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Microbiology Exam 1 (Modules 1&2) > Chapter 3 > Flashcards

Chapter 3 Flashcards

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1
Q

Amphitrichous

A

Flagella at both poles of the cell.

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2
Q

Peritrichous arrangement

Hint: peri = around

A

Flagella are dispersed randomly over the surface of the cell

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3
Q

Lophotrichous

A

Small bunches, or tufts of flagella emerging from the same site

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4
Q

Monotrichous

A

Single flagellum

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5
Q

What is the primary function of the flagellum

A

Motility and propulsion

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6
Q

Chemotaxis

A

Movement of bacteria in response to chemical stimuli

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7
Q

Flagellum positive chemotaxis

A

Movement TOWARD favorable chemical stimulus

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8
Q

Flagellum negative chemotaxis

A

Movement away from a repellent

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9
Q

Run (flagellum)

A

Rotation of flagellum counterclockwise, resulting in a smooth LINEAR direction

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10
Q

Tumble (flagellum)

A

Reversal of the direction of the flagellum, causing the cell to stop and change course.

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11
Q

Attachment points of channels on the external surface of a bacterium

A

Fimbriae, pili, and nanotubes/nanowires

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12
Q

S layer

A

Single layers of thousands of copies of a single protein linked together like tiny chain link fences.

Only produced when bacteria are in a hostile environment.

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13
Q

Glycocalyx

A

Coating of repeating polysaccharide or glycoprotein units.

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14
Q

A glycocalyx is considered a __________ when the glycoprotein molecules are loosely associated with the cell wall.

A

slime layer

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15
Q

A glycocalyx is considered a _________ when glycoproteins are more tightly bound, denser, and thicker.

A

Capsule

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16
Q

Bacterium capsules

A

Formed by many pathogenic bacteria

Have greater disease-causing abilities (increased pathogenicity)

Protect against host white blood cells called phagocytes.

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17
Q

Biofilms

A

Plaque on teeth protects bacteria from becoming dislodged.

Responsible for persistent colonization of plastic catheters, IUDs, metal pacemakers, and other implanted medical devices.

Good location for bacteria to attach to and colonize.

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18
Q

How Archaea & Bacteria are different than Eukaryotes

A

How organisms are different from eukaryotes:

The way their DNA is packaged: lack of nucleus and histones.

The makeup of their cell wall: peptidoglycan and other unique chemicals.

Their internal structures: lack of membrane bound organelles

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19
Q

All bacterial cells possess:

A

Cytoplasmic membrane (holds cytoplasm inside)

Cytoplasm

Ribosomes

Cytoskeleton (structure)

One or a few chromosomes.

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20
Q

Most bacterial cells possess:

A
  • Cell wall

- Surface coating called glycocalyx

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21
Q

SOME but not all bacterial cells possess

A

Flagella, pili, and fimbriae (movement)

An outer membrane

Nanotubes

Plasmids

Inclusion bodies

Endospores

Microcompartments

*Most of these are observed in archaea as well

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22
Q

Many bacteria function as _________ and ________, unicellular organisms.

But some act as a _______ in colonies or biofilms.

Some communicate through _______.

A

; independent and single-celled
; group
; nanotubes

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23
Q

Bacteria have an average size of ____ _________.

A

; 1 micrometer

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24
Q

Cocci (plural): circumference of ________.

A

; 1 micrometer

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25
Q

Strepto-

A

=chain of

ie. Streptobacilli

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26
Q

Staphylo-

A

=irregular cluster of

ie. Staphylococcus

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27
Q

Rods: length of _______ and width of ________.

A

; 2 micrometers

; 1 micrometer

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28
Q

Pleomorphism

A

variations in cell wall structure caused by slight genetic or nutritional differences

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29
Q

Coccus

A

Ball or sphere shaped, can be perfectly round or oval/bean shaped, pointed variants; grape looking

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30
Q

Rod/Bacillus

A
  • varied in actual form
  • blocky, spindle shaped, round ended, long and thread like, drumstick shaped
  • when short and plump called “coccobacillus”
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31
Q

Vibrio

A

-gently curved rod shapes

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32
Q

Spirillum

A

Slightly curled or spiral shaped body; A rigid Helix, twisted twice or more along its axis.

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33
Q

Spirochete

A

resembles spring or corkscrew

flexible

34
Q

Filaments

A

Multiple branches off of a basic rod structure (ie. Streptomyces)

35
Q

Single coccus

A

one coccus

36
Q

Diplococci

A

two coccus

37
Q

Staphylococcus

A

irregular cluster of cocci

38
Q

Tetrads

A

groups of four

39
Q

Streptococci

A

chains of coccus

40
Q

Sarcina

A

cubicle packet of 8, 16, or more cells

41
Q

Diplobacilli

A

pair of cells

42
Q

Streptobacilli

A

chain of bacillus

43
Q

Palisades

A

cells of a chain that remain partially attached by a small hinger region at the ends

44
Q

Fimbria/Fimbriae

A

Small bristle-like fibers sprouting off the surface of many bacterial cells.

Allow tight adhesion between fimbria and epithelial cells, allowing bacteria to colonize and infect host tissues.

-can be for attachment or movement of fluid around cell

45
Q

Composition of cell envelope

A
  • Lies outside the cytoplasm
  • Composed of two or three basic layers that each perform a distinct function, but together act as a single protective layer
    1. Cell wall
    2. Cytoplasmic membrane
    3. Outer membrane (in some bacteria)
46
Q

bacteria that stain purple

A

gram-positive

47
Q

bacteria that stain red

A

gram-negative

48
Q

gram neg cell envelope

A

Gram neg cell envelope= closed sandwich with small middle peptidoglycan

49
Q

gram pos cell envelope

A

open sandwich with huge peptidoglycan

50
Q

The Cell Wall (in bacteria)

A

Provide strong structural support to keep the bacterium from bursting or collapsing because of changes in osmotic pressure:

  • Certain drugs target the cell wall, disrupting its integrity and causing cell lysis, which is disintegration or rupture of the cell.
  • Gains its relative rigidity from peptidoglycan.
51
Q

Peptidoglycan

A
  • Compound composed of a repeating framework of long glycan (sugar) chains crosslinked by short peptide (protein) fragments.
  • Provide a strong but flexible support framework
52
Q

Gram pos cell wall

A

Thick, homogeneous sheet of peptidoglycan:

20-80 nanometres in thickness.

Contains teichoic acid and lipoteichoic acid.

  • Function in cell wall maintenance and enlargement.
  • Contribute to the acidic charge on the cell surface.
53
Q

gram neg cell wall

A

Thin, single sheet of Peptidoglycan:
-much thinner than gram pos

1-3 nanometers in thickness (vs 20-80nm in gram pos)

Thinness gives gram neg cells more susceptibility to lysis (cell breakdown).

54
Q

Steps in Gram Staining

A
  1. Crystal violet stain (stains gram pos and neg purple)
  2. Gram’s iodine is added (stabilizer that causes dye to form complex mesh works in the peptidoglycan)
  3. Alcohol rinse (gram neg loses colour due to its thin layer of peptidoglycan and gram pos stays purple due to thick peptidoglycan trapping dye)
  4. Safranin (red dye) is then added causing the previously clear gram neg cell wall to turn red and the gram pos stays purple
55
Q

Non typical cell walls: acid-fast bacteria:

Mycobacterium and Norcardia

A

-Contain peptidoglycan and stain gram-positive (purple), but bulk of cell wall is composed of unique lipids.

Mycolic Acid (found in mycobacterium):

  • Very long chain fatty acid.
  • Found in the cell walls of acid-fast bacteria.
  • Contributes to the pathogenicity of the bacteria. Makes bacteria highly resistant to certain chemicals and dyes.
56
Q

Non typical cell walls: archaea

A

Exhibit unusual and chemically distinct cell walls.

Some have cell walls composed entirely of polysaccharides.

—» others have cell walls made of pure protein.

All LACK true peptidoglycan structure.

Some lack a cell wall entirely.

57
Q

Mycoplasms (genus of bacterium)

A

Naturally lack a cell wall

Sterols(fats) in the cell membrane stabilize the cell wall against lysis

Mycoplasma Pneumoniae: “walking pneumonia” (not as dramatic as bacterial pneumonia)

58
Q

L forms

A

Some bacteria that naturally have a cell wall but lose it during part of their life cycle

Role in persistent infections

Resistant to antibiotics

59
Q

The gram negative outer membrane

A

*Similar in composition to most membranes, except it contains specialized polysaccharides and proteins.

Lipopolysaccharides: lipids and then bunch of sugars

  • Signaling molecules and receptors
  • Endotoxin (harmful to human body - fever and shock)

Porin Proteins (think of pores in our face- membrane channels)

-Specialized membrane channels that only the outer membrane allows certain chemicals to penetrate

60
Q

Cytoplasmic Membrane Structure

A

A lipid bilayer with proteins embedded.
Serves as a site for:

Energy reactions

Nutrient processing

Synthesis

Regulates transport of nutrients and wastes —->

Selectively permeable: special carrier mechanisms for passage of most molecules

61
Q

Selectively Permeable Reasons of importance

A

Too much water out= cell shrinks and dies

Too much water in= cells bursts and dies

Too much sugar out= not enough food and dies

62
Q

Differences in Cell Envelope Structure *gram neg

A

Outer membrane of gram-negative bacteria has an extra barrier:

Resistant to certain antimicrobial chemicals

More difficult to inhibit or kill than gram positive bacteria (as neg has extra structure)

Alcohol based compounds dissolve lipids in the outer membrane and therefore damage the cell:

-Alcohol swabs used to cleanse the skin before certain medical procedures

**Treatment of infections caused by gram negative bacteria requires drugs that can cross the outer membrane.

63
Q

The Cytoplasm

A

70-80% water
sugars, amino acids, salts

Bacterial Chromosomes and Plasmids:
The hereditary material of most bacteria exists in the bacterial chromosomes
-DNA is aggregated in the nucleoid

Plasmids: nonessential pieces of DNA
-confer protective traits such as drug resistance and toxin/enzyme production

Ribosomes

  • site of protein synthesis
  • 60% rRNA and 40% protein

Inclusion Bodies/Microcompartments

  • food storage
  • pack gas into vesicles for buoyancy
  • store crystals of iron oxide

Cytoskeleton

  • some bacteria produce long polymers (protein) similar to eukaryotic cells for the cytoskeleton
  • in eukaryotic cells may be a potential target for antibiotic development
64
Q

Sporulation

A

induced by environmental conditions

65
Q

______ are the dormant type of cells that regrow into a new bacterium when the environmental conditions become favorable.
They are a result of _______.

A

; Endospores

; Sporulation

66
Q

Endospores

A

resist extremes of heat, drying, and freezing, radiation, and chemicals that would kill vegetative cells

-» really hard to kill and prevent infection

67
Q

Medical significance of Bacillus anthracis

A

agent of anthrax

68
Q

medical significance of Clostridium tetani

A

agent of tetanus

69
Q

medical significance of Clostridium perfringens

A

cause of gas gangrene

70
Q

Medical significance of Clostridium botulinium

A

cause of Botulism

71
Q

medical significance of Clostridium difficile

A

a serious gastro disease

72
Q

Archaea

A
  • a third cell type in a separate super kingdom
  • exhibit a novel method of DNA compaction
  • -> unique membrane lipids, cell wall components, and pilin proteins
73
Q

Archaea Extremophiles

A
  • some live at extreme high or low temps
  • some live on sulfur or methane
  • some need extremely high salt or acid concentrations to survive
  • Some live on the human body and may be capable of causing human disease
74
Q

Bacterial Species

A
  • A collection of bacterial cells, all of which have an overall similar pattern of traits
  • And share at least 95% of their genes as matches
75
Q

Subspecies, strain, or type:

A

-Bacteria of the same species that have differing characteristics

76
Q

Serotype

A

-Representatives of a species that stimulate a distinct pattern of antibody (serum) responses because of unique surface molecules

77
Q

Gracilicutes

A

taxonomic category of bacteria that have gram-neg envelopes; thin skinned

78
Q

Firmicutes

A

Taxonomic category of bacteria that have gram-pos cell envelopes; thick strong

Trick: A-firm-itive = gram pos

79
Q

Tenericutes

A

taxonomic category of bacteria that lack cell walls

80
Q

Mendosicutes

A

taxonomic category of bacteria that have unusual cell walls; archaea

Microbiology Exam 1 (Modules 1&2) (9 decks)

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