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Biotechnology Flashcards

1
Q

What is biotechnology?

A

The industrial use of living organisms (or parts of living organisms) to produce food, drugs or other products

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2
Q

What are the main advantages of using microorganisms in biological processes?

A
  • No ethical issues when growing
  • Large variety of microorganisms
  • Genetically modified to produce protein required
  • Short life cycle & rapid growth rate - huge quantities can be produced in short periods of time
  • Cheap
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3
Q

What microorganism is involved in baking?

A
  • Yeast: mixed with sugar and water to respire aerobically
  • CO2 produced makes bread rise
  • Yeast cells are killed during cooking
  • Takes a couple hours
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4
Q

What microorganism is involved in brewing?

A
  • Yeast: respires anaerobically to produce ethanol
  • Mixed with malted barley and hot water
  • Fermentation continues for days in anaerobic conditions
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5
Q

What conditions are needed to make bread rise?

A
  • Oxygen
  • Heat
  • Carbohydrates (flour)
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6
Q

What microorganisms are involved in cheese making?

A
  • Bacteria: feed on lactose in milk, changing texture and taste, and inhibiting the growth of bacteria which makes the milk go off
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7
Q

What microorganisms are involved in yoghurt-making?

A
  • Bacteria: to form ethanol and lactic acid

- Both produce extracellular polymers that give yoghurt its smooth, thick texture

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8
Q

Why is milk pasteurised before being used commercially to make cheese and yoghurt?

A
  • To kill of most natural bacteria that would make it go bad rapidly
  • This is done by heating it for a certain amount of time.
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9
Q

Why is milk homogenised before being used commercially to make cheese and yoghurt?

A
  • To allow the fat droplets to evenly distribute through the milk
  • This will make the final product smoother and with less fat content
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10
Q

Give 2 differences between the production processes of cheese and yoghurt

A
  • The milk is heated in cheese making and cooled in yoghurt making
  • Whole milk is used in cheese making and skimmed milk is used in yoghurt making
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11
Q

Give 4 advantages of using microorganisms to produce human food?

A

1- Microorganisms reproduce fast and produce protein faster than animals and plants

2- They have high protein content with little fat

3- No welfare issues when growing microorganisms

4- Can be made to taste like anything

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12
Q

Give 4 disadvantages of using microorganisms to produce human food

A

1- Need sterile conditions that are carefully controlled which adds to cost

2- Protein has to be purified to ensure it contains no toxin or contaminants

3- Many dislike the thought of eating microorganisms grown on waste

4- Has little natural flavour - needs additives

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13
Q

Producing penicillin

A
  • Needs relatively high oxygen levels and a rich nutrient medium to grow well
  • It is sensitive to pH and temperature
  • A semi-continuous batch process is used
  • First stage = fungus grows
  • Second stage = produces penicillin
  • Drug is extracted from medium and purified
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14
Q

Key points about producing penicillin

A
  • Small fermenters (40-200dm3) as it’s difficult to maintain high levels of oxygenation in large ones
  • mixture is continuously stirred to keep it oxygenated
  • Rich nutrient medium
  • Growth medium contains a buffer to maintain pH at around 6.5
  • Bioreactors are maintained at about 25-27°C
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15
Q

What is bioremediation?

A

Where microorganisms are used to break down pollutants and contaminants in the soil or water

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16
Q

What are the different approaches to bioremediation?

A
  • Using natural organisms: many microorganisms naturally break down organic materials producing CO2 and water
  • GM organisms: scientists are trying to develop GM bacteria which can break down or accumulate contaminants which they would not naturally encounter
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17
Q

What are the requirements for optimal growth when culturing microorganisms in the lab?

A
  • Optimum temperature
  • Optimum pH
  • Oxygen (unless anaerobic)
  • Food (nutrient medium)
  • Aseptic technique conditions
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18
Q

How do you grow a broth culture?

A
  • Mix sterile nutrient medium with water to make broth
  • Mix known mass of dried bacterial culture with water to make suspension
  • Inoculate the sterile broth with a known volume of the bacterial suspension
  • Stopper the flask, with cotton wool or a bing with air inlet, to prevent contamination from the air
  • Incubate at suitable temperature, shaking regularly to aerate
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19
Q

How do you inoculate an agar plate?

A
  • The inoculating loop must be sterilised by holding it in a Bunsen flame until it glows red hot. It must not touch any surfaces as it cools to avoid contamination
  • Dip the sterilised loop in the bacterial suspension. Remove lid of Petri dish and spread liquid across surface
  • Replace the lid of the Petri dish. It should be held down with tape but not sealed comply so O2 can get in, or even the growth of anaerobic bacteria
  • Incubate at a suitable temperature
20
Q

What type of plates are there?

A
  • Spread (investigating antibiotics)
  • Pour (serial dilutions)
  • Streak (isolating a small number of bacteria)
21
Q

Aseptic techniques?

A
  • Heat loop to kill any microorganisms
  • Don’t put the lid down on the bench to avoid getting microorganisms on lid
  • The screw capped bottles are held at an angle so less SA is exposed to air = less contamination
  • Lid of Petri dish opened as little as possible = less air contamination
  • Mouth of second bottle is flamed = kill bacteria on neck
  • Used wire loop must be heated again = kill remaining bacteria
22
Q

What is the lag phase?

A

When bacteria are adapting to their new environment. They are growing, synthesising the enzymes they need and are not yet reproducing at max rate
- Rates are EQUAL

23
Q

What is the exponential phase?

A

Birth rate is GREATER than death rate

24
Q

What is the stationary phase?

A

Total growth rate is equal

Death rates are EQUAL to birth rates

25
Q

What is the death stage?

A

Death rate is GREATER than birth rate

26
Q

What are the limiting factors that prevent exponential growth in a culture?

A
  • Nutrients available: initially there’s plenty of food, but as numbers increase it’s used up and won’t support further growth
  • O2 levels: as population rises, so does the demand for O2
  • Temperature: enzyme-controlled reactions within microorganisms are affected by temperature of culture medium
  • Build-up of waste: as bacterial numbers rise, the build up of toxic material may inhibit further growth and can even poison/ kill the culture
  • Change in pH: as CO2 produced through respiration increases, the pH of the culture falls until a point where the low pH affects enzyme activity and inhibits population growth
27
Q

What are serial dilutions used for?

A

To dilute a bacterial culture, so that when you spread a sample onto an agar plate containing nutrients, only 30 to 300 bacteria will grow and produce colonies

28
Q

What are the two main ways of growing microorganisms?

A
  • Batch fermentation

- Continuous fermentation

29
Q

Outline the steps in batch fermentation

A
  • Microorganisms are inoculated into a fixed volume of medium
  • As growth takes place, nutrients are used up and both new biomass and waste products build up
  • As the culture reaches the stationary phase, overall growth ceases but during this phase the microorganisms often carry out biochemical changes to form the desired end products
  • The process is stopped before the death phase and the products are harvested. The whole system is then cleaned and sterilised and a new batch culture started up
30
Q

Outline the steps in continuous fermentation

A
  • Microorganisms are inoculated into sterile nutrient medium and they start to grow
  • Sterile nutrient medium is added continually to the culture once it reaches the exponential point of growth
  • Culture broth is continually removed - the medium, waste products, microorganisms and products - keeping the culture volume constant
31
Q

Why and how are bioreactors controlled?

A
  • Temperature: if too low they won’t grow quickly enough, if too high the enzymes start to denature and microorganisms are inhibited/destroyed
  • Nutrients and oxygen: O2/nutrient medium can be added in controlled amounts to the broth when probes or sample tests indicate that levels are low
  • Mixing things up: inside a bioreactor there are large volumes of liquid, which may be quite thick/viscous due to the growth of microorganisms. Simple diffusion is not enough to ensure all microorganisms receive enough food/oxygen. Most have a mixing mechanism and many are stirred continuously
  • Asepsis: if a bioprocess is contaminated by microorganisms from the air or workers, it can affect the yield. To solve this problem, most are sealed, aseptic units
32
Q

What are the advantages of using isolated enzymes?

A
  • Less wasteful: whole microorganisms use up substrate when growing, producing biomass rather than product
  • More efficient: work at higher concentrations
  • More specific: no unwanted enzymes present
  • Less downstream processing: cheaper
33
Q

Why are most of the isolated enzymes extracellular?

A
  • They are secreted so are easier to isolate and use
  • Each microorganism produces few extracellular enzymes, making it easy to identify and isolate the required enzymes
  • More robust than intracellular. Conditions outside a cell are less tightly controlled so can cope with greater variations of temp and pH
34
Q

What are immobilised enzymes?

A

Enzymes attached to an insoluble material

35
Q

What are the advantages of using immobilised enzymes?

A
  • Can be reused (cheaper)
  • Easily separated from reactants and products = reduced downstream processing (cheaper)
  • More reliable as there’s a high degree of control
  • Greater temp tolerance, less easily denatured
  • Ease of manipulation, catalytic properties altered to fit a particular process
36
Q

What are the disadvantages of using immobilised enzymes?

A
  • Reduced efficiency. The process of immobilising may reduce activity rate
  • Higher initial cost of materials. It’s more expensive than free enzymes or microorganisms
  • Higher initial costs of bioreactor. System is different from traditional fermenters
  • More technical issues. Reactors are more complex so more things can go wrong
37
Q

How are enzymes immobilised?

A
  • Absorption: surface immobilisation
  • Covalent bonding: surface immobilisation
  • Entrapment: in matrix
  • Encapsulation: membrane entrapment in micro capsules behind a semi permeable membrane
38
Q

What are the advantages and disadvantages of absorption surface immobilisation?

A

+ Simple and cheap to do
+ Can be used with many different processes
+ Enzymes very accessible to substrate and their activity is virtually unchanged

  • Enzymes can be lost from matrix relatively easily
39
Q

What are the advantages and disadvantages of covalent bonding immobilisation?

A

+ Cost varies
+ Enzymes strongly bound so unlikely to be lost
+ Enzymes very accessible to substrate
+ pH and substrate concentration often have little effect of enzyme activity

  • Cost varies
  • Active site of the enzyme may be modified in process, making it less effective
40
Q

What are the advantages and disadvantages of entrapment?

A

+ Widely applicable to different processes

  • May be expensive
  • Can be difficult to entrap
  • Diffusion of the substrate to and and product from the active site can be slow and hold up the reaction
  • Effect of entrapment on enzyme activity very variable, depending on matrix
41
Q

What are the advantages and disadvantages of encapsulation?

A

+ Relatively simple to do
+ Relatively small effect on enzyme activity
+ Widely applicable to different processes

  • Relatively expensive
  • Diffusion of the substrate to and product from the active site can be slow and hold up the reaction
42
Q

What are secondary metabolites?

A
  • Substances that are only produced by an organism in the stationary phase
  • E.g. antibiotics (penicillin)
43
Q

What are primary metabolites?

A
  • Substances produced as an essential part of the normal functioning of the organism
  • E.g. alcohol produced by yeast as a product of anaerobic respiration
44
Q

What is the hormone auxin used for?

A

Stimulate growth of root/root hairs

45
Q

What is the hormone cytokinins used for?

A

Stimulate me growth of shoot/stem

Biology (19 decks)

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