Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

microbio > week 10 > Flashcards

week 10 Flashcards

(73 cards)

Start Studying
1
Q

what is a biofilm

A

community of microbial cells that are attached to a surface by an extracellular polymeric matrix (EPM)

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

true or false: about 95% microorganisms live in biofilms as long as there is at least a minimal amount of water and nutrients

A

true

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

the architecture of a biofilm supports the transport of…….

A

nutrients

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

biofilms:
provide habitat………
facilitate resource…..
promote community……..
protect cells from……..

A

diversity
capture
interconnectivity
environmental hazards

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

why are cells in biofilm 100-1000x more resistant to antibiotics

A

-physical barrier
-charged matrix
-horizontal gene transfer
- degradation of antibiotics
-persister cells
- diversity

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

what kinds of surfaces can biofilms form on

A

living tissues, indwelling medical devices, natural/ industrial systems, etc.

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

the NIH estimates that what percent of infections are caused by microorganisms growing in a biofilm?

A

80%

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

bacteria growing in biofilms help remove…….from wastewater

A

dissolved organics (unwanted)

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

how does growing attached to a surface improve fitness

A

close to other bacteria/ communities to communicate/ share resources

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

why can biofilms cause industrial systems to fail?

A

can cause localized corrosion in fuel storage tanks

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

quorum sensing identifies…….

A

population density

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

sequence of formation of biofilm

A
  1. organic/inorganic molecules + ions pre-condition the surface
  2. planktonic cells reversibly adhere to surface
    -initial attachment by adhesins surface proteins
    -hydrophobic/ hydrophilic + Van der Waals interactions
    -contact through pili/fimbriae
  3. nutrients available = cells irreversibly attach to surface
    -adhesive EPM
  4. cells begin to replicate + produce EPM
    -quorum sensing triggers binding to form microcolonies
  5. 2ndary colonizers partition the biofilm into niches/ water channels
  6. external parts of the biofilm may detach
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

dispersal is triggered by 3 major factors

A
  • starvation: depletion of C or N, intracellular starvation signals

-density: quorum sensing mediated release

-toxins: reactive oxygen species, particularly NO

mechanical stress can also cause biofilms to disperse

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

3 distinct varieties in which biofilm dispersal occurs

A
  • erosion: release of single cells or small clusters of cells at low levels
  • sloughing: sudden detachment of large portions of the biofilm
  • seeding: rapid release of a large number of cells following the formation of hollow, fluid-filled cavities inside biofilm
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

many bacteria produce hollow biofilms, filled with……and…..

A

fluids
planktonic cells

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

two main strategies for managing problematic biofilm formation

A
  1. inhibition
  2. dispersal
    -physical
    -chemical
    -enzymatic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

3 main variables important to cell attachment, biofilm formation development

A
  1. adhesion surface
    -texture
    -charge
    -hydrophobocity
  2. bulk fluid
    -flow velocity
    -pH
    -temp
    -nutrient
  3. cell
    -appendages
    -EPM
    -signaling molecules
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

3 methods to get rid of biofilms

A

physical removal

chemicals to dissolve

enzymes to disperse

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

Shelford’s law of tolerance

A

max. and min. limits of an organism control their abundance and distribution

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

5 environmental stressors that bacteria

A
  1. pH
  2. temp
  3. osmolarity
  4. oxygen
  5. starvation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

-log(Ka) =

A

pKa

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

when pH = pKa…..

A

concentration of dissociated and undissociated acids will be equal

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

when pH > pKA….

A

more molecules will dissociate

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

when pH < pKA….

A

fewer molecules will dissociate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
all C-termini and N-termini can.....
donate/ accept protons
26
at pH > pKa.... amino acids will.....
donate protons
27
If the pH strays too far from optimum, the presence of H+ or OH– ions will disrupt........
bonds in the tertiary structure
28
how can pH affect the properties of an R-group
electrostatic attraction between molecules of solution + R groups = decreased enzyme affinity
29
bacteria prevent denaturation or lowered enzyme affinity by.....
maintaining a consistent internal pH
30
neutrophile pH
internal 7.5-8 external 6-8
31
acidophile pH
internal 6.5-7 external 1-4
32
alkaliphile pH
internal 8.4-9 external 9-12
33
true or false: acids can diffuse very quickly through the membrane bc of the negative charge
FALSE acids diffuse slowly c of the positive charge
34
at low pH, concentration of H+ ions.......the pressure
increases
35
To adapt to internal pH changes, bacteria must be able to do two different things:
alkalize cytoplasm acidify cytoplasm
36
4 ways to alkalize cytoplasm:
1. proton pumping 2. potassium pumping 3. reduce membrane permeability 4. produce ammonia
37
2 ways to acidify cytoplasm:
1. Na+/ H+ anti-porting 2. K+/ H+ anti-porting
38
if cytoplasm is too acidic, then....
more protons are pumped out than in
39
...........limits the amount of H+ that can be moved to outside the cell
accumulation of + charges outside the cell
40
to balance the internal charge when protons are pumped outwards, cells......
pump K+ ions back inside the cell
41
saturated fatty acids are more hydro...... than unsaturated
hydrophobic
42
saturated fatty acids are.......permeable to H+ ions
less
43
bacteria can increase the pH with enzymatic......
activity
44
example of enzymatic activity to increase pH
producing ammonia from urea with urease
45
deaminase can increase pH by.......
removing the amine group from an amino acid or nucleotide
46
alkaliphiles acidify the cytoplasm by.......
supplementing normal H+ pumping with Na+/ H+ anti-porters
47
high temps cause proteins to......and membranes to become more.......
denature permeable
48
low temps......membrane permeability and......chemical reaction rates
reduce reduce
49
at higher temps, bacteria modify membrane fatty acids to contain.....saturated fatty acids
more
50
saturated fatty acids have......melting points
higher
51
many bacteria produce.........to restore protein function after high temps
heat shock proteins (Hsps)
52
newly synthesized proteins need the help of....... to fold into
chaperone proteins
53
Hsp70
heat-shock chaperone protein that helps fold proteins using energy from ATP
54
Hsp70 is activated by binding ATP, which.......
opens the active site to the unfolded polypeptide
55
Hsp40
binds unfolded polypeptides and delivers them to Hsp70
56
Hsp70 closes around the unfolded protein and provides energy from......and a suitable environment for protein folding
ATP hydrolysis
57
a.......replaces ADP with ATP , which triggers Hsp70 to release the newly folded protein
nucleotide exchange factor
58
in addition to folding new proteins, Hsp70 can.....
help refold denatured proteins
59
unfolded proteins can form......usually due to exposed hydrophobic domains
aggregates
60
some Hsps, like....... are able to disentangle aggregates before feeding polypeptides to Hsp70 and Hsp40
ClpB
61
if misfolded proteins cannot be refolded, then......
they are degraded to prevent the toxic accumulation of aggregates
62
there are at least......ATP-dependent proteases Hsp's
6
63
most bacteria live in ......tonic solutions
hypo
64
turgor pressure
pressure exerted on the cell wall from water expanding inside the cell
65
isotonic solution
no net movement of water cell membrane attached to cell wall
66
hypertonic solution
water particles move out of the cell cell membrane shrinks and detaches from cell wall shrunken cell
67
hypotonic solution
water particles move into the cell cell wall counteracts osmotic pressure swelling + lysis
68
4 mechanisms bacteria use to respond to changes in osmolarity
1. salting out 2. accumulation of compatible solutes 3. expression of aquaporins 4. opening/ closing of mechanosensitive channels
69
when turgor pressure is too high, bacteria can "salt-out" by......
trasnsporting Na+ out of the cell
70
when turgor pressure is too low, bacteria.....
accumulate compatible solutes
71
compatible solutes include
any non-toxic osmolytes in cytoplasm can be organic or inorganic
72
after increasing intracellular K+, cells.......
switch to other organic compatible solutes sugars, poly-acids, amino acids
73
osmolarity formula
osmolarity = moles ions/ L solution

microbio (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions