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Microbiology Lecture Slides > Bacterial Structure > Flashcards

Bacterial Structure Flashcards

1
Q

Lack a nuclear membrane

A

Prokaryotes

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2
Q

Bacteria divide by

A

Transverse fission

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3
Q

Bacterial multiplication is fast. Each division cycle can be as short as

A

20 minutes

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4
Q

Rod-shaped bacteria are the

A

Bacilli

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5
Q

Spherical shaped bacteria are the

A

Cocci

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6
Q

What are the two actin homologues that are required for chromosome/plasmid segregation?

A

mreB and parM

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7
Q

mreB and parM form which types of filaments?

A

Helical or double-helical

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8
Q

A major target for anti-bacterial drugs

-has three layers

A

Bacterial envelope

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9
Q

What are the three layers of the bacterial envelope?

A
  1. ) Plasma membrane
  2. ) Cell wall
  3. ) Structures outside wall
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10
Q

The bacterial plasma membrane is made up of a

A

Lipid bilayer with proteins

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11
Q

Functions in the import and export of solutes

A

Bacterial plasma membrane

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12
Q

The bacterial plasma membrane has complexes of respiratory chain that are the equivalent of the

A

Inner mitochondrial membrane

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13
Q

The bacterial cell wall is made up of a long-chain or polysaccharide with peptide cross-links. This material is called

A

Peptidoglycan

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14
Q

The bacterial cell wall is essential to the integrity of the bacterial envelope. Damage to the cell was leads to

A

Osmotic lysis

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15
Q

Has no equivalent in mammalian cells, so antibiotics that target it have excellent selective toxicity

A

Bacterial cell wall

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16
Q

What type of receptors are commonly found in the bacterial cell wall?

A

Toll-like receptors

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17
Q

Disaccharide + peptide units assembled in cytosol on lipid carrier

A

Peptidoglycan

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18
Q

Peptidoglycan is assembled in the

-on a lipid carrier

A

Cytosol

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19
Q

The disaccharide/peptide units of peptidoglycan that had been assembled in the cytosol are transported across the

A

Plasma membrane

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20
Q

Here we see the disaccharides assembled into long chains and the chains are then cross-linked by

-essential for strength of wall

A

Peptide bonds

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21
Q

A structural analogue of the D-ala-D-ala of peptidoglycan side chains

A

Penicillin

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22
Q

Binds active site of cross-linking enzyme and forms irreversible covalent bond, inactivating the enzyme

A

Penicillin

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23
Q

Penicillin results in new peptidoglycan being formed without

A

Cross-links

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24
Q

Penicillin action requires new peptidoglycan formation so it acts best on

A

Growing cells

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25
Q

Differences in peptidoglycan thickness cause bacterial cells to stain differently. We call this the

A

Gram stain

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26
Q

The first step in identifying the bacteria is the

A

Gram stain

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27
Q

Thick peptidoglycan, i.e. 20-50 layers

A

Gram-positive (blue/purple)

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28
Q

Thin peptidoglycan, i.e. 1-3 layers

A

Gram negative (red/pink)

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29
Q

Retains more dye

A

Thick peptidoglycan

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30
Q

What are the 4 characteristics of the envelopes of gram-positive bacteria?

A

Thick peptidoglycan, protein fibrillae, teichoic acids, and group carbohydrates

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31
Q

Adhere to mammalian cells and extracellular matrix;

-many types per cell

A

Protein fibrillae

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32
Q

Polymers of sugar alcohols linked by phosphate groups

A

Teichoic acids

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33
Q

Teichoic acids are unique to

A

Gram-positive bacteria

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34
Q

Linked to peptidoglycan

–in some groups, important in identification

A

Group Carbohydrates

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35
Q

Bind membrane proteins of mammalian cells

A

Protein Fibrillae

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36
Q

In EM, protein fibrillae appear as?

A

Fuzz on cell surface

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37
Q

Protein fibrillae are covalently linked to

A

Peptidoglycan

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38
Q

Essential to virulence and serve as a potential target of anti-biotics

A

Protein fibrillae

39
Q

What are the four components of the bacterial envelopes of gram-negative bacteria?

A

Plasma membrane, thin peptidoglycan, outer membrane, and periplasm

40
Q

Serves as a second membrane (lipid bilayer/protein) that is outside of the peptidoglycan

A

Outer membrane of gram-negatives

41
Q

Space between outer and inner (plasma) membranes

A

Periplasm

42
Q

Filled with enzymes, solute carrier proteins, polysaccharides

-Not an empty space

A

Periplasm

43
Q

Protein assemblies traverse the periplasm and link

A

Inner and outer membranes

44
Q

The inner leaflet of the outer membrane of gram negative bacteria has typical

A

Phospholipids

45
Q

The outer leaflet of the outer membrane of gram negative bacteria on the other hand is composed lost entirely of

A

Lipopolysccharide (LPS)

46
Q

The fatty acids in the outer membrane are tightly packed and are

A

Saturated FAs

47
Q

The outer membrane is HIGHLY

-major defense against toxic small molecules

A

Impermeable

48
Q

Allow solutes to traverse the outer membrane

A

Porin proteins

49
Q

A trimer

A

Porin protein

50
Q

Each monomer of this protein is a cylinder made up of walls of beta sheet

A

Porin protein

51
Q

The exterior of a porin cylinder is covered with

A

Hydrophobic amino acids

52
Q

This allows porin to be embedded in the lipid bilayer of the

A

Outer membrane

53
Q

The interior of the porin cylinder is lined with

-serves as the “pore” for diffusion of solutes

A

Hydrophilic amino acids

54
Q

Determines the ability of antibiotics to enter the cell

A

The pore diameter

55
Q

LPS is on the outer leaflet of the outer membrane and is composed of which three parts?

A
  1. ) O-antigen
  2. ) Core
  3. ) Lipid A
56
Q

A polymer made up of repeating units of 3-5 sugars

A

O-antigen

57
Q

A phosphorylated, complex oligosaccharide

A

LPS core

58
Q

A disaccharide + 6-8 saturated fatty acids

A

Lipid A

59
Q

Te length of the O-antigen varies with

A

Species

60
Q

Helps bacteria to evade the immune system

-some species change the antigenic structure

A

O-antigen

61
Q

The length of the O-antigen diverts the

A

MAC of complement

62
Q

Lipid A is a disaccharide with 6-8 saturated fatty acids. It has a toxic portion that is called the

A

Endotoxin

63
Q

Integral portion of the cell wall of gram-negative bacteria that is released only when the cell lyses

-The toxic poriton

A

Lipid A

64
Q

The LPS receptors on monocytes are

A

Toll-like receptors

65
Q

LPS binding to TLR leads to the synthesis and release of

A

Inflammatory cytokines

66
Q

Can cause septicemia and produce septic shock

-can also result in DIC

A

Lipid A (toxic to body)

67
Q

Bacteria in the bloodstream

A

Septicemia

68
Q

Present in both living and dead bacteria, and is not removed by sterilization

A

Lipid A (Endotoxin)

69
Q

Must be removed from materials before parenteral use

A

Endotoxin

70
Q

Kills bacteria, but can result in release of endotoxin and other inflammatory components

A

Antibiotic treatment

71
Q

The release of endotoxin and other inflammatory components can then create

A

Fever and hypotension

72
Q

What are the three types of bacterial appendages?

A

Flagella, Pili, and conjugated pili

73
Q

Function in locomotion (H antigen)

A

Flagella

74
Q

Function in adhesion

A

Pili (fimbrae)

75
Q

Function in the transfer of DNA between cells

A

Conjugation Pili

76
Q

Bacteria is propelled through medium by

A

Rotation of flagella

77
Q

The basal body of the flagella rotates in the bacterial envelope. This is driven by

A

H+ Inflow

78
Q

The H+ inflow causes rotation of the flagellum, which then

A

Propels the cell

79
Q

Enable bacteria to adhere to mammalian cells or to eachother

A

Pili

80
Q

Special organelles for DNA transfer

A

Conjugation pili

81
Q

Protect bacteria from phagocytes

A

Capsules

82
Q

Made up of K antigen, which is mostly high MW polysaccharides

A

Capsules

83
Q

Not visible in Gram-stain, and requires a special stain or EM?

A

Bacterial capsules

84
Q

Specialized cells for dispersal, resisting unfavorable environments

A

Bacterial spores

85
Q

Made up of thick walls and are metabolically inert

-omnipresent in soil and plant material

A

Bacterial spores

86
Q

Bacterial spores are resistant to

-require autoclave for sterilization

A

Boiling

87
Q

Bacterial spores are formed in response to starvation, and are made by only some

A

Gram-positive Rods

88
Q

Are highly refractile, but do not Gram-stain because of the thickness of their walls

A

Spores

89
Q

Bacteria change the direction of their swimming by reversing direction in which their

A

Flagella Rotate

90
Q

Smooth swimming is the result of

A

Counter-clockwise rotation

91
Q

Random tumbling is the result of

A

Clockwise rotation

92
Q

When swimming up a concentration gradient of attractant, we see the suppression of

A

Tumbling

93
Q

When swimming down the concentration gradient we see promotion of

A

Tumbling and re-orientation

Microbiology Lecture Slides (24 decks)

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