microbial growth Flashcards

1
Q

name the essential nutrients from microorganisms

A

C,H,O,N,S,Se,P

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2
Q

out of the essential nutrients which ones have simple metabolism

A

P,N,S

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3
Q

sources of C

A

CO2, org compounds

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4
Q

sources of N

A

NH3,NO3,N2, organic N compounds (AA,etc)

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5
Q

sources of H

A

H2O, organic compounds

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6
Q

sources of O

A

H2O,O2, org compounds

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7
Q

sources of P

A

PO4 (3-)

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8
Q

sources of S

A

H2S, SO4 (2-) ,org S compounds (cysteine), metal sulfide (FeS,CuS,ZnS, etc)

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9
Q

sources of K

A

K+ in solution, K+ salts

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10
Q

sources of Mg

A

Mg in solution, Mg salts

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11
Q

sources of Ca

A

in solution, salts

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12
Q

sources of Na

A

in solution, salts

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13
Q

Sources of Fe

A

Fe2+ , Fe3+

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14
Q

what are growth factors

A

vitamins, AA, purines, pyrimidines or other ORGANIC MOLECULES.
- needed for growth and NOT synthesized by the organism

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15
Q

some growth factors are the. —– or —- of another micro-organism

A

by products, waste

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16
Q

growth of the population = increase —- or —-

A

number of cells, biomass

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17
Q

what is a septum

A

the partition created that constricts the cell into 2 daughter cells

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18
Q

explain the process of septum formation

A

cell elongation –> septum formation –> completion of septum –> formation of walls –> cell separation

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19
Q

each daughter cell receives one copy of the —-, sufficient —, —- and etc

A

chromosome, ribosome, macromolecules

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20
Q

cell division requires —- and cell wall —– by —-

A

cell wall synthesis, destruction, autolysins

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21
Q

destroying and making — is the ket to cell division

A

peptidoglycan

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22
Q
  • —- allows peptidoglycan to be exported across the cytoplasmic membrane.
  • location?
A

bactoprenol, where the septum is being made.

- adds new peptidoglycan to initiate separation

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23
Q

at the division ring (FtsZ), —- create some — in the peptidoglycan. this allows:

A

autolysins, gaps, rearrangement of the peptidoglycan and synthesis of a new cell wall

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24
Q

wall bands

A

scar between old and new peptidoglycan

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25
Q

why do different bacterial cultures smell different

A

they have different metabolic pathways; produces different wastes.
- also depends on the characteristics of the species and the media

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26
Q

name different selective mediums mentioned in the class

A

1) bile salts

2) mannitol salt

27
Q

bile salts —- gram + , —– for gram - and enteric pathogens

A

inhibit, permissive

28
Q

bile salts is toxic for a lot of microorganisms but not for —–

A

enteric pathogens. like the ones in the intestine

29
Q

lactose fermenters have a — color. lactose non fermenters are — . this color change is indicated by a —

A

pink, colourless, pH indicator

30
Q

mannitol salt has a high —- concentration. —– most gram negative and many gram positive

A

NaCl, inhibits

31
Q

mannitol salt is used for isolation and detection of —-. how does this work?

A

staphylococcus, some are mannitol negative (cannot ferment mannitol) and turn the media pink, but some are mannitol positive and produce acids that turn the media yellow

32
Q

staphylococcus, mannitol + –>

staphylococcus, mannitol negative —>

A

staphylococcus aureus

staphylococcus epidermis

33
Q

function of staphylococcus aureus

A

wound infection, has a high antibiotic resistance

34
Q

what is a viable count

A
  • measured to test microbial presence
  • needs a permissive growth medium
  • results are reliable when there are between 30 - 300 colonies
35
Q

name the methods of viable count

A

1) spread plate method

2) pour plate method

36
Q

to get a viable count of culture with ing populations, —- are done

A

serial dilutions

37
Q

serial dilution counts ——-

A

the number of cells that are able to grow

- dead cells cannot be counted

38
Q

with —– you can also count dead cells

A

microscopic method ** know how to calculate them

39
Q

—– an be used to differential between living and non living cells

A

viability staining

40
Q

advantages and disadvantages of microscopic method

A

adv: fast non need to wait until the bacteria has grown
disadvantages: small cells can be missed, motile cells are hard to count

41
Q

flow cytometry is better at counting — cells. like:

A

big, protozoan, yeast, mammalian cells, etc

42
Q

how does flow cytometry work

A

1) aligns all cells behind each other
2) the cells go through a detection device which is a laser
3) they pass the laser
4) the light transmitted is detected by a machine
- specifies which ones are dead or alive if you use the culture of microscopic counts that are already stained

43
Q

turbidimetric method

A

measures the contribution of alive and dad cells to turbidity
- high optical density = high turbidity

44
Q

turbidimetric method is affected by:

A

1) clumping: form large particles –> error –> higher OD

2) attachment to surfaces –> lower OD

45
Q

how is the turbidimetric method done

A

measured using a spectrometer, by measuring the amount of light that goes through
- technically measures the OD: log I0/I

46
Q

The relationship between the number of cells and OD depends on:

A

the type of the cell: size, shape, composition, cells inclusion, mutations, etc

47
Q

generation time

A

the time needed for the population to double

- depends on the growth medium and conditions

48
Q

when the conditions are right, microorganisms can grow —–

A

exponentially , the population forms at a constant rate
equation
N = N02^n –> number of cells

49
Q

calculating generation time

A

g = t/n

50
Q

know the growth cycle

A

in the notes

51
Q

most natural envs are —–, they have:

A

open systems

1) constant supply of nutrients and diffusion of waste
2) predations
3) competition with other microorganisms
4) changing env conditions

52
Q

chemostats

A

notes

53
Q

factors affecting growth

A

1) temp
2) pH
3) osmolarity
4) oxygen
5) pressure
6) radiation

54
Q

extremophiles

A

microorganism that grow preferentially under extreme conditions

55
Q

membrane gelling

A

transport processes so low that growth cannot occur

56
Q

what happens above the optimum growth rate

A

thermolysis

57
Q

membrane gelling occurs at:

A

minimum temp *doesn’t kill them

58
Q

the temp range for most microorganism is typically —-

A

25- 40 degrees around the optimal temp

59
Q

psychrotolerant

A

can grow at zero degrees but have a optimal range of 25-40 degrees

60
Q

psychrophile

A

notes

61
Q

mesophile

A

notes

62
Q

thermophile

A

notes

63
Q

hyperthermophile

A

notes

64
Q

barophilic

A

grow best at high pressure