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Bio 1400 > Microbiology Chap 4 > Flashcards

Microbiology Chap 4 Flashcards

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Biology 101 flashcards
1
Q

Prokaryote characteristics

A

One circular chromosome not in membrane
No histones or membrane enclosed organelles
Peptidoglycan cell walls if Bacteria & pseudomurein cell walls if Archaea
Divide by binary fission

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2
Q

Eukaryote

A

Paired chromosomes, in nuclear membrane
Have histones & membrane enclosed organelles
Polysaccharide cell walls
Cell division by mitosis

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3
Q

Prokaryotes cell shape

A

Most bacteria are monomorphic (one shape); few are pleomorphic (many shapes)

  • Bacillus (rod-shaped)
  • Coccus (spherical)
  • Spiral
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4
Q

Cocci

A

Can be round, oval, elongated or flattened on one side
Can be found in
Pairs: diplococci
Chains: streptococci

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5
Q

Scientific name: Bacillus

Shape: Bacillus

A

Can be single, pairs (diplobacilli), chain (streptobacilli) or oval-like (coccobacillus)

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6
Q

Spirals

A
  • Have one or more twists & are never straight
  • Vibrio: curved rod
  • Spirillum: helical shape like corkscrew; have rigid bodies
  • Spirochete: helical shape & flexible bodies
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7
Q

Prokaryotes structures External to Cell Wall

A
  • Glycocalyx
  • flagella
  • axial filaments
  • fimbriae
  • pili
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8
Q

Glycocalyx

A

Sticky layer of polysaccharides outside of cell wall

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9
Q

Two types of Glycocalyx

A

Capsule: neatly organized and firmly attached

Slime layer: unorganized & loose

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10
Q

Capsules attribute to virulence by

A

Allowing cell to attach

Preventing phagocytosis

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11
Q

Atrichous

A

no flagella

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12
Q

Peritrichous

A

flagella all over the cell

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13
Q

Polar:

A

flagella on 1 side

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14
Q

Monotrichous:

A

1 flagellum

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15
Q

Amphitrichous

A

flagella on both sides

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16
Q

Lophotrichous

A

tuft of flagella coming from 1 side

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17
Q

Chemotaxis

A

chemical

18
Q

Phototaxis

A

light

19
Q

Flagella proteins

A

are H antigens distinguish among serovars

EXAM

20
Q

Axial Filaments

A
  • Also called endoflagella; found in spirochetes

- Bundles of fibrils that arise at end of cell beneath outer sheath, spiral around; anchored at one end of cell

21
Q

Axial filament rotation

A

Rotation causes cell to move like corkscrew

22
Q

protein pilin

A

is arranged in helical structure

23
Q

Fimbriae

A

: hairlike appendages that allow for attachment

24
Q

Pili

A
  • Involved in motitly & DNA transfer between cells
  • Gliding motility: smooth gliding movement
  • Twitching motility: pilus extends by addition of more pilin, makes contact & retracts as disassembled
  • Conjunction (sex) pilus: F+ cells connects to receptors on another cell & DNA from F+ cell is transferred
25
Q

Cell Wall

A

Prevents lysis when water pressure inside cell is greater then outside
Helps maintain shape, anchor flagella & contributes to virulence

26
Q

Gram-positive Cell Walls

A
  • Thick peptidoglycan
  • Teichoic acids (2 types)
  • Lipoteichoic acid links to plasma membrane
  • Wall teichoic acid links to peptidoglycan
  • May regulate movement of cations & attribute to antigen specificity
  • Polysaccharides & teichoic acids provide antigenic specificity
27
Q

Gram-Negative Cell Wall

A
  • Thin peptidoglycan (bonded to lipoproteins) & outer membrane
  • Periplasmic space filled with periplasm (gel-like fluid); high concentration of degradative enzymes & transport proteins
  • More prone to mechanical breakage; sensitive to tetracycline
28
Q

Gram-Negative Cell Wall stuff

A

Outer membrane: consists of lipopolysaccharides (LPS), lipoproteins & phospholipids; protection from phagocytes, complement (lysing cells & phagocytosis) & antibiotics

29
Q

LPS consists of

A

O polysaccharide antigen: useful in identifying gram-negative, ex. E. coli O157:H7
Core polysaccharide: provides stability
Lipid A is endotoxin; causes fever, dilation of blood vessels, shock & blood clotting

30
Q

Gram-stain

A

Crystal violet-iodine crystals form in cell, which are too large to leave

31
Q

Gram-positive (alcohol)

A

Alcohol dehydrates peptidoglycan making it more impermeable & CV-I crystals do not leave

32
Q

Gram-negative (alcohol)

A

Alcohol dissolves outer membrane & leaves holes in peptidoglycan letting CV-I wash out

33
Q

Safranin dyes

A

both pink but only visible in Gram-negative

34
Q

Gram-positive cell walls

A
  • 2-rings in basal body of flagella
  • Produce exotoxins
  • High susceptibility to penicillin
  • Disrupted by lysozyme
35
Q

Gram-negative cell walls

A
  • 4-rings in basal body of flagella
  • Produce endotoxins & exotoxins
  • Low susceptibility to penicillin
36
Q

Acid-fast cell walls

A 
Like gram-positive
Waxy lipid (mycolic acid) bound to peptidoglycan
37
Q

Mycoplasmas

A
  • Lack cell walls

- Sterols in plasma membrane

38
Q

Archaea

A

Wall-less or walls of pseudomurein (lack NAM & D-amino acids)

39
Q

Cell envelope layers

A

Outer membrane
Cell wall
Plasma membrane

40
Q

Cell envelope

A 
-Gram-negative
All 3
-Gram-positive
-Missing the outer membrane
-Mycoplasma
Only have the plasma membrane
41
Q

Damage to Cell Wall

A
  • Lysozyme digests disaccharide in peptidoglycan
  • Found in sweat, tears & saliva
  • Penicillin inhibits peptide bridges in peptidoglycan
  • Protoplast is wall-less cell
  • Spheroplast is wall-less gram-positive cell
  • Protoplasts & spheroplasts are susceptible to osmotic lysis
  • L forms are wall-less cells that swell into irregular shapes

Bio 1400 (13 decks)

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