unit 6 Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

what are the resources microorganisms need to grow

A
  • nutrients
  • oxygen ( anaerobic organisms require the absence of oxygen)
  • optimum pH
  • favorable temperature
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

why do microorganisms should be cultured with great careand what are the safety precautions

A
  • there is a risk that a mutation leads to the formation of a pathogenic strain which could contaminate the bacterial culture
  • follow healthy and safety precaution
    . ensure that all equipment are sterilized before culturing bacteria
    . keep culture in the laboratory
    . seal the cultures in a plastic bag and sterilize at a higher temperature and pressure
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

why do microorganisms should be cultured with great careand what are the safety precautions

A
  • there is a risk that a mutation leads to the formation of a pathogenic strain which could contaminate the bacterial culture
  • follow healthy and safety precaution
    . ensure that all equipment are sterilized before culturing bacteria
    . keep culture in the laboratory
    . seal the cultures in a plastic bag and sterilize at a higher temperature and pressure
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what are the steps of culturing

A
  • obtain a supply of the type of microorganism
  • ensure that the nutrient medium is kept under sterilize conditions
  • by adjusting the medium nutrient conditions will be created for the optimal growth of a microorganism this called selective medium
  • microorganisms are introduced to a growth medium using inoculation with a sterilised inoculation loop (can be used to transfer microorganisms)
  • incubate at around 20 C
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what are the methods of measuring the growth of microorganisms

A
  • cell counts
  • dilution plating
  • measuring area and mass
  • optical methods
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what are the steps of culturing

A
  • obtain a supply of the type of microorganism
  • ensure that the nutrient medium is kept under sterilize conditions
  • by adjusting the medium nutrient conditions will be created for the optimal growth of a microorganism this called selective medium
  • microorganisms are introduced to a growth medium using inoculation with a sterilised inoculation loop (can be used to transfer microorganisms)
  • incubate at around 20 C
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

when is it possible to use sampling and what is it used for

A

for larger and complex habitat where it is not possible to identify and its used for investigating the abundance and distribution of a specie or a population

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

how to measure the growth of microorganisms using cell counts

A
  • microscope and haemocytometer are used to count single-celled microorganisms
  • a nutrient broth is diluted with an equal volume of trypan blue which stains dead cells and allows to count only living organisms
  • the number of living organisms in four corner square are counted
  • the haemocytometer is callibrated to allow the calculations to the number of cells in a known volume of broth
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

how to measure the growth of microorganisms using optical methods

A

by Turbidimetry which is measuring the intensity of light that passed through the sample
- the greater the number of cells the more turbid the solution is
- this provides an indirect measure of microorganisms
- a calibration curve can be constructed by measuring the turbidity of a series of
control cultures while also using haemocytometer; the results are plotted in a graph of turbidity against cell count

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