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MCB > Lec 3 > Flashcards

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)

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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

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3
Q
  • ________
    microscopy uses a
    metal probe to scan a
    specimen
  • Resolution 1/100 of an
    atom
A

SCANNING TUNNELING MICROSCOPY

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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

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5
Q

Most bacteria are ______
* A few are pleomorphic

A

monomorphic

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6
Q

VARIOUS ARANGEMENTS
Pairs: _________
* Clusters: _______
* Chains: ____________

A

diplococci, diplobacilli
staphylococci
streptococci, streptobacilli

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7
Q

Largest prokaryotic cell

A

Thiomargarita namibiensis

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8
Q

FUNCTIONS OF PROKARYOTIC
STRUCTURES

Gives bacteria shape and protection from
lysis in dilute solutions

A

Cell Wall

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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

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10
Q

FUNCTIONS OF PROKARYOTIC
STRUCTURES

Resistance to phagocytosis,
adherence to surfaces

A

Capsules and Slime Layers

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10
Q

FUNCTIONS OF PROKARYOTIC
STRUCTURES

Attachment to surfaces,
bacterial mating

A

Fimbriae and Pili

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10
Q

FUNCTIONS OF PROKARYOTIC
STRUCTURES

Survival under harsh
environmental conditions

A

Endospore

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11
Q

Localization of Genetic Material
(DNA)

A

Nucleoid

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12
Q

Contains hydrolytic enzymes and
binding proteins for nutrient
processing and uptake

A

Periplasmic
Space

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13
Q

Buoyancy for floating in aquatic
environments

A

Gas Vacuole

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14
Q

Storage of carbon, phosphate and other
substances

A

Inclusion Bodies

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15
Q

is a structure
that completely
surrounds the cell
protoplast.

A

Cell wall

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16
Q

WHO developed the stain in 1884?

A

Christian Gram

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17
Q

_____ cell wall is thick homogeneous monolayer
* _______ cell wall is thin heterogeneous multilayer

A

Gram-positive
Gram-negative

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18
Q

: space between the plasma membrane and the outer membrane (Gram negative bacteria)

A

Periplasmic space

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19
Q

Bacterial cell walls always
contain ______, which is a
type of peptidoglycan

A

murein

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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

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21
Q

_____prevents
formation of this
Interpeptide bond

______breaks this
glycoside bond between
M and G

A

Penicillin
Lysozyme

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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

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23
Q

Gram-negative cell walls include an ________

A

outer membrane

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24
Q

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.

A

permeability
lipopolysaccharide

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25
Q
  • 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
A

Gram positive bacteria

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26
Q

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

A

Gram negative
lipopolysaccharide
Lipid A portion
O-antigen subunit

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27
Q

Gram Staining Procedure
1. ________. Primary stain. Both gram-positive and gram-negative bacteria
become directly stained and appear purple after this step.

A

crystal violet

28
Q
  1. 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.
A

iodine solution

29
Q
  1. ethyl alcohol. _________. This is the differential step. Gram-positive
    bacteria retain the crystal violet-iodine complex while gram-negative are
    decolorized.
A

Decolorizer

30
Q
  1. ____ (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.
A

safranin

30
Q

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)

A

Mycoplasmas
Archaea

31
Q

______: attacks PG by hydrolyzing the bonds that
connect NAM and NAG
– _______: inhibits PG synthesis

A

Lysozyme
Penicillin

32
Q

THE __________
* Contains both proteins and lipids (proportions
vary widely)
* Lipids are ________(with polar and nonpolar ends)

A

PLASMA MEMBRANE
amphipathic

33
Q
  • _______
    – Lacks sterols (cholesterols) instead
    hopanoids to stabilize bacterial membranes
  • _________
    –Have a monolayer with lipid molecules
    spanning the whole membrane
A

BACTERIA
ARCHAEBACTERIA

34
Q

THE FLUID MOSAIC MODEL
* By S_______ and _______

A

. Jonathan Singer; Garth Nicholson

35
Q

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

A

Peripheral
Integral

36
Q
  • ____
    – Ester linkage
    –Weaker linkage
  • _______
    – Ether linkage
    – Stronger linkage
A

EUBACTERIA
ARCHAEBACTERIA

37
Q

POINT OF LINKAGE = POINT OF _____

A

BREAKDOWN

38
Q

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

A

chlorosomes

39
Q

PHOTOSYNTHETIC MEMBRANES:
________
* in purple non-sulfur bacteria
* continuous with PM

A

chromatophore

40
Q

PHOTOSYNTHETIC MEMBRANES:
_______
* may be part of the PM or close to it
–Example: in purple sulfur bacteria
* gives  surface area
* continuous with PM

A

photosynthetic lamellae

41
Q

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 +)

A

The Mesosomes

42
Q
  • 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
A

THE S LAYER

43
Q
  • Outside cell wall
  • Usually sticky
  • Extracellular polysaccharide
  • Slime layer and capsule
A

GLYCOCALYX

44
Q
  • _________
    – 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
A

GLYCOCALYX
CAPSULE
SLIME LAYER

45
Q

FUNCTIONS OF GLYCOCALYX
* ___________
– contributes to bacterial virulence (degree to which it can cause
disease)
* pathogenic-encapsulated
* protein and polysaccharide-difficult to digest

A

protection from phagocytosis

46
Q

*_________
– water can’t escape

A

protection from dessication

47
Q
  • ___________
    – in the intestine; can reproduce
A

adherence to surfaces

48
Q
  • __________
    – in the mouth; adheres to the teeth
    – if no food available, glycocalyx will be utilized
A

source of nutrition

48
Q
  • _______
    – 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
A

FIMBRIAE (fimbria)

49
Q
  • __________
    – Also called sex pilus, Larger than fimbriae
    – Genetically determined by sex factors or conjugative
    plasmids
    – Required for bacterial mating
A

PILI (pilus)

50
Q
  • ________
    – Threadlike locomotor appendages
    extending outward from the plasma
    membrane and cell wall
    – helical protein filaments responsible for
    rapid free-swimming motility
A

FLAGELLA

51
Q

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;

A

Monotrichous
Amphitrichous
Lopotrichous
Peritrichous

52
Q
  • 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)
A

FILAMENT
BASAL BODY
HOOK
Flagellin

53
Q
  • for gliding or spiral motion; unique to spirochetes
A

AXIAL FILAMENT

54
Q
  • 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
A

BACTERIAL ENDOSPORE

55
Q

PARTS OF AN ENDOSPORE
* ________
– Thin delicate covering

  • ________
    – Lies beneath exosporium; fairly thick
    – Composed of several protein layers
    – Impermeable and resistant to
    chemicals
A

EXOSPORIUM
SPORE COAT

56
Q

PARTS OF AN ENDOSPORE
* _________
* Inside the cortex
* Surrounds the protoplast or core
* _______
* Has the normal cell structure such
as ribosomes and nucleoid

A

SPORE CELL WALL
CORE

57
Q

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

A

CORTEX

58
Q

______- endospores can be destroyed
by breaking the spore coat through alternate
heating and cooling

A

Tyndallization

59
Q

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

A

CYTOPLASMIC MATRIX

60
Q

______
* 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

A

METACHROMATIC GRANULES

61
Q

__________
* common lipid storage is PHB (poly- -
hydroxybutyric acid)
* detected by Sudan dyes
* ex. Mycobacterium, Bacillus, Azotobacter,
Spirillum

A

LIPID INCLUSIONS

62
Q

_________
* contain the enzyme RDP carboxylase
* used by bacteria in CO2
fixation during
photosynthesis
* Example: Nitrifying bacteria, cyanobacteria,
Thiobacillus

A

CARBOXYSOMES

63
Q

_____
* Gas vesicles
* hollow cavities found in aquatic prokaryotres,
cyanobacteria, anoxygenic photosynthesizers
and halobacteria
* maintain buoyancy of aquatic cells

A

GAS VACUOLES

64
Q

_____________
* 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

A

MAGNETOSOMES

65
Q

Nucleoid contains small, circular
DNA molecules called
________, believed to be
associated with
membrane proteins

A

PLASMIDS

66
Q
  • ________
    – 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
A

Protoplasts
Spheroplasts
L-forms

67
Q

Ribosomes
* ____
– Membrane-bound
– Free; Attached to ER In cytoplasm
* ____
– In chloroplasts and mitochondria

A

80S
70S

68
Q
  • _________
    – 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
A

polysaccharide granules
Magnetosomes

MCB (6 decks)

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