Ch 2: Microbial Cell Structure & Function Flashcards
(166 cards)
1
Q
3 usual cell shapes in microbes
A
- coccus
- rod
- spirillum
2
Q
3 unusual cell shapes in microbes
A
- spirochete
- budding and appendaged bacteria
- filamentous bacteria
3
Q
what are characteristic arrangements in cells
A
cells remain in groups and clusters even after cell division in characteristic arrangement that can assist in identification
4
Q
different ways of cell arrangement examples
A
- cocci in chains
- cocci in clusters
- rods in chains
5
Q
what is morphology
A
genetically encoded property that maximizes fitness in a particular habitat
6
Q
how can morphology maximize fitness
A
- optimization of nutrient uptake
- swimming motility in viscous environments of near surfaces
- gliding motility (like filamentous bacteria
7
Q
Can the morphology predict physiology, ecology or phylogeny of a cell
A
typically, no
8
Q
what is the size range for prokaryotes
A
~0.2um – 700 um in diameter
9
Q
size of the average rod in bacteria
A
2 um
10
Q
what is the size of most eukaryotes
A
8 um or larger
11
Q
examples of very large prokaryotes
A
- Epulopiscium fishelsoni (bigger than 600 um)
- thiomargarita namibeinsis (400-750 um)
12
Q
how does thiomargarita magnifica survive
A
by oxidixing sulfur. They are thread like creatures that are 50 times bigger than any other known bacteria
13
Q
Small cells have more _______ relative to cell volume than large cell
A
surface area
14
Q
core difference between small and large cell
A
the high surface are to volume ratio
15
Q
what are the benefits of a large surface area
A
- support greater nutrient exchange
- grow faster than large cells
16
Q
Limited resources can work out for small cells or large cells
A
small. a large population of small cells can be taken care of, compared to large population of large cells
17
Q
What are the benefits of having more cell division, which is easier in small cells
A
more cell divisions = more mutations = faster evolution
18
Q
In cells that really small, what should the volume of a cell consist of
A
proteins, nucleic acids, ribosomes etc - so it may get difficult
19
Q
what cell size are needed on a minimum
A
0.15 um is marginal. 0.1 is insufficient
20
Q
usually cell size in open oceans
A
0.2 - 0.4 um in diameter
21
Q
what is the size of pathogenic bacteria
A
very small.
22
Q
If pathogenic bacteria are small, how do they accommodate all cell functions
A
their genomes are streamlined with some gene functions provided by hosts
23
Q
what is the cytoplasmic membrane
A
a thin structure that surrounds the cytoplasm and separates it from the environment
24
Q
what does the cytoplasmic membrane do
A
regulates traffic of substances into and out of the cell
25
what happens if the cytoplasmic membrane disrupts
cell dies
26
what holds all of the contents of the cell in one place
cytoplasmic membrane
27
what is selectively permeability
regulation of traffic of substances that go in and out of the cell
28
what is constitutes of the cytoplasmic membrane
composed of hydrophobic (fatty acid) and hydrophilic (glycerol phosphate) components
29
is fatty acid hydrophobic or hydrophilic
hydrophobic
30
is glycerol-phosphate hydrophilic or hydrophobic
hydrophilic
31
In what environment to phospholipids naturally form a bilayer
aqueous solution
32
how are the fatty acids organized in the bilayer
fatty acids point inwards and the hydrophilic portions remain exposed to the external of cytoplasm
33
what is the cytoplasmic membrane
semi-fluid phospholipid bilayer with embedded proteins
34
what are integral membrane proteins
they're permanently embedded in the membrane.
35
what proteins span the membrane
transmembrane integral proteins
36
chemical structure of the lipid-anchored proteins
lipid molecule attached to an amino acid -- which inserts into the membrane
37
What is the peripheral membrane
on the surface of the membrane, without inserting
38
in archaea how are hydrocarbons derived?
from isoprene
39
what is isoprene
5 carbon branched molecule
40
in archaea how are hydrocarbons attached to glycerol
by ether linkages
41
In bacteria eukarya, with links the hydrocarbon with glycerol
ester linkages
42
in bacteria archaea, how are hydrocarbons derived
fatty acids
43
3 membrane proteins
1. integral membrane proteins
2. lipid-anchored proteins
3. peripheral
44
What are the 2 major types of archaeal lipids
1. Glycerol diethers
2. diglycerol tetraeither
45
Chemical structure of glycerol diethers
2 phytanyl groups attached to a glycerol
46
What is a phytanyl
20 carbon branched hydrocarbons, basically 4 isoprene units
47
what is a isoprene
5 carbon chain with double bonds
48
chemical structure of diglycerol tetraether
2 biphytanyl groups attached to a glycerol molecule at both ends
49
what is a biphytanyl molecule
20 carbon branched hydrocarbons
50
What does a diglycerol tetraether form instead of a lipid bilayer
lipid monolayer
51
what is the benefit of cyclic rings in hydrocarbon chains
increased rigidity
52
example of a archaea that has cyclic rings in its lipids
crenarchaeol
53
types of archaeal membranes
1. lipid bilayer
2. lipid monolayer
3. combination of bilayer and monolayer
54
which type of archaeal lipid membrane is extremely resistant to heat
lipid monolayers
55
which type of archaeal lipid monolayer are widely there in hyperthermophilic archaea
lipid monolayer
56
what is hyperthemophilic
organisms that can live in extreme hot environments. they can grow best at more than 80 C
57
in permeable membranes what portion of the membrane is a tight barrier for difussion of substances
hydrophobic portion
58
can water pass through the phospholipid molecules
No its too small to pass
59
Why cant water pass through phospholipid membrane
water is a polar molecule (charged) and the head of the phospholipid molecule is non polar molecule (uncharged) . A polar molecule cannot diffuse/dissolve through a non polar molecule. Anything that can diffuse through the bilayer has to be similar to a non polar
60
How is water transported into the cell
through membrane proteins called aquaporins
61
What are the 3 transport mechanisms in prokaryotes (to and fro the phospholipid bilayer)
1. simple transport
2. group translocation
3. abc transporter
62
what is simple transport in prokaryotes
passive diffusion of substances - without using energy - typically driven by the proton motive force (?)
63
what is group translocation in prokaryotes
when a subtance is diffused through the bilayer wile being chemically modified
64
What is ABC transporter in prokaryotes
they are membrane bound proteins that pump substances in and out of cells
65
What does ABC transportation need
1. substrate protein
2. membrane transporter
3. ATP Hydrolyzing protein
66
What is the proton motive force
When there is an abundance of H+ (protons) on one side [of the cell] compared to the other side, there is force that is created, and they want to come to the other side where is a net negative charge - thats proton motive force
67
what is an ATP hydrolyzing protein
Hydrolyzing means breakdown. The hydrolyses of ATP powers cellular activities. The proteins that hydrolyze ATP are called ATP hydrolyzing proteins (like ATP Synthase)
68
2 main purposes of the cell wall
1. protects against lysis (breaking of or disintegration)
2. gives shape and rigidity to the cell
69
What is difference between gram-positive and gram-negative bacteria
differ in staining due to cell wall structure difference
70
What are gram-positive bacteria
thick cell wall. have thick layer of peptidoglycan (envelope around the cytoplasmic membrane aka the phospholipid bilayer) + inner cytoplasmic membrane
71
what are gram negative bacteria
thin cell wall. Thin layer of peptidoglycan + inner cytoplasmic membrane + outer membrane
72
when staining, what color are gram positive bacteria. what is the name of the stain
purple. A basic fuchsin stain is used.
73
when staining, what color are gram negative bacteria. what is the name of the stain
pink. basic fuchsin stain
74
do gram postive bacteria has an outer membrane
no
75
what is the chemical structure of peptidoglycan
repeating subunits of glycan tetrapeptide
76
What is there in a glycan tetrapeptide
1. 2 Sugar derivatives
2. amino acids
77
What are the 2 sugar derivatives in glycan tetrapeptide
1. N-acetlyglucosamine
2. N-acetlymuramic acid
78
what amino acids are there in glycan tetrapeptide
1. L-Alanine
2. D-Alanine
3. D-Glutamic Acid
4. L-lysine OR a lysine derivative (like, Diaminopimelic acid)
79
what enzyme can weaken the cell wall
lysozyme
80
Examples of where lysozyme is present
1. Tears
2. saliva
3. other bodily fluids
81
what do B-1,4-glycosidic bonds connect
sugars in a long chain
82
what do peptide bonds connect
one glycan chain to another
83
What is main feature of glycosidic bonds
create rigidity and strength in one direction (X)
84
What is the main feature of peptide bonds
give strength in other direction (Y)
85
How do glycosidic and peptide bonds work together
work together in peptidoglycan. Imagine an axis, peptide bonds work in Y direction and glycosidic bonds work in X direction
86
in gram negative bacteria, where do peptide bonds occur
between DAP of one chain and D-Alanine of another chain
87
In gram positive bacteria, how are connections formed
through a short string of peptides, an interbridge, whose form varies from species to species
88
what is a glycine residue
unique amino acid chain where all side chains are hydrogen atoms
89
gram positive cell walls contain up to _____ % of peptidoglycan
90
90
what are the "cables" in gram positive cell walls
"cables" are basically cross linked glycan strands, about 50 nm wide and the these cables itself can cross link to form an even stronger structure
91
What are teichoic acids
polymers in gram positive bacteria. They help to regulate cell morphology and cell divisions
92
are teichoic acids found in gram positive or negative acids
only in gram positive bacteria
93
what is the chemical structure of techoic acids
polymers of glycerol or ribitol joined by phosphate groups
94
to what are techoic acids connected in gram positive bacteria
to the peptidoglycan or plasma membrane lipids
95
are teichoic acids positively or negatively charged
negatively. bacterial cell walls are also negatively charged. and teichoic acids is in the bacterial cell wall
96
In gram - negative bacteria what is the outer membrane
it is a lipid bilayer
97
in gram negative bacteria, what is the composition of the inner membrane
thin peptidoglycan layer
98
what does the outer membrane in gram negative bacteria contain
1. phospholipids
2. lipopolysaccharides or LPS
99
How abundant is LPS (lipopolysaccharide) in the outer membrane
it covers most of the phospholipids in the outer half of the outer membrane
100
what connects the peptidoglycan layer (inner membrane) to the outer membrane
lipoproteins `
101
What does the structure of LPS consist of
1. Lipid A
2. Core Polysaccharide
3. O-Specific polysaccharide
102
what is the chemical structure of lipid A in LPS
Disaccharide of glucosamine phosphate linked to fatty acids through amine groups
103
what is the periplasm
region between two membranes
104
What happens in the periplasm
very high conc of proteins:
1. hydrolytic enzymes, these degrade food molecules
2. binding protiens, used for transport
3. chemoreceptors, which aid cell movement
105
what is porins
Proteins that function as channels for entrance and exit of solutes
106
why is the outer membrane relatively permeable to small molecules
due to the presence of porins
107
Which bacteria (negative / positive) cells are nearly invisible until stained with 2nd dye
gram negative
108
What happens to the CV-Iodine complex in gram positive and negative cells during the staining process
gram-negative cells: alcohol goes into the cells and extract CV-Iodine, leaving it colorless
gram-positive cells: alcohol dehydrates, causing pores to close and trapping the CV-Iodine complex, leaving it purple
109
can most prokaryotes live without a cell wall
no
110
Examples of prokaryotes that naturally lack cell walls
1. Thermoplasma and its relatives
2. Mycoplasma
111
How do prokaryotes without cell wall survive
1. have tough cell membranes
2. Or live in strict osmotic regulated environment
112
What does it mean to have a osmotic regulated environment
it is a homeostatic mechanism that regulates the optimum temperature of water and salts in the tissues and body fluids
113
Do archaea cell walls contain peptidoglycan `
no
114
do archaea contain an outer membrane
no
115
What kind of cell walls do archaea have
pseudomurein cell walls
116
What are pseudomurein cell walls
- similar to peptidoglycan
- contains N-acetylglucosamine linked to N-acetylalosaminuronic acid
117
some archaea that live in _______ environment have polysaccharide walls
high salt
118
The cell walls of archaea that live in high salt environments have a high amount of ----
They're highly sulfated. SO4^2-
119
what is the most common type of cell wall in archaea
S-Layer
120
Are S-layer cell walls found in bacteria
in some bacteria, yes
121
How is the S-Layer formed
interlocking layers of:
- Protein/Glycoprotien
That form a paracrystalline structure
122
What does S-Layer do
1. protects from osmotic lysis
2. Acts as a selective sieve
3. retains proteins near surface
123
What is the S - Layer present with (sometimes?
Polysaccaride-based layer
124
what are cell inclusions
granules, crystals or globules of a substance in the cytoplasm, usually partitioned off from the rest of the cell
125
What can cell inclusions be used for
used as store substances when in excess for later use
126
What are some examples of substances that can be stored in cell inclusions
1. Carbon
2. Inorganic Phosphate
3. Sulfur
127
where are gas vesicles present?
in many planktonic prokaryotes
128
What are gas vesicles made of
protein
129
What are gas vesicles shaped like
Spindle-shaped
130
What are gas vesicles permeable to
gases
131
what are gas vesicles impermeable to
water
132
Advantages of gas vesicles
1. Increases buoyancy
2. Allow cells to adjust vertical position in a water column
133
what are slime layers
sticky or slimy materials on cell surface that have secreted polysaccaride or protein
134
what is the structure of bacterial capsules?
consist of tight matrix that adheres firmly to the cell wall
135
how are slime layers attached to the cell surface
loosely attached, so they can be lost from the cell surface
136
what is the function of capsules and slime layers
1. Help in attachment
2. protect immune invasion
3. protect from dehydration
137
difference between fimbriae and pilli
Fimbriae are bristle-like short fibers occurring on the bacterial surface, Pili are long hair-like tubular microfibers found on the surface of bacteria.
138
What are fimbriae and pilli
filamentous proteins extending from surface of cell
139
What is the function of fimbriae
helps enable cells to stick to surfaces
140
What are the functions of pilli
1. facilitate genetic exchange by conjugation
2. adhesion to specific host tissues
3. twitching motility
141
what is flagella
Threadlike locomotor appendages extending outward from the plasma membrane and cell wall
142
What is the function of flagella
Swimming and motility
143
what are the 4 different forms of flagella arrangements
1. Polar
2. Lophotrichous
3. Amphitrichous
4. Peritrichous
144
What is the polar arangement of flagella
Flagella attached at one or both ends
145
What is the lophotrichous arrangement of flagella
A tuft (group) of flagella at one end
146
What is the amphitrichous arrangement of flagella
Tufts at both ends
147
what is the peritrichous arrangement of flagella
Many locations around the cell
148
What are the 3 main components of flagella
1. Basal Body
2. Hook
3. Filament
149
What is the basal body in flagella
The base & “motor” of the flagella
150
what is the function of the basal body in flagella
Anchors the flagella in cytoplasmic membrane & cell wall
151
What is the hook in flagella
links basal body and filament
152
What is the filament in flagella
Extends from the cell surface to the tip
153
What is the structure of the filament in flagella
- Composed of a hollow rigid cylinder of flagellin protein
- Helical
154
How does the basal body move the flagella
rotates the flagella much like the propeller on a boat motor
155
what powers the rotation done by the basal body in flagella
protons, through Mot proteins
156
How is the flagella in archaea used
power swimming motility
157
Compared to bacterial flagella, what is the size of the archaea flagella
its thinner in diameter
158
How does a thin diameter affect swimming on archaea
slower swimming
159
what are archaea flagella made of
different flagellin proteins, similar to bacteria flagellin
160
what powers the swimming done by flagellla in archaea
ATP. and not proton motive force
161
Did flagellar motility evolve together for bacteria and archaea
no, they evolved separately
162
Flagella rotational speed is related to ______
strength of the proton motive force
163
Why do different archaea species have different swimming maximum speeds
because swimming speed is genetic, hence different for each species
164
How does different flagella arrangements, affect swimming
the swimming motions differ with flagella arrangement
165
What type of flagellated cells move slowly in a straight line
peritrichously flagellated cells
166
What type of flagellated cells move more rapidly, spinning around and dashing from place to place
polarly flagellated cells
