A

Helical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How is a flagella different to fimbria and pili?

A

They are longer and thicker

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What name is given to bacteria with no flagella?

A

Atrichous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What name is given to bacteria with flagella distributed all over the bacterial surface?

A

Peritrichous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What name is given when flagella are distributed at one or both ends of the bacteria?

A

Polar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the two names given to describe the number of polar flagella?

A

Monotrichous- one flagellum

Lophotrichous- multiple flagella

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What name is given to describe the distribution of polar flagella?

A

Amphitrichous- flagella at either end

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the filament of the flagella composed of?

A

Flagellin (globular protein)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How is flagellin arranged?

A

In intertwining chains to form a hollow tube

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the purpose of the hook?

A

It is a connector region between filament and basal body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the hook composed of?

A

Flagella hook protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What does the hook act as?

A

A universal joint

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What does the basal body consist of?

A

A small central rod inserted into a series of rings

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What does the basal body function as?

A

A motor, also anchors flagella to cell wall and plasma membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What do gram negative bacteria have in their basal bodies?

A

2 pairs of rings, the outer anchored to cell wall and inner to plasma membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What do gram positive bacteria have in the basal bodies?

A

Inner pair of rings anchored to plasma membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

In what direction do flagella rotate?

A

Both clockwise and anticlockwise

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is interesting about the speed a flagella can be rotated?

A

It can be altered (200-17,000 rpm)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What name is given to movement in one direction of a bacteria?

A

A run, or swim

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What name is given to the change in direction that interrupts runs?

A

Tumbles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is it called when cells move towards favorable or away from adverse environment?

A

Taxis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Name two type of taxis.

A

Chemotaxis

Phototaxis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What names are given to positive and negative taxis stimulus?

A

Attractant and repellant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

When does the frequency of tumbles increase?

A

When bacteria are moving away from repellent stimulus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is an axial filament?

A

A modified flagellum (endoflagella) that is enclosed in space between outersheath and cell wall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Name two examples of spirochete bacteria with axial filaments.

A

Treponema pallidum- syphilis

Borrelia burgdoferi- lyme disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Where is one end of the axial filament attached?

A

Near to polar of cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What does rotation of the axial filament cause?

A

Corkscrew-type movement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What is the plasma membrane?

A

A barrier that separates the cytoplasm from the environment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

How thick is the plasma membrane?

A

6-8nm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Where are photosynthesis complexes found on the plasma membrane of bacteria?

A

Folds called thylakoids or chromatophores

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Name some structures found within the bacterial cytoplasm.

A

Cytoskeleton, nucleoid, ribosomes, inclusion bodies, endospores

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Define nucleoid.

A

Region containing bacterial chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Describe the bacterial chromosome.

A

Generally a singular, circular chromosomes composed of double stranded DNA, not associated with histones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

What does the shape of the bacterial nucleoid depend on?

A

Where the cell is within the cell cycle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Why is the chromosome attached to the cell membrane?

A

Cell membrane proteins responsible for DNA replication and segregation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

When a cell is actively dividing, how many ribosomes may they have?

A

10,000+ ribosomes per cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

What structures give the cytoplasm a granular appearance?

A

Ribosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

What do ribosomes consist of?

A

Two subunits made of proteins and rRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

Why is the difference between the 70s ribosome and 80s ribosomes significant?

A

Difference can be exploited in terms of drug development to block protein production in bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

Give examples of the bacterial ribosome being targeted by antibiotics.

A

Steptomycin and gentamicin bind to 30s subunit

Erthromycin and chloramphenicol bind to 50s subunit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

What is the function of inclusion bodies?

A

Energy reserves or resevoirs of structural building blocks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

What are inclusion bodies?

A

Aggregates of specific material (s) that are not membrane bound

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

What name is given to the reserve of high energy, inorganic phosphate?

A

Metachromatic granules (volutin)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

Give an example of a bacteria that has volutin inclusion bodies.

A

Corynebacterium diphtheriae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

What name is given to the reserve of carbon (not lipid)?

A

Polysaccharide granules (starch/glycogen)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

What name is given to the lipid reserve of carbon?

A

Polyhydroxybutyrate (PHB)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

Give an example of a bacteria that has polysaccharide granule reserves.

A

E. coli

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

Give an example of types of bacteria that have polyhydroxybutyrate reserves.

A

Mycobacterium, Bacillus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

Name another type of molecule that can be stored in inclusion bodies.

A

Sulphur granules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

Name two types of bacteria that store sulphur granules.

A

Purple and green sulfur bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

What structures do bacteria have that compartmentalize bacterial processes?

A

Microcompartments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

What are microcompartments?

A

Non-membrane, organelle like protein shell structures surrounding enzymes, proteins and gas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

Give an example of microcompartments filled with enzymes.

A

Carboxysomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

What is the shape of carboxysomes?

A

Polyhendral shape

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

In what type of bacteria are carboxysomes commonly found?

A

Many autotrophic bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

What is the long name for rubisco?

A

Ribulose 1,5-diphosphate carboxylase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

What do carboxysomes contain?

A

Rubisco

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

What shape are gas vacuoles?

A

Hollow cylinders

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

In what type of bacteria are gas vacuoles commonly found?

A

Aquatic bacteria such as cyanobacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

Why is adjusting buoyancy important?

A

To be able to move up and down the bacteria column to be able to photosynthesize.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

What type of intracellular structure might be found in magnetic responsive bacteria?

A

Magnetosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

What type of magnetic substance is commonly found in magnetosomes?

A

Iron oxide (magnetite)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

What is the purpose of magnetosomes?

A

Can be used to orientate and migrate bacteria along geomagnetic lines field lines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

What is the structure of a magnetosome?

A

Membranous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

What is the barrier between the lumen of the microcompartment and the cytosol formed of?

A

Conserved families of proteins assembled into a selectively permeable shell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
75
Q

How many structural groups of shell proteins are there that make up microcompartment shells?

A

3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
76
Q

Give an example of bacterial microcompartments being adapted for bioengineering in plants.

A

Enhancing CO2 fixation by installing carboxysomes in chloroplasts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
77
Q

What are some other potential applications for engineered microcompartments?

A

Serving as nano-factories for biochemical production, or as novel drug delivery devices

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
78
Q

What type substance stored in a microcompartment may be toxic to certain insects?

A

Parasporal crystals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
79
Q

Name a bacteria that has magnetosomes.

A

Magnetospirillum spp and several gram negative bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
80
Q

Name a bacteria that produces parasporal crystals.

A

Endospore-forming Bacillus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
81
Q

How can parasporal crystals be potential exploited?

A

As insecticides.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
82
Q

What is an endospore?

A

A dormant, tough, non-reproductive structure produced by some bacteria to ensure survival through periods of environmental stress

83
Q

In what bacteria are endospores found?

A

Some gram positive bacteria (Bacillus, Clostridium)

84
Q

How are endospores dispersed?

A

Wind, water, animal gut

85
Q

What is the name given to endospore formation?

A

Sporulation

86
Q

What is the name given to the return to vegetative state from endospore?

A

Germination

87
Q

When does sporulation occur?

A

When key nutrients become scarce/unavailable (environmental stress)

88
Q

How long does it take for sporulation to occur?

A

Several hours

89
Q

What is the first step in sporulation?

A

Newly replicated chromosome and some cytoplasm become isolated by ingrowth of plasma membrane (spore septum)

90
Q

What happens after the replicated chromosome has become isolated?

A

The mother cell engulfs the spore, double layed membrane surrounds the chromosome and cytoplasm, creating a forespore

91
Q

What happens to the newly formed forespore?

A

A thick layer of peptidoglycan is laid down between the 2 membranes

92
Q

What happens after the peptidoglycan is laid down between the two membranes?

A

Spore coat (made of protein) is laid down around the outermembrane, forming endospore. Cytoplasm of endospore becomes dessicated.

93
Q

What is important about the shape and position of an endospore?

A

It varies in different species, so is useful for classification and identification purposes.

94
Q

Name the three types of position of an endospore.

A

Terminal spores, subterminal spores, central spores.

95
Q

What are the three distinct phases of endospore germination?

A

Activation, germination, outgrowth

rapid, takes few minutes

96
Q

How can activation of endospores occur?

A

Heating activated spores conditioned to germinate

97
Q

What occurs during germination?

A

In the presence of nutrients (amino acids- alanine) spore becomes metabolically active

98
Q

What occurs during outgrowth of endospores?

A

Uptake of water, RNA, DNA protein synthesis begins, vegetative cell emerges

99
Q

What 4 structures are found in all bacteria?

A

Cytoplasm, ribosomes, plasma membrane, nucleoid

100
Q

What is a cell wall?

A

A complex, semi-rigid structure that maintains cell shape

101
Q

How is the cell wall related to osmosis?

A

Prevents osmotic lysis of cell

102
Q

What is another function of the cell wall?

A

To serve as an attachment point for appendages such as flagella, pili, fimbri etc.

103
Q

What is a major component of bacterial cell walls?

A

Peptidoglycan

104
Q

What are the two alternating sugars that peptidoglycan consists of?

A

N-acetyglucosamine (NAG or G)

N-acetylmuramic acid (NAM or M)

105
Q

How are NAG and NAM connected?

A

By a Beta-1,4 glycosidic bond

106
Q

What are 2 amino acids that peptidoglycan is made of?

A

Lysine, diaminopimelic acid (DAP)

107
Q

What is attached to N-acetylmuramic acid?

A

A peptide chain of three to five amino acids, which can be cross-linked to the other peptide chain of another strand

108
Q

What is unusual about the amino acids found in the cell wall of bacteria?

A

They can alternate between L- and D- forms (only L-form amino acid are used in proteins)

109
Q

What enxyme can break the B1-4 linkages?

A

Autolysins (found in lysozome)

110
Q

What aspect of cross linking varies between species?

A

The degree of cross linking

111
Q

How does cross linking effect the cell wall?

A

Provides strength, more cross linking = greater rigidity

112
Q

What name is given to the peptide chains linking directly between each glycan backbone?

A

Transpeptidation

113
Q

What name is given to a bridge that can connect peptide chains indirectly?

A

Pentapeptide bridge

114
Q

What effect does pentapeptide bridges have on the cell wall?

A

Makes the cell wall more flexible

115
Q

What is the structure of a pentapeptide bridge?

A

5 gly amino acids

116
Q

Give an example of a bacteria that has a pentapeptide bridge in its cell wall.

A

Staphylococcus aureus (gram positive)

117
Q

Give an example of a bacteria that has transpeptidation.

A

Escherichia coli (gram negative)

118
Q

What antibiotics stops the formation of cross links in bacterial cell walls?

A

Beta-lactam antibiotics, such as penicillin and cephalosporins

119
Q

How do beta-lactam antibiotics stop cross link formation?

A

They inhibit transpeptidase

120
Q

What does transpeptidase do?

A

Catalyses the formation of the final bond between two peptide chains (transpeptidation)

121
Q

How thick is the peptidoglycan layer in gram negative bacteria?

A

2-5nm

122
Q

How thick is the peptidoglycan layer in gram positive bacteria?

A

Up to 25nm

123
Q

How much of the cell wall is made up of peptidoglycan in gram positive bacteria?

A

90%

124
Q

What else can be found in the petidoglycan layer of many gram positive bacteria?

A

Teichoic acids (glycopolmers)

125
Q

What are the two parts of a teichoic acid?

A

Disaccharide linkage unit

Main chain polymer

126
Q

What is the structure of the disaccharide linkage unit in teichoic acids?

A

N-acetylmannosamine beta(1,4) bonded to N-acetylglucosamine-1-phosphate

127
Q

How conserved is the disaccharide linkage until across bacteria species?

A

Highly conserved

128
Q

What is the structure of the main chain polymer in teichoic acids?

A

Glycerophosphate or ribitol phosphate polymer which binds to sugars and D-alanine

129
Q

What properties do main chain polymers of teichoic acids have?

A

Zwitterionic properties (+ and - electrical charge)

130
Q

How conserved are main chain polymers in teichoic acids across bacterial species?

A

Not conserved

131
Q

What are the two types of teichoic acid?

A 
Lipoteichoic acid (LTA) 
Wall teichoic acid (WTA)
132
Q

What is a lipoteichoic acid?

A

The disaccharide linkage unit attaches to diacylglycerol in the cell membrane

133
Q

What does lipoteichoic acid interact with?

A

The main chain polymer interacts with petidoglycan

134
Q

What does the linkage unit of wall teichoic acid bind with?

A

N-acetylmuramic acid in the petidoglycan chain

135
Q

What happens to a cell without teichoic acid?

A

It dies

136
Q

What is the function of teichoic acid?

A

Still unknown, could attract cations/anions (gives rigidity to cell wall or regulate their movement), could regulate blastosomes

137
Q

What does the main chain of a WTA interact with?

A

Peptidoglycan and into the surrounding environment

138
Q

What is pathogenesis?

A

The manner of development of a disease

139
Q

How are teichoic acids involved in pathogenesis?

A

They promote adherence to host tissues

140
Q

Give an example of teichoic acids promoting adherence to host tissues.

A

Mediate attachment of staphylocicci to mucosal cells

141
Q

How can teichoic acid induce spetic shock?

A

They can promote injury/damage to organ, causing low blood pressure

142
Q

What is another importance of teichoic acid in medicine?

A

Suspected ligands for toll-like receptors

143
Q

Where are toll-like receptors found?

A

On cells (e.g. macrophages/dendritic cells) of the immune system

144
Q

What can teichoic acid do to toll-like receptors?

A

Trigger innate immune response and development of antigen-specific acquired immunity

145
Q

As a general rule, are gram negative or gram positive bacteria better at getting into our bodies?

A

Gram negative

146
Q

What percentage does peptidoglycan make up of the outermembrane of gram negative bacteria?

A

10%

147
Q

Where is the peptidoglycan layer found in gram negative bacteria?

A

In the periplasm- between outer and plasma membrane

148
Q

How wide is the periplasm?

A

15nm

149
Q

What is the periplasm?

A

Gel-like fluid containing degradative enzymes, binding proteins, chemoreceptos, detoxifying enzymes

150
Q

Name three degradative enzymes found in the periplasm.

A

Phosphatatses (degrade phosphate containing compounds)
Proteases (degrade proteins/peptides)
Endonucleases (degrade nucliec acid)

151
Q

Name a detoxifying enzyme found in the periplasm.

A

Beta-lactamase- degrades Beta-lactam antibiotics

152
Q

What does the outermembrane of gram negative bacteria contain?

A

Lipopolysaccharides, lipoproteins, phospholipids

153
Q

What is the role of the outermembrane in gram negative bacteria?

A

Aids in evading phagocytosis, acts as a barrier to antibiotics, enzymes, detergents, heavy metals, bile salts, dyes, and prevents molecules in periplasm being lost

154
Q

What name is given to transporter proteins in the outermembrane of gram negative bacteria?

A

Porins (can be specific and non-specific)

155
Q

What is embedded in the top layer of the outermembrane of gram -ve bacteria?

A

Lipopolysaccharides

156
Q

What do lipopolysaccharides do?

A

Stabilise outer membrne, increase negative charge, protect from chemical attack

157
Q

What three main parts do lipopolysaccharides consist of?

A

Lipid A
Core polysacchairde
O-polysaccharide

158
Q

What does lipid A consist of?

A

Phosphorylated glucosamine disaccharide and fatty acids

159
Q

What do the fatty acids in lipid A do?

A

Anchor LPS into the outermembrane

160
Q

What else does lipid A function as?

A

An endotoxin- released when gram negative bacteria die and are degraded

161
Q

What do endotoxins do?

A

Elicit symptoms associated with infection- fever, blood vessel dilation, vomit, diarrhoea, blood clotting

162
Q

What does the core polysaccharide of LPS contain?

A

Sugars

163
Q

What is the role of the core polysaccharide in LPS?

A

Structural role, provides stability, role varies between species.

164
Q

What else is the O-polysaccharide known as?

A

O-antigen or O-chain

165
Q

What is the O-polysaccharide made of?

A

Repetitive sugar polymer

166
Q

What are the two types of O-chains found in bacteria?

A

Long O-chains (Smooth LPS)

Shorter O-chains (rough LPS)

167
Q

What do O-chains do?

A

Prevent hydrophobic molecules from getting to outer membrane surface
Extend into the external environment
Function as antigens

168
Q

What are some bacteria with rough LPS more susceptible to?

A

Hydrophobic drugs

169
Q

Do O-chains vary?

A

Greatly between bacterial species and strains (e.g. 160 in E.coli)

170
Q

How are O-chains useful in medicine?

A

Distinguishing between strains of the same species

171
Q

Name a strain of E.coli.

A

E coli O157:H7

172
Q

What does E coli O157:H7 cause?

A

Enteroheamorrhagic fever

173
Q

What does H7 mean?

A

The strain of flagelar antigen

174
Q

When was the gram stain test developed and by who?

A

1884

Christian Gram

175
Q

What is the first step of the gram stain test?

A

Heat fixed cells treated with primary stain, crystal violet

176
Q

What is the second step of the gram stain test?

A

The stain is washed off and the smear treated with a mordant (iodine)

177
Q

What does mordant mean?

A

A substance that combines with a dye or stain and fixes it in a material

178
Q

What happens to cells after the are treated with iodine?

A

The cells are washed with a decolourising agent (alcohol)

179
Q

What happens to the cells after they are treated with alcohol?

A

The smear is counterstained with safranin and observed under the microscope

180
Q

Name two mycobacterium.

A

Mycobacterium tuberculosis

Mycobacterium leprae

181
Q

Describe the cell wall of mycobacterium.

A

Cell wall contains thin layer of peptidoglycan, surrounded by mycolic acid

182
Q

What is mycolic acid?

A

Hydrophobic, waxy lipid (hence can’t be stained, and also repels antibiotics)

183
Q

How can mycobacterium instead be stained?

A

With carbolfuchsin which binds to components of the cytosol after the cells are heated to make mycolic acid more pliable

184
Q

Name some wall-less bacteria.

A

Mollicutes (mycoplasma)

185
Q

How are mycoplasma bacteria protected?

A

Their plasma membrane contains sterols which give rigidity and protect the cell from lysis

186
Q

What is a glycocalyx?

A

A viscous, gelatinous polymer surrounding the cell secreted by most bacteria

187
Q

What is the glycocalyx composed of?

A

Polysaccharides and/or protein, composition varies within a species

188
Q

What are the two types of glycocalyx?

A

Capsule, slime layer

189
Q

How do capsules and slime layers vary?

A

Capsule is well organised and firmly attached to cell wall, slime layer is unorganised and loosely attached to cell wall

190
Q

How are glycocalyx and biofilms associated?

A

The glycocalyx assists in the attachment to surfaces

191
Q

What bacteria can adhere to teeth?

A

Steptococcus mutans

192
Q

What bacteria can adhere to the small intestine?

A

Vibrio cholera

193
Q

What bacteria can adhere to and colonise the respiratory tract?

A

Klebsiella

194
Q

The glycocalyx can also help in the evasion of…

A

the immune system (phagocytosis)

195
Q

The glycocalyx helps resist ______ (the loss of water)

A

desiccation

196
Q

How can the glycocalyx aid nutrient supply?

A

It can be degraded and the sugars used as an energy source.

Viscosity can prevent loss of nutrients

197
Q

What is one more function of the glycocalyx?

A

Facilitate cell to cell communication by acting as a medium for chemical signalling

198
Q

What are fimbriae?

A

Short, stiff, hair-like proteinaceous appendages found predominantly in gram negative bacteria

199
Q

Where are fimbriae found and how many are there?

A

At poles or along entire surface (rods have them at poles)

Few to several hundred

200
Q

What do fimbriae do?

A

Stick cells to each other and to surfaces, such as during biofilm formation (colonization can occur)

201
Q

Give an example of fimbriae adhering to surfaces.

A

In E.coli O157:H7, when fimbriated, it adheres to lining of small intestine

202
Q

What are pili?

A

Hair-like, proteinacrous appendage, longer than fimbriae, only 1 or 2 per cell

203
Q

What are 3 functions of pili?

A

Adherence to surfaces, motility, sex (conjugative pili)

204
Q

How do type IV pili enable motility?

A

Synthesis of pili until it reaches surface, retraction as it is dismantled.
Twitching motility- short, jerky, intermittent motion
Gliding motility

Microbial world (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions