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microbiology > ch. 3 - prokaryotic profiles: bacteria + archaea > Flashcards

ch. 3 - prokaryotic profiles: bacteria + archaea Flashcards

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Biology 101 flashcards
1
Q

what differentiates prokaryotes (simplest creatures) from eukaryotes?

A
  • the way their DNA is packaged (lack of nucleus + histones)
  • the makeup of their cell wall (peptidoglycan + other chemical)
  • their internal structure ( lack of membrane-bounded organelles
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2
Q

what do ALL bacterial cells possess?

A
  • cell membrane
  • cytoplasm
  • ribosomes
  • a cytoskeleton
  • one (or a few) chromosomes
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3
Q

what do MOST bacterial cells possess?

A
  • a cell wall
  • a surface coating called a glycocalyx
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4
Q

what structures are only shown in SOME bacteria?

A
  • fimbriae, pili, + flagella
  • outer membrane
  • plasmids
  • inclusions/granules
  • capsule
  • endospores + intracellular membranes
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5
Q

what is pleomorphism?

A
  • when the cells of one species may vary in shape + size

—– caused by variations in cell wall structure

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6
Q

what are the bacterial shapes?

A

coccus –> spherical or ball-shaped

bacillus –> rods

vibrio –> curved rods

spirillum –> helix shape with 2-3 bends (corkscrew shaped)

spirochete –> 3 or more bends (spring shaped)

branching filaments –> multiple branches off of a rod shape

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7
Q

what are flagella? (prokaryotic propellers)

A
  • for bacterial locomotion
  • three distinct parts
  • comprised of many proteins
  • 360 degree rotation
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8
Q

flagellar arrangement: what is monotrichous?

A

single flagella (1)

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9
Q

flagellar arrangement: what is lophotrichous?

A

small bunches of tufts of flagella (same site)

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10
Q

flagellar arrangement: what is amphitrichous?

A

flagella at both poles of the cell

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11
Q

flagellar arrangement: what is peritrichous?

A

flagella dispersed randomly over the surface of the cell

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12
Q

why do bacteria move and to where?

A
  • avoid danger/hide
  • look for nutrients
  • get a host (spread)
  • exchange DNA
  • reach stimulus
  • good environment to reproduce/ different place to live
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13
Q

what two ways can flagella move?

A
  • runs: smooth lineal movement toward a stimulus
  • tumbles: flagellar rotation reverses, causing the cell to stop + change its course
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14
Q

what is chemotaxis?

A
  • bacteria move in response to chemical signals
  • receptors bind extracellular molecules, which triggers flagellum to rotate
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15
Q

what are endoflagella?

A
  • flagella is within the cell outer membrane
  • spirochetes
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16
Q

what are fimbriae?

A
  • used for attachment, especially to endothelial cells
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17
Q

what are pili?

A
  • used for attachment + genetic exchange during conjugation
18
Q

what is conjugation?

A
  • exchanging of genetic material
19
Q

do bacteria have cillia?

A

no

20
Q

what is the glycocalyx?

A
  • sugar covering composed of polysaccharides, proteins or both
  • for attachment (sticky –> sticks to surfaces) + protection

used to avoid phagocytosis + for adhesion (biofilms)

thickness varies:
slime layer - thin
capsule - medium
biofilm - thickest

21
Q

what is a capsule?

A
  • a type of glycocalyx covering –> bound more tightly to cell + denser and thicker
  • produces a sticky (mucoid) character to colonies (cells stick together
  • encapsulated bacteria = have greater pathogenicity
22
Q

what is a cell envelope?

A
  • lies outside of the cytoplasm
  • composed of two or three basic layers:
    1) cell wall
    2) cell membrane
    3) outer membrane on some bacteria
23
Q

what is the cell wall?

A
  • helps determine shape of bacterium (in most)
  • strong structural support = keep bacterium from bursting or collapsing bc of changes in osmotic pressure
  • certain drugs target the cell wall = causing cell lysis (disintegration or rupture) of the cell
  • gains rigidity from peptidoglycan
24
Q

how is the peptidoglycan cell wall structured?

A
  • long glycan (sugar) chains cross-linked by short peptide (protein) fragments
25
Q

structures of gram positive cell?

A
  • thick peptidoglycan
  • teichoic acid + lipoteichoic acid
  • one membrane
  • slow, multi-celled
26
Q

structures of gram negative cell?

A
  • thin peptidoglycan
  • lipopolysaccharide (lipid A stimulates fever + shock) = most potent endotoxin in nature
  • two membranes (outer membrane + cell membrane)
  • porin proteins
  • fast, single-celled
27
Q

do archaea have peptidoglycan in their cell wall?

A

no, only prokaryotes

28
Q

what is acid-fast bacteria?

A
  • mycobacterium sp. and nocardia sp.
  • contains mycolic acid (a wax)
  • modified gram-positive structure

must use when trying to ID important pathogens causing:
- tuberculosis

  • leprosy
29
Q

what is cell wall deficient bacteria?

A
  • cell membrane stabilized by sterols is resistant to lysis

ex.) mycoplasma pneumoniae

30
Q

what is the cytoplasmic membrane?

A
  • lets things in and out aka nutrients
  • lipid bilayer (phospholipids) with proteins embedded
  • site for reactions = contains enzymes of respiration + ATP synthesis bc lacking of mitochondria in prokaryotes
31
Q

what is the cytoplasm?

A
  • 70-80% water
  • soluble proteins, salts, carbohydrates
  • site of nearly all chemical reactions
  • contains DNA in the nuceloid
32
Q

what is bacterial DNA?

A
  • bacteria DNA mostly exists in the form of a single circular bacterial chromosome
  • is aggregated in a dense area of cell = called nucleoid
33
Q

what is a plasmid?

A
  • nonessential pieces of DNA
34
Q

where is the nucleoid?

A

in a central subcompartment in the cytoplasm

35
Q

what is the prokaryotic ribosome?

A

total size = 70s

subunits: large subunit - 50s
small subunit - 30s

  • translates mRNA into proteins
  • 60% rRNA + 40% protein
36
Q

what are inclusions/granules?

A
  • non-membrane bound granules
  • usually for storage of nutrients
37
Q

what is the cytoskeleton?

A
  • peptidoglycan layer = determines shape
  • others use protein fibers - actin + tubulin - to alter cell shape
38
Q

what are bacterial endospores?

A
  • for survival
  • resist extremes of heat, drying, freezing, radiation, + chemicals that would kill vegetative cells
  • produced by species in genus = bacillus, clostridia, + sporosarcina
39
Q

how are endospores formed:

A

1)

2)

3)

40
Q

what are archaea?

A
  • prokaryotic microorganisms
  • many are found in extreme environments
  • different from members of the domains bacteria and eukarya in terms of: cell structure, metabolism, + genetics

microbiology (7 decks)

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