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Microbiology and Parasitology - Lecture > Microbial Cell Structure and Function > Flashcards

Microbial Cell Structure and Function Flashcards

1
Q

uses visible light to illuminate cells

A

Compound light microscope

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2
Q

Many different types of light microscopy:

A

Bright-field
Phase-contrast
Dark-field
Fluorescence

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3
Q

the ability to make an object larger

A

Magnification

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4
Q

Maximum magnification is

A

~2,000✕

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5
Q

the ability to distinguish two adjacent objects as separate and distinct

A

Resolution

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6
Q

is determined by the wavelength of light used and numerical aperture of lens

A

Resolution

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7
Q

Limit of resolution for light microscope is about

A

0.2 μm

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8
Q

Specimens are visualized because of differences in
contrast (density) between specimen and surroundings

A

Bright-field scope

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9
Q

improves contrast

A

Staining

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10
Q

are organic compounds that bind to specific cellular materials

A

Dyes

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11
Q

Examples of common stains are

A

methylene blue, safranin, and crystal violet

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12
Q

separate bacteria into groups

A

Differential stains

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13
Q

Bacteria can be divided into two major groups:

A

gram-positive and gram-negative

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14
Q

appear purple

A

Gram-positive bacteria

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15
Q

appear red after staining

A

gram-negative bacteria

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16
Q

Phase-contrast microscopy was invented in ______________ by ________________________

A

1936 by Frits Zernike

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17
Q

Improves the contrast of a sample without the use of a stain

A

Phase-contrast microscopy

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18
Q

Phase ring amplifies differences in the refractive index of cell and surroundings

A

Phase-contrast microscopy

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19
Q

Allows for the visualization of live samples

A

Phase-contrast microscopy

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20
Q

Light reaches the specimen from the sides

A

Dark-field microscopy

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21
Q

Light reaching the lens has been scattered by specimen

A

Dark-field microscopy

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22
Q

Image appears light on a dark background

A

Dark-field microscopy

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23
Q

Excellent for observing motility

A

Dark-field microscopy

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24
Q

Used to visualize specimens that fluoresce

A

Fluorescence microscopy

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25
Q

Specific on staining DNA

A

DAPI

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26
Q

use electrons instead of photons to image cells and structures

A

Electron microscopes

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27
Q

Two types of electron microscopes:

A

Transmission electron microscopes (TEM)
Scanning electron microscopes (SEM)

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28
Q
  • Electromagnets function as lenses
  • System operates in a vacuum
  • High magnification and resolution (0.2 nm)
  • Enables visualization of structures at the molecular level
  • Specimen must be very thin (20–60 nm) and be stained
    (osmic acid,permanganate, uranium lanthium or lead
    salts)
A

Transmission electron microscopy (TEM)

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29
Q
  • Specimen is coated with a thin film of heavy metal (e.g., gold)
  • An electron beam scans the object
  • Scattered electrons are collected by a detector, and an
    image is produced
  • Even very large specimens can be observed
  • Magnification range of 15✕–100,000✕
A

Scanning electron microscopy (SEM)

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30
Q

cell shape

A

Morphology

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31
Q

Major cell morphologies

A
  • Coccus (pl. cocci)
  • Rod
  • Spirillum
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32
Q

spherical or ovoid

A

Coccus (pl. cocci)

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33
Q

cylindrical shape

A

Rod

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34
Q

spiral shape

A

Spirillum

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35
Q

Cells with unusual shapes

A

Spirochetes, appendaged bacteria, and filamentous bacteria

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36
Q

Size range for prokaryotes

A

0.2 µm to >700 µm in diameter

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37
Q

Examples of very large prokaryotes

A
  • Epulopiscium fishelsoni
  • Thiomargarita namibiensis
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38
Q

Size range for eukaryotic cells:

A

10 to >200 µm in diameter

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39
Q

Thin structure that surrounds the cell

A

Cytoplasmic membrane

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40
Q

Vital barrier that separates cytoplasm from environment

A

Cytoplasmic membrane

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41
Q

Highly selective permeable barrier; enables concentration of specific metabolites and excretion of waste products

A

Cytoplasmic membrane

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42
Q

Firmly embedded in the membrane

A

Integral membrane proteins

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43
Q

One portion anchored in the membrane

A

Peripheral membrane proteins

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44
Q

Ether linkages in phospholipids of Archaea

A

Archaeal membranes

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45
Q

Major lipids are

A

glycerol diethers and tetraethers

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46
Q

Holds transport proteins in place

A

Protein anchor

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47
Q

Generation of proton motive force

A

Energy conservation

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48
Q

What are used for magnification?

A

Objective lens and ocular lens

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49
Q

Total magnification =

A

objective magnification ✕ ocular magnification

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50
Q

Differential stains:

A

the Gram stain

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51
Q

Resulting image is dark cells on a light background

A

Phase-contrast microscopy

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52
Q

Dark-field microscopy is excellent for observing __________________

A

motility

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53
Q

Emit light of one color when illuminated with another color
of light

A

fluoresce

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54
Q

Cells fluoresce naturally..example

A

Chlorophyll

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55
Q

Widely used in microbial ecology for enumerating
bacteria in natural samples

A

Fluorescence microscopy

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56
Q

Can stain both live (less efficient) and fixed cells

A

DAPI

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57
Q

Excited by an ultraviolet light (358nm) emit blue
color (461nm).

A

DAPI

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58
Q

Enables visualization of structures at the molecular level

A

Transmission electron microscopy (TEM)

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59
Q

Surface area:

A

increased 4x

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60
Q

Volume:

A

increased 8x

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61
Q

Composition of membranes
* General structure is ___________________________

A

phospholipid bilayer

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62
Q

how wide is cytoplasmic membrane

A

8–10 nm wide

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63
Q

Cytoplasmic membrane is stabilized by

A

hydrogen bonds and hydrophobic interactions

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64
Q

help stabilize membrane by forming ionic
bonds with negative charges on the phospholipids

A

Mg2+ and Ca2+

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65
Q

Ether linkages in phospholipids of Archaea

A

Archaeal membranes

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66
Q

Bacteria and Eukarya that have ester linkages in
phospholipids

A

Archaeal membranes

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67
Q

Archaeal lipids lack ________________; have ________________ instead

A

fatty acids; isoprenes

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68
Q

contains 4 5 carbon cyclopentyl and 1 6 carbon cylohexyl

A

Crenarcheol

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69
Q

Functions of the cytoplasmic membrane

A
  • Permeability barrier
  • Protein anchor
  • Energy conservation
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70
Q
  • Show saturation effect – capacity of the carrier proteins
  • Highly specific – accommodate specific or closely (ex.
    Amino acid) related molecules
  • Highly regulated
A

Carrier-mediated transport systems

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71
Q

Three major classes of transport systems in prokaryotes

A
  • Simple transport
  • Group translocation
  • ABC system
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72
Q

Driven by the energy in the proton motive force

A

Simple transport

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73
Q

Chemical modification of the transported substance driven by phosphoenolpyruvate

A

Group translocation

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74
Q

Periplasmic binding proteins are involved and energy comes from ATP

A

ABC transporter

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75
Q

Three transport events are possible:

A

uniport, symport, and antiport

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76
Q

transport in one direction across the membrane

A

uniport

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77
Q

function as co-transporters

A

symport

78
Q

transport a molecule across the membrane while simultaneously transporting another molecule in the opposite direction

A

antiport

79
Q

Gram-negative cell wall
Two layers:

A

LPS and peptidoglycan

80
Q

Gram-positive cell wall
One layer:

A

peptidoglycan

81
Q

Rigid layer that provides strength to cell wall

A

Peptidoglycan

82
Q

Gram-positive cell walls can contain up to ___________ peptidoglycan

A

90%

83
Q

Gram-positive cell walls are common to have ______________________ (acidic substances) embedded in their cell wall

A

teichoic acids

84
Q

teichoic acids covalently bound to membrane lipids

A

Lipoteichoic acids

85
Q

Prokaryotes that lack cell walls

A
  • Mycoplasmas
  • Thermoplasma
86
Q

Group of pathogenic bacteria

A

Mycoplasmas

87
Q

Species of Archaea

A

Thermoplasma

88
Q

have sterols on their cell membrane

A

Mycoplasma

89
Q

have lipoglycans in their cell membrane

A

Thermoplasma

90
Q

Most of cell wall composed of ________________________, aka
_______________________

A

outer membrane; lipopolysaccharide

91
Q

LPS consists of

A

core polysaccharide and O-polysaccharide

92
Q

the toxic component of LPS

A

Endotoxin

93
Q

space located between cytoplasmic and outer
membranes

A

Periplasm

94
Q

Houses many proteins including those filtered by the outer
membrane

A

Periplasm

95
Q

channels for movement of hydrophilic low-molecular-weight substances

A

Porins

96
Q

Facilitates the entry of materials needed by the cell that by the outer membrane

A

Porins

97
Q

water filled channels where small substances can pass through

A

Non-specific Porins

98
Q

contain binding site for specific or structurally related
substances

A

Specific Porins

99
Q
  • No peptidoglycan
  • Typically no outer membrane
A

Archaeal Cell Walls

100
Q

Polysaccharide similar to peptidoglycan

A

Pseudomurein

101
Q

Cell walls of some Archaea lack

A

pseudomurein

102
Q

Found in cell walls of certain methanogenic Archaea

A

Pseudomurein

103
Q
  • Most common cell wall type among Archaea
  • Consist of interlocking protein or glycoprotein
A

S-Layers

104
Q

Allows the archea to withstand strong osmotic pressure

A

S-Layers

105
Q

Serves as a filter to only allow solutes of lower molecular
weight

A

S-Layers

106
Q

Resistant to lysozyme

A

S-Layers

107
Q

thin sheets of cells on a liquid surface

A

pellicles

108
Q

Enable organisms to stick to surfaces or form pellicles
(thin sheets of cells on a liquid surface) or biofilm

A

Fimbriae

109
Q

Also enhances bacterial virulence as it assist disease
process (attachment to tissue)

A

Fimbriae

110
Q

Typically longer than fimbriae

A

Pili

111
Q

Facilitate genetic exchange between cells (conjugation)

A

Pili

112
Q

genetic exchange between cells

A

conjugation

113
Q

involved in twitching motility

A

Type IV pili

114
Q

Receptor for certain viruses

A

Pili

115
Q

lipid compose of 3-18 carbons

A

Poly-β-hydroxybutyric acid (PHB)

116
Q

glucose polymer

A

Glycogen

117
Q

accumulations of inorganic phosphate

A

Polyphosphates

118
Q

composed of elemental sulfur stored in the periplasm

A

Sulfur globules

119
Q

Carbonate minerals: composed of

A

barium, strontium, and magnesium

120
Q

magnetic storage inclusions (iron oxide mineral magnetite Fe3O4 )

A

Magnetosomes

121
Q

Allows the bacterial cells to orient themselves within a
magnetic field. Not observed in archea

A

Magnetosomes

122
Q

Confer buoyancy in planktonic cells

A

Gas vesicles

123
Q

Spindle-shaped, gas-filled structures made of protein

A

Gas vesicles

124
Q

Gas vesicles are composed of two proteins

A

GvpA and GvpC

125
Q

water tight vesicle shell

A

GvpA

126
Q

strengthen the shell of the gas vesicle

A

GvpC

127
Q

Highly differentiated cells resistant to heat, harsh
chemicals, and radiation

A

Endospores

128
Q
  • Ideal for dispersal via wind, water, or animal gut
  • Present only in some gram-positive bacteria
A

Endospores

129
Q

Endospore structure
- Core contains

A

small acid-soluble spore proteins (SASP)

130
Q

structure that assists in swimming

A

Flagella

131
Q

Different arrangements of Flagella:

A
  • peritrichous (everywhere)
  • polar (on side)
  • lophotrichous (many flagella on one side)
132
Q

everywhere

A

peritrichous

133
Q

on side

A

polar

134
Q

many flagella on one side

A

lophotrichous

135
Q

flagella shape is

A

helical

136
Q

Flagellar structure of Bacteria
- filament composed of different types of protein called

A

flagellin

137
Q

Flagellar structure of Bacteria
- Move by

A

rotation- like a propeller

138
Q

Flagellar structure of Archaea
- Move by

A

rotation

139
Q

increase or decrease rotational speed in
relation to strength of the proton motive force

A

Flagella

140
Q

move slowly in a straight line

A

Peritrichously flagellated cells

141
Q

move more rapidly and typically spin around

A

Polarly flagellated cells

142
Q
  • Flagella-independent motility
  • Slower and smoother than swimming
A

Gliding motility

143
Q
  • Movement typically occurs along long axis of cell
  • Requires surface contact
A

Gliding motility

144
Q

Mechanisms of gliding motility

A
  • Excretion of polysaccharide slime
  • Type IV pili
  • Gliding-specific proteins
145
Q

directed movement in response to chemical or physical gradients

A

Taxis

146
Q

response to chemicals

A

Chemotaxis

147
Q

response to light

A

Phototaxis

148
Q

response to oxygen

A

Aerotaxis

149
Q

response to ionic strength

A

Osmotaxis

150
Q

response to water

A

Hydrotaxis

151
Q

Chemotaxis is best studied on

A

E.coli

152
Q

“Run and tumble” behavior

A

Chemotaxis

153
Q

Chemotaxis
Attractants and receptors sensed by

A

chemoreceptors

154
Q

contain a membrane-enclosed nucleus and other
organelles

A

Eukaryotes

155
Q

contains the chromosomes

A

Nucleus

156
Q

DNA is wound around

A

histones

157
Q

Visible under light microscope without staining

A

Nucleus

158
Q

Within the nucleus is the

A

nucleolus

159
Q

Site of ribosomal RNA synthesis

A

nucleolus

160
Q
  • Normal form of nuclear division in eukaryotic cells
  • Chromosomes are replicated and partitioned into two
    nuclei
A

Mitosis

161
Q

Mitosis results in

A

two diploid daughter cells

162
Q
  • Specialized form of nuclear division
  • Halves the diploid number to the haploid number
A

Meiosis

163
Q

Meiosis results in

A

four haploid gametes

164
Q

All specialize in energy metabolism

A

Mitochondria, Hydrogenosomes, and Chloroplast

165
Q
  • Respiration and oxidative phosphorylation
  • Bacterial dimensions (rod or spherical)
  • Over 1,000 per animal cell
  • Surrounded by two membranes
A

Mitochondria

166
Q

Mitochondria has folded internal membranes called

A

cristae

167
Q

Contain enzymes needed for respiration and ATP
production

A

cristae

168
Q

Innermost area of mitochondrion called

A

matrix

169
Q

Contains enzymes for the oxidation of organic compounds

A

matrix

170
Q
  • Similar size to mitochondria; however, lack TCA cycle
    enzymes and cristae
  • Oxidation of pyruvate to H2 , CO2 , and acetate
  • Trichomonas and various protists have hydrogenosomes
A

Hydrogenosome

171
Q

Chlorophyll-containing organelle found in phototrophic
eukaryotes

A

Chloroplast

172
Q

Flattened membrane discs are

A

thylakoids

173
Q

Lumen of the chloroplast is called the

A

stroma

174
Q

Stroma contains large amounts of

A

RubisCO

175
Q

RubisCO is key enzyme in

A

Calvin cycle

176
Q

Two types of ER

A

smooth and rough ER

177
Q

participates in the synthesis of lipids

A

Smooth ER

178
Q

is a major producer of glycoprotein

A

Rough ER

179
Q

stacks of membrane distinct from, but functioning in concert with, the ER

A

Golgi complex

180
Q

Modifies products of the ER destined for secretion

A

Golgi complex

181
Q
  • Membrane-enclosed compartments
  • Contain digestive enzymes used for hydrolysis
A

Lysosomes

182
Q

Allow for lytic activity to occur within the cell without
damaging other cellular components

A

Lysosomes

183
Q

25 nm in diameter; composed of α- and β-tubulin

A

Microtubules

184
Q

Function in maintaining cell shape, in motility, in chromosome movement, and in movement of organelles

A

Microtubules

185
Q

7 nm in diameter; polymers of actin

A

Microfilaments

186
Q

Function in maintaining cell shape, motility by pseudopodia,
and cell division

A

Microfilaments

187
Q

8–12 nm in diameter; keratin proteins

A

Intermediate filaments

188
Q

Function in maintaining cell shape and positioning of
organelles in cell

A

Intermediate filaments

189
Q

Organelles of motility allowing cells to move by swimming

A

Flagella and cilia

190
Q

are short flagella

A

Cilia

191
Q

is attached to the microtubules and uses ATP

A

Dynein

192
Q

Flagella and cilia propel the cell using a

A

whiplike motion

Microbiology and Parasitology - Lecture (6 decks)

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