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Bacterial Cell Morphology And Composition > Component Of A Bacteria > Flashcards

Component Of A Bacteria Flashcards

1
Q

What are the components of a bacteria?

A

Cell wall
Plasma membrane
Cytoplasm
Components external to the cell

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2
Q

One of the most important structures
Layer that is usually fairly rigid that lies outside the plasma
membrane

  1. Confers shape
  2. Protects the cell from osmotic lysis
  3. Anchors the flagellum
  4. Adds to the pathogenicity of the cell
  5. Protects the cell from toxic substances and pathogen
  6. Used in identification
A

Cell wall

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3
Q

Why is gram positive violet/blue stain while gram negative is red stain?

A

The peptidoglycan layer enables the differentiation with the gram staining action. In gram positive, the peptidoglycan layer only absorbs the crystal violet stain –giving the violet/bluish color. In gram negative, when the colorizer is applied, because of the very thin peptidoglycan layer, the crystal violet is being washed off. And then, when the counterstain, safranin, which is red in color is applied, it gives off a red stain.

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4
Q

CHARACTERISTICS OF A GRAM POSITIVE (+) CELL WALL

A
  1. Thick layer of peptidoglycan
  2. Presence of Teichoic acid
  3. Other substances found in cell wall
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5
Q

what are the other substances found in cell wall?

A

Teichuronic acid
Neutral polysaccharides
Other glycolipids
Mycolic acids

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6
Q

Refers to the major composition of the cell wall.

A

Peptidoglycan

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7
Q

Peptidoglycan subunit

A

Peptidoglycan subunit:
1. N-acetylglucoseamine (G)
2. N-acetylmuramic acid (M)
3. L-alanine
4. D-glutamic acid
5. D-alanine
6. Meso-diaminopimelic-acid

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8
Q

the one responsible for the gram positivity of microorganism. Because of its presence in the peptidoglycan layer, it retains the crystal violet stain.

A

Teichoic acid

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9
Q

Linear polymers of 16-40 phosphodiester-linked
glycerophosphate residues covalently linked to the cell membrane

A

Lipoteichoic acid (LTA)

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10
Q

These are the
viruses that infects bacteria.

A

Bacteriophages

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11
Q

Periplasmic space in gram (+) and (-)

A

(+) plasma membrane and cell wall
(-) plasma membrane and outer membrane

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12
Q

Characteristics of a gram negative (-) cell wall includes thin layer of peptidoglycan and what outer membranes

A

Lipopolysaccharides (LPS)
Lipoproteins
Porins

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13
Q

Lipopolysaccharides (LPS) contains High toxin.
NOTE: The difference between gram positive and gram negative is:
Gram negative: the LPS would be released after the microorganism is already ______
Gram positive: the LPS is released continuously while the microorganism is_______

A

(+) alive
(-) already dead

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14
Q

3 parts of LPS

A
  1. Lipid A
  2. Core polysaccharide region
  3. O-antigen
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15
Q

In E. coli and Salmonella typhimurium: fatty acids are

A

β-hydroxymyristic acid (3-hydroxytetradecanoic acid)

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16
Q

Composed of 2 glucosamine residues linked β-1,6 (backbone) with four identical fatty acids

A

Lipid A

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17
Q

Inner core of the polysaccharide region consists of

A
  1. 2-keto-3-deoxyoctonate (KDO) 2. Heptose
  2. Ethanolamine
  3. Phosphate
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18
Q

− Short polysaccharide extending outward from the core
− Consists of peculiar sugars which varies between bacterial strains
− NOT essential for viability

A

O-antigen

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19
Q

Importance of Lipopolysaccharides (LPS)

A

 Avoidance of host defenses (O-antigen)
 Contributes to the negative charge on the cell’s
surface.
 Stabilizes membrane structure
 Act as endotoxin

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20
Q

 Mediate interconnection between OM and
murein
 Synthesized within the cell and contains a
leader sequence of 20 amino acids at its amino
terminal end
 After transport through the CM, the leader
sequence is removed and the terminal residue
is modified to make it hydrophobic
 Facilitates integration to the OM

A

Lipoproteins

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21
Q

Small holes in the cell wall

A

Porins

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22
Q

Importance of outer membrane

A

 Proteins in OM are used as attachment sites
by bacteriophages
 Permeability barrier to heavy metals, lipid-
disrupting agents and larger molecules
There are heavy metals that are toxic to the bacteria.
 Outer surface with strong negative charge is important in evading phagocytosis

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23
Q

Space between the cell wall and the peptidoglycan layer (aqueous compartment)

A

Periplasm

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24
Q

Space between the cell wall and the peptidoglycan layer (aqueous compartment)

A

Periplasm

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25
Q

Activities of periplasm

A

 Redox reactions
For transport of materials
 Osmotic regulations
So that limited materials would enter. Otherwise, it would lead to shrinkage or the cell would burst.
 Solute transport  Protein secretion  Hydrolysis

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26
Q

Composition of plasma membrane

A
  1. Phospholipid
  2. Proteins
  3. Hopanoids
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27
Q

In phospholipid, most membrane associated lipids are

A

Structurally asymmetric

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28
Q

Parts of phospholipid

A

Phosphatidylethanolamine
Phosphatidylglycerol
Fatty acids

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29
Q

Major phospholipid in the cytoplasmic membrane

A

Phosphatidylethanolamine

30
Q

Phosphatidylethanolamine is formed from

A

Glycerol-3-P
Serine
Fatty acids
1:1:2

31
Q

Phosphatidylglycerol, next most prevalent is formed from

A

Glycerol-3-P
Serine
Ratio is equimolar

32
Q

Part of phospholipid that varies depending on the species and environmental conditions

A

Fatty acids

33
Q

2 types of proteins

A

A. Integral proteins
B. Peripheral proteins

34
Q

− embedded in the CM
− Amphipathic
− bound to the fatty acids of the phospholipids via hydrophobic bonding

A

Integral proteins

35
Q

− attached to membrane surfaces by ionic
interactions

A

Peripheral proteins

36
Q

− Rigid, planar molecules found associated with
bacterial CM
− Molecules similar to sterol

A

Hopanoids

37
Q

− Most widely accepted model of the CM
− Shows that the CM is a lipid bilayer with which proteins
and lipids “float” freely

A

Fluid Mosaic Model

38
Q

The fatty acid responsible for the fluidity of the cytoplasmic membrane is the

A

unsaturated acids.

39
Q

What is the component of the lipid bilayer?

A

Phosphatidylcholine and phosphatidylethanolamine

40
Q

Prokaryotic cytoskeleton

A

Cresentin
FtsZ
MreB

41
Q

− Invaginations of the plasma membrane in the shape
of vesicles, tubules, or lamellae
− Believed to be involved in:
 cell septum formation electron transport
 photosynthesis
 cell wall formation
 DNA replication
 Segregation and sporulation

A

Mesosomes

42
Q

− Complex structures made of both protein and
ribonucleic acid
− Present in the cytoplasmic matrix or loosely attached
to the plasma membrane
− Site of protein synthesis

A

Ribosomes

43
Q

Characteristics of a bacterial chromosomes

A
  1. Circular
  2. Very tightly-coiled
  3. Histones are absent
44
Q

Granules and Globules

A
  1. Glycogen
  2. Poly- β - hydroxyalkanoates
  3. Cyanophycin granules
  4. Carboxysomes
  5. Chlorosomes
  6. Polyphosphate granules
  7. Sulfur granules
  8. Gas vesicles
  9. Magnetosomes
45
Q

Aids in orienting bacteria in the earth’s magnetic field

A

Magnetosomes

46
Q

− Small, hollow, cylindrical structures composed entirely of a single small protein
− Impermeable to water but freely permeable to gases

A

Gas vesicles

47
Q

− Used to store sulfur temporarily
− Accumulate in the periplasmic space of in special cytoplasmic globules
− Can be found in sulfur bacteria

A

Sulfur granules

48
Q

− Linear polymer of orthophosphates joined by ester bonds
− Functions as storage reservoir for phosphates or as energy reserve
− Can be found in Mycobacterium tuberculosis
or Corynebacterium diphtheriae

A

Polyphosphate granules

49
Q

− Ellipsoidal vesicles where photosynthetic pigments are located
− Attached to the plasma
membrane but not continuous with it
− Can be seen in photosynthetic bacterias.

A

Chlorosomes

50
Q

− Polyhedral bodies about 100 nm in diameter
− Containing the enzyme ribulose-1-5-
bisphosphate
carboxylase
− May serve as site for CO2
fixation

A

Carboxysomes

51
Q

− Composed of large polypeptides containing approximately equal amount equal amount of amino acids arginine and aspartic acid

A

Cyanophycin granules

52
Q

− Also: PHB
− Contains β –hydroxybutyrate molecules joined by ester bonds

A

Poly- β - hydroxyalkanoates

53
Q

− A polymer of glucose units composed of long chains formed by α(1-4)
− Reservoir of food of bacteria

A

Glycogen

54
Q

If it is a photosynthetic bacteria it has

A

Carboxysomes

55
Q

Components of the cell wall

A

Glycocalyx
Pili/Fimbrae

56
Q

Glycocalyx layers

A
  1. Capsule
  2. Slime layer
57
Q

 Well-organized glycocalyx
 Attached firmly to the cell wall  Compact
 Excludes particles like India Ink

A

Capsule

58
Q

 Zone of diffused, unorganized material
 Loose association
 Does not exclude particles

A

Slime layer

59
Q

Importance of glycocalyx

A

 Exclude viruses and most hydrophobic toxic substances
 Protection from physical injury
 Aid attachment to surfaces
 Provide resistance to phagocytes
 Reservoir of stored food
 Prevent desiccation
 Confers pathogenicity
 “Cellular garbage dump”
 Antigenicity

60
Q

− Hair-like structures on the surfaces of prokaryotic cells
− Composed of protein subunits called “pilins”

A

Pili/Fimbrae

61
Q

Types of pili

A

Adhesion pili
Conjugation pili

62
Q

 Involved in attachment of cells to surfaces
 Composed of a single protein
 Major determinant of bacterial virulence up to
1000 per cell

IF THE BACTERIA HAS THIS, THE RATE OF INFECTION IS FAST

A

Adhesion pili

63
Q

 Vehicles for transfer of genetic information
between bacteria
 Composed of phosphoglycoprotein
 About 1 to 10 per cell

A

Conjugation pili

64
Q

− Thread-like locomotor appendages extending outward from the plasma membrane and cell wall
− Slender, rigid structures about 20 nm across and 15-20 μm long
− Rotary structure driven from a motor at the base, with the filament acting as the propeller

A

Bacterial flagella

65
Q

The attachment of flagella is deep in the

A

Plasma membrane

66
Q

The movement of the flagellated microorganisms are so called the

A

“tumbling movement”

67
Q

Filament
 A hollow rigid cylinder constructed if a single protein called

A

Flagellin

68
Q

Types of flagella

A
  1. Monotrichous
  2. Amphitrichous
  3. Lophotrichous
  4. Petrichous
  5. Atrichous
69
Q

found inside the cytoplasm [bailey & scott’s 15th ed]
− A type of dormant cell formed by some groups of bacteria − A cryptobiotic
− Highly resistant to environmental stresses
If they encounter a very harsh environment, they would transform themselves into spores. But not all can be turned to spores. It depends on the species and their genes.
− Formed by vegetative cells in response to environmental signals that indicate a limiting factor for vegetative growth
− A mechanism of survival

A

Bacterial endospore

70
Q

Location of spores

A

Terminal spores
Central spores
Subterminal spores

Bacterial Cell Morphology And Composition (2 decks)

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