Lec 3 Flashcards
1
Q
- Ultrathin sections of
specimens. - Beam passes through
specimen, then an
electromagnetic lens, to
a screen or film. - Specimens may be
stained with heavy
metal salts.
A
TRANSMISSION ELECTRON
MICROSCOPY (TEM)
2
Q
- An electron gun
produces a beam of
electrons that scans the
surface of a whole
specimen - Secondary electrons
emitted from the
specimen produce the
image
A
SCANNING ELECTRON MICROSCOPY
3
Q
- ________
microscopy uses a
metal probe to scan a
specimen - Resolution 1/100 of an
atom
A
SCANNING TUNNELING MICROSCOPY
4
Q
This microscopy uses a
metal and diamond
probe inserted into the
specimen
* Produces 3-D images
* Metal coat not needed
A
Atomic force
microscopy
5
Q
Most bacteria are ______
* A few are pleomorphic
A
monomorphic
6
Q
VARIOUS ARANGEMENTS
Pairs: _________
* Clusters: _______
* Chains: ____________
A
diplococci, diplobacilli
staphylococci
streptococci, streptobacilli
7
Q
Largest prokaryotic cell
A
Thiomargarita namibiensis
8
Q
FUNCTIONS OF PROKARYOTIC
STRUCTURES
Gives bacteria shape and protection from
lysis in dilute solutions
A
Cell Wall
9
Q
FUNCTIONS OF PROKARYOTIC
STRUCTURES
Selectively permeable barrier, mechanical
boundary of cell, nutrient and waste transport,
location of many metabolic processes
(respiration, photosynthesis), detection of
environmental cues for chemotaxis
A
Plasma
Membrane
10
Q
FUNCTIONS OF PROKARYOTIC
STRUCTURES
Resistance to phagocytosis,
adherence to surfaces
A
Capsules and Slime Layers
10
Q
FUNCTIONS OF PROKARYOTIC
STRUCTURES
Attachment to surfaces,
bacterial mating
A
Fimbriae and Pili
10
Q
FUNCTIONS OF PROKARYOTIC
STRUCTURES
Survival under harsh
environmental conditions
A
Endospore
11
Q
Localization of Genetic Material
(DNA)
A
Nucleoid
12
Q
Contains hydrolytic enzymes and
binding proteins for nutrient
processing and uptake
A
Periplasmic
Space
13
Q
Buoyancy for floating in aquatic
environments
A
Gas Vacuole
14
Q
Storage of carbon, phosphate and other
substances
A
Inclusion Bodies
15
Q
is a structure
that completely
surrounds the cell
protoplast.
A
Cell wall
16
Q
WHO developed the stain in 1884?
A
Christian Gram
17
Q
_____ cell wall is thick homogeneous monolayer
* _______ cell wall is thin heterogeneous multilayer
A
Gram-positive
Gram-negative
18
Q
: space between the plasma membrane and the outer membrane (Gram negative bacteria)
A
Periplasmic space
19
Q
Bacterial cell walls always
contain ______, which is a
type of peptidoglycan
A
murein
20
Q
Peptidoglycan is made up of
* 2 amino sugars
___________ = G
____________= M
* 4 amino acids
L-alanine = L-ala
D-glutamic acid = D-glu
________________= DAP
D-alanine = D-ala
A
N-acetyl-glucosamine; N- acetylmuramic acid
diaminopimelic acid
21
Q
_____prevents
formation of this
Interpeptide bond
______breaks this
glycoside bond between
M and G
A
Penicillin
Lysozyme
22
Q
Gram-positive cell walls contain _____ which are thought to stabilize the
Gram positive cell wall and may be used in adherence
A
teichoic acids
23
Gram-negative cell walls include an ________
outer membrane
24
Outer membrane of Gram-negatives has two important properties
1. It protects the cells from ___by many substances
including penicillin and lysozyme.
2. It is the location of ________ (endotoxin) which is
toxic for animals.
permeability
lipopolysaccharide
25
* react with the Gram stain to appear purple,
* cell wall consists of
several layer of peptidoglycan units
* In addition, the cell wall
contains teichoic acid, which consists of glycerol or ribitol and phosphate
Gram positive bacteria
26
Gram ___?
* only single layer of peptidoglycan, connected to a lipoprotein
unit (Braun’s lipoprotein)
* Outer membrane -________
–__________
* two sugar units connected to a hydroxy fatty acid
* referred as an endotoxin since it is toxic in a host's
bloodstream or gastrointestinal tract
– ___________
* consists of sugar molecules
* the primary site recognized by antibodies
Gram negative
lipopolysaccharide
Lipid A portion
O-antigen subunit
27
Gram Staining Procedure
1. ________. Primary stain. Both gram-positive and gram-negative bacteria
become directly stained and appear purple after this step.
crystal violet
28
2. gram's _____. Mordant. This allows the stain to be retained better
by forming an insoluble crystal violet-iodine complex. Both gram-positive
and gram-negative bacteria remain purple after this step.
iodine solution
29
3. ethyl alcohol. _________. This is the differential step. Gram-positive
bacteria retain the crystal violet-iodine complex while gram-negative are
decolorized.
Decolorizer
30
4. ____ (also a basic dye). counterstain Since the gram-positive bacteria are
already stained purple, they are not affected by the counterstain. Gramnegative bacteria, that are now colorless, become directly stained by it.
safranin
30
GRAM STAIN IS NOT
APPLICABLE on
* ________
– Lack cell walls
– Sterols in plasma membrane
* ________
– Wall-less, or
– Walls of pseudomurein (lack NAM and D amino
acids)
Mycoplasmas
Archaea
31
______: attacks PG by hydrolyzing the bonds that
connect NAM and NAG
– _______: inhibits PG synthesis
Lysozyme
Penicillin
32
THE __________
* Contains both proteins and lipids (proportions
vary widely)
* Lipids are ________(with polar and nonpolar ends)
PLASMA MEMBRANE
amphipathic
33
* _______
– Lacks sterols (cholesterols) instead
hopanoids to stabilize bacterial membranes
* _________
–Have a monolayer with lipid molecules
spanning the whole membrane
BACTERIA
ARCHAEBACTERIA
34
THE FLUID MOSAIC MODEL
* By S_______ and _______
. Jonathan Singer; Garth Nicholson
35
two types of membrane proteins
– ______ proteins
* Loosely connected to the membranes and can easily be
removed
* Soluble in aqueous solutions
* 20-30% of total membrane proteins
– _______proteins (amphipatic)
* 70-80% of total membrane proteins
* Not easily extracted from membranes
* Insoluble in aqueous solutions when freed of lipids
Peripheral
Integral
36
* ____
– Ester linkage
–Weaker linkage
* _______
– Ether linkage
– Stronger linkage
EUBACTERIA
ARCHAEBACTERIA
37
POINT OF LINKAGE = POINT OF _____
BREAKDOWN
38
PHOTOSYNTHETIC MEMBRANES:
________
* may be part of the PM or close to it
* in green sulfur bacteria
* lie close or under the PM (w/c contains
enzymes and proteins needed for
photosynthesis) but not continuous with it
chlorosomes
39
PHOTOSYNTHETIC MEMBRANES:
________
* in purple non-sulfur bacteria
* continuous with PM
chromatophore
40
PHOTOSYNTHETIC MEMBRANES:
_______
* may be part of the PM or close to it
–Example: in purple sulfur bacteria
* gives surface area
* continuous with PM
photosynthetic lamellae
41
INTERNAL MEMBRANE SYSTEM
* Invaginations of the plasma membrane in the
shape of vesicles, tubules or lamellae
* Present in both Gram positive and Gram negative
bacteria (generally prominent in Gram +)
The Mesosomes
42
* Paracrystalline surface layer
* common cell wall layer among
Archaea and some Gram positive
* composed of interlocking proteins /
glycoproteins
* Resistant to penicillin and lysozyme
* Functions:
– protection against ion and pH
fluctuations, and osmotic stress,
predaceous bacteria
– selective sieve: allows passage f lowmolecular-weight and excluding large
molecules and structures
– retain proteins near the cell surface
THE S LAYER
43
* Outside cell wall
* Usually sticky
* Extracellular polysaccharide
* Slime layer and capsule
GLYCOCALYX
44
* _________
– Network of polysaccharides extending from the
surface of bacteria
– Encompass both capsules and slime layers
* ________
– Well-organized layer, not easily washed-off
* ______
– Diffuse, unorganized material, easily removed
GLYCOCALYX
CAPSULE
SLIME LAYER
45
FUNCTIONS OF GLYCOCALYX
* ___________
– contributes to bacterial virulence (degree to which it can cause
disease)
* pathogenic-encapsulated
* protein and polysaccharide-difficult to digest
protection from phagocytosis
46
*_________
– water can’t escape
protection from dessication
47
* ___________
– in the intestine; can reproduce
adherence to surfaces
48
* __________
– in the mouth; adheres to the teeth
– if no food available, glycocalyx will be utilized
source of nutrition
48
* _______
– Short, fine, hair-like appendages thinner than flagella
not involved in motility
– Visible using EM
– Composed of helically arranged protein subunits
– May be used for attachment to surfaces or host
FIMBRIAE (fimbria)
49
* __________
– Also called sex pilus, Larger than fimbriae
– Genetically determined by sex factors or conjugative
plasmids
– Required for bacterial mating
PILI (pilus)
50
* ________
– Threadlike locomotor appendages
extending outward from the plasma
membrane and cell wall
– helical protein filaments responsible for
rapid free-swimming motility
FLAGELLA
51
4 arrangements of flagella are used for
identification of bacteria
– _________: 1 flagella at one end
– _________: both sides of flagella
– __________: path of flagella at one end;
– __________: all over the surface; around;
Monotrichous
Amphitrichous
Lopotrichous
Peritrichous
52
* 3 PARTS
– _______
* Longest and most obvious, extends
from the cell surface to the tip
– _________
* Embedded in the cell
– _______
* Short, curved segment, links filament
to its basal body
* _______
– Protein subunits of filament (MW
= 30, 000 - 60, 000)
FILAMENT
BASAL BODY
HOOK
Flagellin
53
* for gliding or spiral motion; unique to spirochetes
AXIAL FILAMENT
54
* a sprecial resistant, dormant structure formed internal to
the plasma membrane by certain G+ bacteria
* highly refractile structure can be seen; no need for
staining in brightfield microscopy
* resistant to freezing temperature, heat, UV, radiation,
dessication, chemical disinfectants
* some may remain viable for hundred or thousands or even
millions of years
* formed when essential nutrients become depleted
BACTERIAL ENDOSPORE
55
PARTS OF AN ENDOSPORE
* ________
– Thin delicate covering
* ________
– Lies beneath exosporium; fairly thick
– Composed of several protein layers
– Impermeable and resistant to
chemicals
EXOSPORIUM
SPORE COAT
56
PARTS OF AN ENDOSPORE
* _________
* Inside the cortex
* Surrounds the protoplast or core
* _______
* Has the normal cell structure such
as ribosomes and nucleoid
SPORE CELL WALL
CORE
57
PARTS OF AN ENDOSPORE
_________
– Occupies half the spore
volume
– Rests beneath the spore coat
– Made up of PG that is less
cross-linked than vegetative
cel
CORTEX
58
______- endospores can be destroyed
by breaking the spore coat through alternate
heating and cooling
Tyndallization
59
THE ______
* Substance lying between the plasma membrane
and the nucleoid
* Largely water (about 70%)
* Often packed with ribosomes
* Protoplast: plasma membrane + everything
within
– ________ is a major part of the protoplast
CYTOPLASMIC MATRIX
60
______
* Example: volutin
– Corynebacterium diptheriae
* turns red if you use blue dye
* represent reserves of inorganic phosphate used
in ATP synthesis
* found also in algae, fungi, and protozoans
METACHROMATIC GRANULES
61
__________
* common lipid storage is PHB (poly- -
hydroxybutyric acid)
* detected by Sudan dyes
* ex. Mycobacterium, Bacillus, Azotobacter,
Spirillum
LIPID INCLUSIONS
62
_________
* contain the enzyme RDP carboxylase
* used by bacteria in CO2
fixation during
photosynthesis
* Example: Nitrifying bacteria, cyanobacteria,
Thiobacillus
CARBOXYSOMES
63
_____
* Gas vesicles
* hollow cavities found in aquatic prokaryotres,
cyanobacteria, anoxygenic photosynthesizers
and halobacteria
* maintain buoyancy of aquatic cells
GAS VACUOLES
64
_____________
* inclusions of iron oxides (Fe3O4
) found in some Gbacteria such as Aquaspirillum magnetotacticum that
act like magnets
* used by bacteria to orient themselves in the earth’s
magnetic field
* used to determine
northward and downward directions, and swim down
to nutrient rich sediments or locate the optimum
depth in freshwater and marine habitats
MAGNETOSOMES
65
Nucleoid contains small, circular
DNA molecules called
________, believed to be
associated with
membrane proteins
PLASMIDS
66
* ________
– A bacterial or fungal cell with its cell wall completely
removed; spherical; osmotically sensitive
* ________
– A relatively spherical cell formed by weakening or partial
removal of the rigid cell wall component (e.g. penicillin
treatment); osmotically sensitive
* ______
– Pleiomorphic bacterial cells formed by the complete or
partial loss of their cell walls; cell wall loss may be
reversible or permanent
Protoplasts
Spheroplasts
L-forms
67
Ribosomes
* ____
– Membrane-bound
– Free; Attached to ER In cytoplasm
* ____
– In chloroplasts and mitochondria
80S
70S
68
* _________
– consists of glycogen and starch
– glycogen granules turn reddish brown and starch
appear blue with iodine
* __________
– also present in heads of birds, tuna, dolphins, and
green turtles
– two kinds: magnetite: Fe3O4
gregite: Fe3
S4
polysaccharide granules
Magnetosomes
