Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Infectious Agents > Exam 1: Bacterial Cell Structures > Flashcards

Exam 1: Bacterial Cell Structures Flashcards

1
Q

What are the 2 classes of cell envelope?

A

Gram-positive and gram-negative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the classification of the cell envelope based on?

A

The ability of a species to retain a crystal violet-iodine stain when treated with organic solvents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What does the staining property of the cell envelope depend on?

A

The morphology and composition of the bacterial envelope

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the gram-positive envelope structure?

A

Cell membrane: phospholipid bilayer similar to eukaryotic membranes
Cell wall: located outside cell membrane. Thick peptidoglycan layer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the gram-negative envelope structure?

A

Inner membrane: phospholipid bilayer similar to gram-positive cell membrane and eukaryotic membranes
Cell wall: peptidoglycan layer that is much thinner that gram-positive cell wall
Outer membrane: inner leaflet is phospholipid, but outer leaflet is a unique bacterial structure- lipopolysaccharide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Look at photo with differences between gram negative and gram positive

A

Look at photo with differences between gram negative and gram positive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What occurs due to gram-positive bacteria having a thicker cell wall?

A

They have an increased resistance to mechanical, heat or drying damage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What occurs due to gram-negative bacteria having the presence of the outer membrane?

A

The envelope is more impermeable, especially to hydrophilic compounds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What does the more impermeable membrane of gram-negative do?

A

Makes the bacteria less susceptible to many toxic compounds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is periplasm?

A

An extra compartment between the inner and outer membranes of gram-negative bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How much of the cell volume is periplasmic compartment?

A

20-40%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What does the periplasmic compartment contain?

A

The cell wall and a gel-like solution of proteins that facilitate nutrition and inactivate toxic compounds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What does the periplasmic space allow?

A

Concentration of detoxifying enzymes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

In gram-positive bacteria, where are the detoxifying antibodies secreted?

A

Into surrounding membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the cell membrane?

A

An osmotic barrier modified by the presence of specific transport systems

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What makes up the cell membrane?

A

Phospholipid bilayers that lacks sterols

Embedded membrane proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the embedded membrane proteins?

A

Specific transport systems for secretion and uptake

Macromolecular synthesis/secretion proteins, such as cell wall Metabolic proteins: electron transport system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the cell membrane the site of?

A

Action of some disinfectants and detergents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What does peptidoglycan (cell wall) do?

A

Imparts cell shape and allows bacteria to survive in hypotonic solution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is peptidoglycan?

A

The basic layer just outside the cell membrane in all eubcteria except Mycoplasma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is peptidoglycan composed of?

A

A complex polymer forming concentric sheets

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Is peptidoglycan thicker in gram-positive or gram-negative?

A

Gram-positive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is peptidoglycan the site of action for?

A

Lysozyme and lysostaphin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is a special component of gram-positive cell walls?

A

Teichoic/lipoteichoic acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Describe teichoic/lipoteichoic acids

A

Attached to peptidoglycan or anchored in the cytoplasmic membrane
Can account for up to half of cell wall mass
Species-specific structure
Composed of sugar backbone with side groups
Highly antigenic and useful as taxonomic markers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What are the 3 parts to peptidoglycan?

A

Backbone: alternating NAG and NAM monomers
Side chains: tetrapeptides attached to NAM
Crosslinkages: Linked side chains from peptides from different backbone units

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What are the tetrapeptides attached to NAM?

A

D-alanine, L-alanine, D-glutamic acid, and L-lysine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What are crosslinkages the site of?

A

Penicillin action

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

How are gram-negative side chains linked?

A

Directly by interpeptide bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What are side chains like in many gram-positive bacteria?

A

They are crosslinked by an interpeptide bridge of amino acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What do lipoproteins do?

A

Attach cell wall to outer membrane of gram-negative bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What do the outer membrane proteins include of gram-negative bacteria?

A

Porins that allow nutrients to pass through

Many proteins involved in host-pathogen interaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is the inner leaflet of gram-negative bacteria made of?

A

Phospholipids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is lipopolysaccharide?

A

Highly antigenic, species-specific and sometimes subspecies-specific structure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What does LPS induce?

A

A toxic response in mammals when release from lysed cells; hence it is also referred to as endotoxin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What are the 3 components of the unique bacterial structure of LPS?

A 
Lipid A
Core oligosaccharide
O polysaccharide (O side chain or O antigen)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What is lipid A?

A

Hydrophobic portion that interacts with phospholipids inner leaflet
This is the toxic portion of LPS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What is core oligosaccharide?

A

Short CHO chain attached to lipid A

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What is O polysaccharide?

A

Long hydrophilic CHO chain attached to core oligosaccharide that covers the bacterial surface
This is thee antigenic and serotype-specific structure of LPS

40
Q

Where are capsules or slime layers?

A

Located outside the cell wall or outer membrane

41
Q

What are capsules or slime layers?

A

Amorphous CHO polymers that vary widely from species to species in sugar composition and structure; often highly species or subspecies specific

42
Q

What is the slime layer, more specifically?

A

The polymer that is loosely associated and continuously shed

43
Q

What is the antigen involved with capsules?

A

K antigen

44
Q

What are capsules and slime layers useful in? Why?

A

Serotyping and as vaccine antigens

They are immunogenic

45
Q

What do capsules proivde?

A

An extra layer of protection for some bacteria by preventing lysosomal enzyme hydrolysis or complement-mediated lysis

46
Q

In some bacteria, what can capsules serve as?

A

Adhesins, allowing adherence to epithelial surfaces

47
Q

How are some capsules produced?

A

Only under certain conditions including in vivo

48
Q

In some bacteria, what are capsules highly similar to?

A

The O polysaccharide

49
Q

Describe the structure of Mycobacterium spp.

A

Gram-positive cell envelope structure, but cell wall contains mycolic acid and a large amount of lipids, which are complex, long-chain hydrocarbons substituted with sugars and other modifying groups

50
Q

What does the acid-fast bacterial cell wall serve as?

A

A waxy, protective cover making them nearly impervious to many harsh chemicals

51
Q

What do acid-fast bacterial cell walls prevent?

A

Penetration of gram stain reagents unless bacteria are pretreated with heat or a detergent

52
Q

Why are acid-fast bacteria very slow growing?

A

The waxy coat causes slow uptake of nutrients

53
Q

What is S layer?

A

Present on some fish pathogens

Located outside the cell wall or outer membrane

54
Q

Describe S layer

A

Outer layer of protein subunits arranged in a crystalline array; usually a single king of protein molecule capable of self assembly
Resistant to proteolystic enxymes and protein-denaturing agents
Helps protect against phagocytosis and may participate in adherence to surfaces

55
Q

What does the chlamydia cell envelope resemble?

A

The gram-negative envelope except they have no peptidoglycan layer

56
Q

What does Chlamydia have instead of peptide crosslinkages?

A

A network of disulfied bonds among envelope proteins imparts rigidity to the chlamydial cell envelope

57
Q

Describe Mycoplasma

A

Lack peptidoglycan cells wall; therefore, they are susceptible to osmotic lysis

58
Q

What does the cytoplasm consist of?

A

A basic-staining, densely packed granular region surrounding an amorphous, less dense nuclear region

59
Q

What is a chromosome?

A

Naked DNA

60
Q

What is DNA of bacteria like?

A

Usually a circular, covalently closed double-stranded molecule

61
Q

How many base pairs are in an E. coli chromosome? Protein coding genes?

A

4.6 million

4288

62
Q

How does a chromosome fit inside the bacteria cell?

A

It is highly supercoiled

63
Q

What is a plasmid?

A

Smaller, accessory DNA molecules that replicated independently of the chromosome

64
Q

What can plasmids sometimes be transferred between?

A

Bacterial cells

65
Q

What do plasmids often carry?

A

Genes that confer a selective advantage under certain conditions (antibiotic resistance genes)

66
Q

What are ribosomes?

A

Protein translation machinery

67
Q

What gives the cytosol the granular appearance?

A

Dense packing of ribosomes

68
Q

What is the structure of prokaryotic ribosomes?

A

70S, which can be dissociated into 50S and 30S subunits

69
Q

What is used for classification of ribosomes?

A

16S

70
Q

What is a polysome?

A

More than one ribosome can attach to a single mRNA strand

71
Q

What is the target of several antibiotic classes?

A

Ribosomes

72
Q

What allows ribosomes to be the target of several antibiotic classes?

A

The structural differences between prokaryotic and eukaryotic ribosomes

73
Q

What is flagellum?

A

Organ of bacterial locomotion

Helical filament that is driven by a motor at its base

74
Q

How does flagella rotate?

A

Relative to the bacterial surface to propel bacteria through the medium

75
Q

What is the bacterial flagella like compared to eukaryotic flagella?

A

Bacteria is more rigid. Motion is by rotation only

76
Q

What is monotrichous flagellum?

A

Has a single, polar flagellum (Vibrio cholerae)

77
Q

What is peritrichous flagellum?

A

Has multiple flagella over their surface (E. coli)

78
Q

What are the 3 parts of flagellum?

A

Filament
Hook
Basal body

79
Q

What is the filament of flagellum?

A

Long, helical outermost structure extending into medium

Composed of several thousand copies of a single protein called flagellin

80
Q

What are flagellins?

A

Highly antigenic proteins that have high immunologic specificity for H antigens

81
Q

What does the hook do?

A

Connects filament to basal body

82
Q

What does the basal body do?

A

Anchors in membrane, flagellar motor

83
Q

What is the basal body driven by?

A

Protonmotive force (membrane potential)

84
Q

What are attachment pili or fimbriae?

A

Organelles of attachment to surfaces

Hair-like projections extending from cell membrane

85
Q

How many attachment pili/fimbriae does typical E. coli have?

A

100 to 300

86
Q

What is attachment pili/fimbriae composed of?

A

Structural proteins called pilins and adhesin proteins at tip

87
Q

What do adhesin proteins do?

A

Mediate attachment and exhibit remarkable specificity

Often are important virulence factors mediating attachment to host cell or extracellular matrix

88
Q

What are the fimbriae of different bacteria like?

A

Antigenically distinct, so specific host antibodies can block attachment

89
Q

What is conjugative pili?

A

Specialized organelles of plasmid DNA during conjugation (bacterial mating)
Hollow tube connective 2 bacteria through which DNA is transferred

90
Q

What can happen with antimicrobial resistance with a conjugative pili?

A

It can move from one bacteria to another

91
Q

Describe endospores

A

Resting stag with high resistance to heat
They are dehydrated cells composed of 5-15% calcium dipicolinate covered by keratin-like protein
Extremely low metabolic activity, can survive for years in this state

92
Q

What is the most resistance form of life known?

A

Endospores

93
Q

What are L-forms?

A

A bacteria that lack a cell was the occurs spontaneously

94
Q

Where may L-forms occur?

A

In vivo

95
Q

What may L-forms be associated with?

A

Antibiotic resistance

96
Q

What can induce formation of L-forms?

A

Special media with high osmolarity

Infectious Agents (38 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions