technique de labo Flashcards

1
Q

Spread-plate method

A
  • pipette
  • spread the sample evenly over surface of agar
  • Incubation
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2
Q

Pour-plate method

A
  • Sample pipette into sterile plate
  • Sterile medium added and mixed
  • Solidification and incubation
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3
Q

What do u need for growth to happen?

A

permissive growth medium

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4
Q

When are results reliable ?

A

colonie btw 30-300

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5
Q

Serial dilution, bacterial culture can reach?

A

high humbers of cells

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6
Q

serial dilution, How to get viable count of such cultures?

A

serial dilutions have to be made

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7
Q

Seria dilution, the resulsts and reproducibility are strongly affected by?

A

the skills of the technician

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8
Q

CFU

A

number of colonie / dilution x volume plated

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9
Q

microscopic counts

A

use of special slides known as counting chambers

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10
Q

microscopic counts, tu dois faire attention a pas

A

overflow

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11
Q

microscopic counts, technique where u can?

A

count cells, dead , alive, and the one’s who can’t grow in lab

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12
Q

What can be used to differentiate dead from alive?

A

Variability staining

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13
Q

microscopic counts, what are the pros?

A
  • Fast

- No need to wait until bacteria has grown (no incubation)

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14
Q

microscopic counts, cons?

A
  • Small cells can be missed

- motile cells are hard to count and must be immobilized

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15
Q

What happen if a cell is on the line?

A

u count it but u don’t count the ones who are at the top or at the bottom

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16
Q

Flow cymetry

A

technology that is used to analyse the physical and chemical characteristics of particles in a fluid as it passes through at least one laser.

17
Q

flow cymetry, is better at?

A

counting big cells

18
Q

Big cells like ?

A

Protozoan,yeast,mammalian,cells

19
Q

flow cymetry, what allows labeling of specific cell types or species

A

Detection of fluorescent dyes

20
Q

Flow cymetry, en gros?

A

a chaque fois que passe une cellule le laser est interrompu et un signal est donner

21
Q

flow cymetry, et quand une cellule par exemple stained passe?

A

le laser emet deux type de reflection , une reflextion stained et une reflexion normale

22
Q

flow cymetry can be used to sort cells according?

A

size,shape,labeling

23
Q

cons of Flow cytometry?

A

can be time consuming and expensive

24
Q

Turbidimetric method

A

the process of measuring the loss of intensity of transmitted light due to the scattering effect of particles suspended in i

25
turbidity is measured with?
spectrophotometer
26
spectrophotomer?
an instrument that passes light through a cell suspension and measures the unscattered light that emerges
27
A spectrophotometer employs a?
prism or diffraction grating to generate incident light of a specific wavelength (
28
what happens in the spectrophotometer en ordre?
- Light - Prism ( generate incident light ) - passes filter - runs through the sample containing cells - Photocell (measures unscattered light)
29
what is measured is?
the optical density ( log Io/I)
30
turbidity works until &
jusqu'a une certaine concentration
31
specto, measures both contribution of ?
both living and dead cells
32
OD is affected by?
properties of cells: size, clumping
33
If bacterias form aggregates?
can decrease the spectograph measurement
34
spectogram is viable btw ?
90.1 and 1
35
A standard curve must be made and the relationship between OD and cell number must be established?
empirically