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Foundations of Medicine > Week 3 - Microbiology Bacterial Structure > Flashcards

Week 3 - Microbiology Bacterial Structure Flashcards

1
Q

What is a microbe?

A

Can be:

Bacteria (prokaryotic)
Protozoa (eukaryotic)
Fugi (eukaryotic)
Virus (neither pro or eukaryotic)

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2
Q

Eukaryotic vs Prokaryotic:

Chromosome
Chromosome location
Nucleolus
Extrachromosomal DNA
Site of Cellular Respiration
Ribosomes
Locomotion
Pili
A

Single Circular vs Paired Linear
Nucleoid (no membrane) vs Nucleus (membrane present)
Absent vs Present
Plasmid vs Mitochondria and Chloroplast
30S & 50S/70S vs 40S & 60S/80S in cytoplasm (70S in organelles)
Rotating flagella and gliding vs Undulatin gflagella and cilia, and also amoeboid movement
Sex or attachement pili vs Absent

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3
Q

Bacterial Structure

A

Two basic shapes:
Rods and Cocci

Other shapes include:
spirochetes (flexible)
spirillum (rigid)
diplococcidiplobacilli

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4
Q

What are bacterial rods?

A

Rod shaped bacteria

Bacillus

or 2 = diplobacilli

or chains = streptobacilli

or palisades - X, V, or Y figures

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5
Q

What are bacterial cocci?

A

Circular bacteria

Cocci

or 2 diplococci

or chains, clumps, tetrads, cubical

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6
Q

What are spirochete?

A

Flexible

Undulating corkscrew shape

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7
Q

What are Spirillium?

A

RIGID

corkscrew shape

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8
Q

Diplobacilli?

A

Two rod shaped bacteria

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9
Q

Streptobacilli?

A

A chain of rod-shape bacteria

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10
Q

Palisades

A

X, V, or Y shaped bacilli

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11
Q

Cocci

A

Circular bacteria

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12
Q

Spirochete

A

Flexible corkscrew bacteria

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13
Q

Spirillum?

A

Rigid corkscrew bacteria

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14
Q

What are inner workings of bacterial structure?

A

Chromosome (nucleoid)
Mesosome
Plasmid DNA
Ribosomes and Granules

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15
Q

Mesosome

A

Chromosomal DNA attached to the bacterial membrane invaginated at the site of bactierial division

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16
Q

Plasmid DNA*

A

Self replicated unit of DNA distinct from chromosome

Much smaller than chromosome but can contain bacterial resistance genes*

*Give pathogenic attributes or antibiotic resistance to bacteria.. and are passed an as the bacteria divide and grow

Some are mobile* from one bacteria to another… also some can change species..

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17
Q

Flagella

A

Flagella

Used in bacteria for locomotion

Composed of flagellin

Different arrangements

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18
Q

What are different arrangements of flagella?

A

Monotrichous (vibrio cholerae)

Lophotrichous (bartonella bacilliformis)

Amphitrichous (spirillum serpens)

Peritrichous (escherichia coli)

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19
Q

Cell envelope

A

…

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20
Q

Bacterial Chromosome

A

Only one.. tightly packed

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21
Q

Where are bacterial resistance genes found? *

A

In the plasmid DNA

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22
Q

Ribosomes

A

No ER but do have ribosomes - protein synthesis and replication

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23
Q

Whatever is external on bacteria is highly antigenic

A

we make antiodies to kill bacteria

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24
Q

Flagellar Motor

A

The ability of some bacteria to move with prescence of flagella helps to figure out which antibiotic to use to treat…

Gram pos - 2 rings
Gram neg - 4 rings

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25
Q

Pili (fimbriae)

A

Shorter and finer than flagella..Two types:

adherence - allows bacterial to attach to places in body and cause diseases

ex - allows genetic info to be transmitted in some gram NEG bacteria

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26
Q

What is Fimbriae?

A

Another name for Pili

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27
Q

Cytoplasmic membrane

A

Encloses cytoplasm

Phospholipid bilayer -
selectively permeable
Embedded with proteins
Site of nutrient transport

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28
Q

Capsule

A

Slimy outer coating (not all bacteria) made of polysaccharides

GlycocalyxCan be antiphagocytic - hard for body to penetrate and kill

Pathogenic attribute of some bacteria.. biofilms

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29
Q

How does capsule relate to hip replacements?

A

Can cause biofilm on hip and cause infection..

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30
Q

Peptidoglycan

A

Unique component of bacteria60 - 90% by weight of gram POS bacterial cell wall, much less in gram neg*

another site of antibiotic action.. can inhibit the cell wall, thus make it hard for bacterial to regulate osmotic pressure

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31
Q

What is structure of peptidoglycan? how is it different in gram pos or gram neg?

A

Repeating units of NAM and NAG, some bacteria have tetrapeptide..

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32
Q

Peptidoglycan in a layer..

A

Cross-links between tetrapeptide chains. Helps keep structure*

Penicillian targets and inhibits the crosslinking, thus the bacteria isnt able to regulate osmotic pressure

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33
Q

What does penicillian do to bacteria?

A

It inhibits crosslinking between the tetra peptides in the peptidoglycan in certain bacteria, thus cell cannot regulate osmotic pressure..

34
Q

DIfferenece in gram pos and gram neg bacterial cell envelope?

A

Both have cytoplamic/bacterial membranes

Both have Peptidoglycan

Gram POS have much more peptidoglycan

35
Q

Why does more peptidoglycan on gram POS bacteria effect it?

36
Q

What is a gram stain?

A

Procedure to differentiate bacteria

37
Q

How does gram stain work?

A

Bacterial are heat fixed to a slide

Crystal violet is added (all turn blue)Iodine fixes the stain into cell (all turn purple)

Alcohol decolorizes gram NEG by removing outer membrane and removes dye

Safranin stains the gram NEG pink - just to show contrast..

38
Q

What are three components of bacterial structure only found in cell wall of gram POS?

A 
Teichoic acid
Lipoteichoic acid (LTA)
Polysaccharides
39
Q

So.. have a gram + bacterial invection of uri.. what is antibiotic to treat?

A

typical question

40
Q

What is teichoic acid?

A

Acid found only in gram POS bacterial cell wall - water soluable polymer of ribitol or glycerol residues linked by phosphodiester linkages

41
Q

What is teichuronic acid?

A

Lipoteichoic acid found only in gram POS bacterial inner plasma membrane - Similar to teichoic acid but made in phosphate limiting conditions

42
Q

What is LTA?

A

Lipoteichoic acid only found in gram POS bacterial inner membrane - lipid binded to teichoic acid - ADHESION

43
Q

What are polysaccharides?

A

Long carbohydrate molecules found only in gram POS bacteria - composites of sugars released from teichoic and teichuronic acids

45
Q

Talk about gram pos cell wall and gram neg envelope… why?

46
Q

What is endotoxin?

A

toxic component only associated with gram neg bacteria… body can react to endotoxin to cause endotoxic shock - deadly

Found in outermembrane of gram neg - found in lipopolysaccharides …

47
Q

Gram neg have outer membrane…

48
Q

antibiotics which inhibit crosslinking dont work very well in gram neg

49
Q

What is found only in gram neg bact?

50
Q

Periplasmic Space

51
Q

Lipoprotein

52
Q

Outer membrane

53
Q

Draw gram pos cell

54
Q

Draw gram neg cell

55
Q

Lipopolysaccharide (LPS)

A

made of? Lipid A portion of the LPS is the endotoxin.. it is attached toThe O-antigen is exposed to outside of cell..

56
Q

x

57
Q

What are mycoplasmas?

A

Smallest free-living organisms!

NO cell wall.. so.. no peptidoglycan and gram stains don’t work

Only barrier is cytoplasmic membrane, it contains sterols

Tough to treat with antibiotics and never really get rid of them..

58
Q

x

59
Q

s

60
Q

What are sterols?

A

Component of mycoplasma membrane - Required for growth of mycoplasmas but not synthesesized by the bacterium

61
Q

What do mycoplasmas look like?

A

Many of these pathogens exhibit filamentous or flask-shaped appearances

Have a prominent specialized polar tip for attaching to target cells

62
Q

s

63
Q

Distinguish between mycoplasmas and acid fast bacterias (mycobacteria)

A

Mycobacteria DO have small amounts of peptidoglycan and contain large amounts of glycolipids

64
Q

What are acid fast bacteria?

A

Mycobacteria and Nocardia

65
Q

What are features of glycolipids in mycobacterium?

A

LAM (lipoarabinomannan)
Mycolic acids (60% of cell wall)
Make cell walls impermeable

66
Q

s

67
Q

Acid fast stain

A

Will show if it is mycobacteria in lab

68
Q

What is acid fast staining?

A

It involves staining with red carbolfuchsin

Then destaining with acid alcohol…

*only acid fast bacteria will retain stain after decolorizing step

69
Q

What are mycolic acids?

A

Help make cell wall impermiable in mycobacteria.. 60% of cell wall

70
Q

What type of bacterium is tuberculosis?

71
Q

What do acid fast bacteria not have?

72
Q

Structure of secretion systems..

A

T1SS

Injectosome

73
Q

Injectosomes

A

Can inject things into other cells (mostly toxic substances)

Cause of many pathologies

Unique to individual strains of bacteria..

74
Q

Funciton of Protein secretion systems

A

Transport proteins or nucleic acids (T4SS) to outside of cell, periplasm, or inside host cells

Transport proteins can be surface proteins or toxins

75
Q

…

77
Q

s

78
Q

What is endospore formation?

A

Characteristic of SOME bacteria

Spore forms by enclosing nucleoid (along with dipicolinate) with a cortex, sporte coat, and spore wall

79
Q

…

80
Q

Cortex of endospore

A

Thickest part of the spore envelope

Contains peptidoglycan with fewer cross links

81
Q

Spore Coat of endospore

A

Contains keratin-like proteins, very impermeable to chemicals

82
Q

Spore wall (exosporium) of endospore

A

Contains normal peptidoglycan

Will become cell wall of germinating bacterium

Foundations of Medicine (42 decks)

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