Bacterial Cell Structure I & II (Lecture 4, 5, and 6) Flashcards
(122 cards)
1
Q
Flagella
A
long, helical protein filaments attached to a complex integral membrane protein “machine”
2
Q
Protein filament in flagella is made from…
A
a protein monomer called flagellin
3
Q
Can cells have more than one flagella?
A
YES
4
Q
How do flagella move a cell?
A
it rotates to propel a cell (could be counterclockwise/clockwise)
5
Q
What drives flagella rotation?
A
proton passage
6
Q
Do all bacteria have flagella?
A
no
7
Q
Monotrichuous
A
single polar flagellum
8
Q
Amphitricuous
A
a flagellum at each pole
9
Q
Lophotricuous
A
multiple flagella localized at the cell pole
10
Q
Peritricuous
A
multiple flagella inserted at many locations in the cell membrane
11
Q
Counterclockwise rotation
A
pushes cell forward
12
Q
How does Peritricuous flagella arrange during CCW rotation?
A
they bundle together
13
Q
Some Monotrichuous cannot ________________.
A
rotate CCW
14
Q
Clockwise rotation for Peritricuous
A
they tumble or change direction
15
Q
What can bidirectional Monotrichuous do?
A
back track
16
Q
What direction do unicdirectional monotrichuous move?
A
forward
17
Q
Bacterial movement via flagella and twitching motility is _______________.
A
directed
18
Q
Taxis
A
directed movement in response to chemical or physical gradients
19
Q
Chemotaxis
A
response to chemicals the best studied movement system
20
Q
Phototaxis
A
response to light
21
Q
Aerotaxis
A
response to oxygen
22
Q
Osmotaxis
A
response to ionic strength
23
Q
Hydro taxis
A
response to water
24
Q
Random movement is caused by…
A
no attractant present
25
Directed movement is directed by...
presence of attractant
26
How do we measure chemotaxis?
by inserting a capillary tube containing an attractant or a repellant in a medium of motile bacteria
27
Endospore
a dormant non-reproductive structure that allows bacterial survival in harsh environmental conditions
28
1 spore equals
one cell
29
What are endospores highly resistant to?
temperature, chemical disinfectants, desiccation, ration, and lysozyme
30
Do all bacteria form endospores?
no it is limited to gram-positive bacteria in the bacillus and clostridium genuses
31
What is sporulation generally triggered by?
nutrient starvation particularly for carbon and nitrogen
32
Bacteria persists as spores and germinates under ______________________________________
conditions that allow it to replicate
33
DNA is ________ to fit the _________.
packed to fit the cell
34
What DNA is in the bacterial nucleiod?
a closed loop of double-stranded DNA
35
How is DNA condensed?
by supercoiling
36
What is the nucleoid attached to?
cell envelope
37
Chromosome must replicate _____________ for each cell division.
at least once
38
The oldest bacteria spore ever to be revived in a lab was...
250 million years old
39
Surface coat of vegetative cells
40
Surface coat of endospores
41
Microscopic appearance of vegetative cells
42
Microscopic appearance of endospores
43
Enzymatic activity of vegetative cells
44
Enzymatic activity of endospores
45
Macromolecule synthesis of vegetative cells
46
Macromolecule synthesis of endospores
47
Heat resistance of vegetative cells
48
Heat resistance of endospores
49
Resistance to chemicals and acids of vegetative cells
50
Resistance to chemicals and acids of endospores
51
Radiation resistance of vegetative cells
52
Radiation resistance of endospores
53
Sensitivity to lysozymes of vegetative cells
54
Sensitivity to lysozymes of endospores
55
Sensitivity to dyes of vegetative cells
56
Sensitivity to dyes of endospores
57
What does the outer surface of the cytoplasmic membrane do?
- interact with a variety of substrates
-process large molecules for transport
58
What does the inner surface of the cytoplasmic membrane do?
-interact with substrates involved in energy-yielding reactions and other important cellular function
59
Integral membrane protein
firmly embedded in the membrane
60
Peripheral membrane proteins
one portion anchored in the membrane
61
three major classes of transport systems in prokaryotes
1. simple transport
2. group translocation
3. abc transporter
62
Simple transport
driven by the energy in the proton motive force H+
63
Group translocation
chemical modification of the transported substance driven by phosphoenolpyruvate
64
ABC transporter
periplasmic binding proteins are involved and energy comes from ATP
65
What do simple transport, group translocation, and abc transporter all require?
energy in some form usually proton motive force or ATP
66
Is nutrient transport specific?
yes highly
67
Uniport
transport in one direction across the membrane
68
Symporters
function as co-transporters
69
Antiporters
transport a molecule across the membrane while simultaneously transporting another molecule in the OPPOSITE direction
70
Which is faster carrier transport or simple diffusion?
carrier transport
71
For carrier transport, if it has a high enough concentration of solute the rate of entry/exit will reach a ________________.
maximum the transporter is saturated
72
Capsules and slime layers have ____________ layers.
polysaccharide
73
How might the capsule/slime layers be described?
they may be thin or thick and rigid or flexible
74
Are capsules closely associated with eukaryotes?
no, bacteria
75
Are slime layers associated with bacteria?
loosely and easily removed
76
Both capsules and slime layers function to...
1. assist in attachment to surfaces
2. protect against phagocytosis
3. resist desiccation
77
Do all bacteria have capsules/slime layers?
no
78
Fimbriae structure
short, helical, filamentous protein structures
79
How many Fimbriae per cell?
1000
80
What is the function of Fimbriae?
enables organisms to stick to surfaces or each other
81
Do all bacteria have Fimbriae?
no
82
Pili
thin filamentous protein structures
83
Which is longer Fimbriae or pili?
pili
84
What are the functions of pili?
1. allow for bacterial attachment to surfaces
2. sometimes allow movement via twitching motility
3. helps bacteria to evade components of the innate immune system
85
Conjugal pilus function
allows for exchange of DNA from one bacteria to another
86
Twitching motility mechanism
1. pili extends
2. pili binds receptor
3. pili retracts pulling bacteria along
87
Repeating twitching motions allows what?
allows the bacteria to move along surfaces
88
What pili can perform the twitch mechanism?
TYPE IV ONLY
89
What two species utilize twitching motility?
neisseria and pseudomonas
90
Conjuntion
plasmid or piece of the chromosome can be transferred via a specialized sex/conjugal pilus
91
Conjunction mechanism
sex pili grab another cell, they are stuck together and exchange genetic info
92
Structures in a general bacterial cell structure
1. flagella
2. plasmid
3. inclusion
4. nucleoid
5. cell membrane
6. plasmid
7. ribosome
8. cell wall
9. cytoplasm
10. pili
11. glycocalyx
93
What is the bacterial cell wall composed of?
peptidoglycan
94
What is peptidoglycan?
1. polysaccharides (sugar/glycan) chains wrapped in circles around cell
2. sugar chains crosslinks by polymers of glycine bounded to L-Lysine and D-alanine
95
What happens if we block the cross linking of peptidoglycan?
the bacteria dies
96
What did Gram observed?
bacteria that retained crystal violet die after treatment with ethanol while others did not and required counter staining
97
Gram positive characteristics
-stains purple
-a thick cell wall
-lipoteichoic acids
(capsule, periplasm, s-layer, plasma membrane)
98
What do lipoteichoic acids do?
strength the cell wall
99
Gram negative characteristics
-stains pink
-doesn't retain crystal violet
-thin cell wall
-outer and inner membranes
100
Do all species have capsules?
no
101
Do all species have s-layers?
no
102
What is an s-layer?
layer made of protein
103
What is the thick cell wall of gram + cells composed of?
9 amino acid cross-links in peptidoglycan with lipoteichoic acids
104
Periplasm Gram +
space found between the inner membrane and peptidoglycan layer
105
Periplasm Gram -
found between the inner and outer membranes
106
The outer membrane of gram - bacteria is made of _________-.
LPS; lipopolysaccharides
107
Thin cell wall of gram - bacteria has...
4 amino acid crosslinks in peptidoglycan
108
Cytoplasmic membrane
surround cell and separates cytoplasm from the environment
109
What is the cytoplasmic membrane composed of?
a phospholipid bilayer studded with membrane proteins
110
What does the phospholipid bilayer do?
allows certain things to come through while keeping others out (Semipermeable membrane)
111
Hopanoids
pentacyclic chemicals that act to stabilize the bacterial membrane (similar to cholesterol in eukaryotes)
112
Membrane functions
1. permeability barrier
2. protein anchor
3. energy conservation
113
permeability barrier
mediates nutrient and waste transport prevents leakage allows for production of chemical gradients
114
protein anchor
holds transport proteins, enzymes, and other structures in place
115
energy conservation
generation of proton motive force
116
composition of membranes
generally a phospholipid bilayer
117
phospholipids are composed of:
hydrophilic head (water loving) and hydrophobic tails (water hating)
118
hydrophilic heads orient to...
the aqueous environment
119
hydrophobic tails interact with...
each other
120
Complex lipid construction aka the head and tail
contains C, H, O, P, N, or S
121
Complex lipid construction membranes are primarily made of...
phospholipids
122
Glycerol is linked to...
1. two fatty acids
2. a phosphate group
