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Biology Paper 2 > Cloning & Biotechnology > Flashcards

Cloning & Biotechnology Flashcards

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1
Q

Define clone

A
  • Genetically identical organisms
  • Derived from a single original parent cell
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2
Q

Define cloning

A

Production of an organism genetically identical to another organism

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3
Q

Outline natural methods of cloning in some eukaryotes

A
  • Asexual reproduction in plants (e.g. tubers)
  • Budding in fungi
  • Identical twins are clones - originate from the same cell
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4
Q

Define asexual reproduction

A
  • One parent needed
  • Offspring are genetically identical to each other and the parent
  • Product of mitosis
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5
Q

Give examples of asexual reproduction in plants

A

Strawberry runners
- New plant develops at end of lateral stem

Potato tubers
- Buds on storage organ develop to produce new shoots

Bulbs (e.g. daffodils)
- Buds form internally
- Develop into new shoots and plants in next growing season

Rhizomes (e.g. marram grass)
- Horizontal stem that grows underground
- Buds develop to from new vertical shoots

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6
Q

Describe the process of taking a cutting

A
  • Use a scalpel to take a small piece of plant
  • Dip in rooting powder
  • Replant in soil
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7
Q

Why are plant cuttings often used in horticulture?

A
  • Faster than planting seeds
  • Guarantees quality of plants
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8
Q

What is the disadvantage of using plant cuttings rather than seeds?

A

Reduced genetic variation in population

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9
Q

Describe an experiment to investigate the factors which affect rooting in stem cuttings

A

Possible independent variables:
- How many leaves are left on a cutting
- Temperature used
- Whether rooting powder is used
- Whether the cuttings are covered in a plastic bag

Possible dependent variables:
- Number of roots formed
- Length of the shoot formed after 10 days

Possible control variables:
- Temperature
- Carbon dioxide levels
- Humidity
- Plant species

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10
Q

Define artificial cloning

A
  • Production of large number of clones
  • Performed on industrial scale
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11
Q

Define micropropagation

A
  • Making large numbers of genetically identical offspring
  • From a single parent plant
  • Using tissue culture techniques
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12
Q

Define explant

A

Small sample of tissue taken from chosen plant

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13
Q

Describe the process of cloning plants by tissue culture

A
  • Cut plant material into explants e.g. meristem tissue, axial buds
  • Sterilise explant with bleach or alcohol
  • Place on growth medium containing glucose, amino acids, nitrates, phosphates
  • Callus made from undifferentiated cells forms
  • Auxins and cytokinin hormones added to stimulate callus formation
  • Divide callus
  • Treat with more hormones and nutrients to induce roots and shoots
  • Transfer to soil when developed into small plants
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14
Q

Why is it necessary to use an aseptic technique when carrying out micropropagation?

A

Reduces contamination by microorganism

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15
Q

Define totipotent

A
  • Cells that can differentiate into any other type of cell
  • Early embryo (zygote) cells are totipotent
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16
Q

Give the advantages and disadvantages of cloning plants by tissue culture

A

Advantages
- Quick
- Can reproduce infertile plants
- Can save rare species from extinction

Disadvantages
- Expensive and labour intensive process
- All offspring susceptible to same pest / disease (little genetic variation)
- If source plant infected with virus, all clones will also be infected

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17
Q

Compare the equipment and techniques of taking cuttings with those used for micropropagation

A

Equipment
- Cutting needs less, micropropagation needs more

Skills and staff
- Cutting needs less, micropropagation needs more

Cloned offspring
- Cutting produces less, micropropagation produces more

Aseptic technique
- Micropropagation requires more aseptic discipline

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18
Q

Define natural twinning

A
  • Splitting of early embryo naturally
  • Forms monozygotic (identical) twins
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19
Q

Define totipotent

A
  • Cells that can differentiate into any other type of cell
  • Early embryo (zygote) cells are totipotent
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20
Q

Describe the process of embryonic cloning by artificial twinning

A
  • Female animal with desirable traits selected
  • Treated with hormones to produce more egg cells
  • Egg cells fertilised naturally or by artificial insemination
  • Embryo removed from mother’s uterus at early stage of development
  • Split embryo up into individual totipotent cells
  • Split embryos developed in lab for a few days
  • Ensures embryos developing correctly
  • Implant embryos into the uterus of different animals of the same species
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21
Q

Compare the process of natural twinning and artificial twinning

A

Natural twinning
- Early embryo splits
- Two foetuses develop
- From the two halves of divided embryo

Artificial twinning
- Split in early embryo is produced manually
- Number of identical embryos replaced in surrogate mothers
- Produces a number of identical high quality animals

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22
Q

Describe the process of the somatic cell nuclear transfer (SCNT) cloning technique

A
  • Remove body (somatic) cell from animal to be cloned and remove nucleus
  • Remove egg cell from animal of same species and remove nucleus
  • Insert body cell nucleus into empty egg cell
  • Fuse with electric shock
  • Fused cell initially grown in vitro
  • Early embryos split
  • Embryos inserted into the uterus of surrogate mothers
  • Embryos divide by mitosis
  • Example: Dolly the sheep
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23
Q

Explain the similarities between artificial twinning and SCNT

A
  • Both processes involve removing eggs from an animal
  • Both involve surrogate parents
  • Both potentially produce a number of genetically identical organisms
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24
Q

Explain the differences between artificial twinning and SCNT

A

Artificial twinning
- Gametes meet outside the body (or early
embryos flushed from mother)
- Egg cell contributes all maternal DNA
- Embryos produced from gametes
- Embryos genetically related to two parents

SCNT
- Nucleus removed from somatic cell and added to enucleated egg cell in laboratory
- Egg cell only contributes mitochondrial DNA
- Embryos produced from somatic nucleus and enucleated egg cell
- Embryos genetically related to one parent

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25
Q

Give the potential uses of adult cell cloning

A
  • Produce animals with best characteristics
  • To save endangered animals
  • To grow stem cells or tissues / organs for human treatment
  • To investigate the treatment and development of disease
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26
Q

State the advantages and disadvantages of using clones to test a treatment for a disease

A

Advantages
- Genetically identical so all subjects react the
same
- Genetic variable controlled

Disadvantages
- Expensive
- Don’t see varied response to drug like in real
populations

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27
Q

Outline the arguments for and against animal cloning

A

For
- Artificial twinning enables high-yielding animals to produce more offspring than normal
- SCNT can potentially enable endangered or
extinct animals to be reproduced

Against
- SCNT is very inefficient - many eggs needed to produce single cloned offspring
- Cloned animals tend to have shortened
lifespans
- Many cloned animal embryos fail to develop
properly

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28
Q

Define biotechnology

A
  • Large-scale use of biological organisms or enzymes
  • To synthesis, breakdown or transform materials
  • To make suitable for human use
  • e.g. food, drugs
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29
Q

What are the most commonly used organisms in biotechnology?

A
  • Bacteria
  • Yeast
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30
Q

Why are microorganisms used in biotechnology?

A
  • No welfare issues
  • Large range of microorganisms - Can carry out many different processes
  • Can be genetically engineered to carry out other reactions
  • Short life cycle and rapid growth rate
  • Large quantities can be produced in short period of time
  • Nutrients required are simple and relative cheap
  • Conditions required are cheap and safe to maintain
  • Relatively low temperature, supply of oxygen and food, removal of waste products
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31
Q

Define indirect food production

A
  • Action of microorganisms on food to create a different type of food
  • e.g. acting on milk to create cheese
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32
Q

What are the disadvantages of using microorganisms to produce human food?

A
  • Require ideal conditions for process to work
  • Pathogenic microorganisms can also grow
  • Process has to be sterile
  • Ethical concerns if GM organisms used
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33
Q

How is bread made?

A
  • Yeast respires aerobically, producing CO2
  • CO2 bubbles expand when cooked, making
    bread rise
  • Yeast cells killed during cooking
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34
Q

How is beer made?

A
  • Yeast mixed with malted barley and hot water
  • Respiration (fermentation) continues for days in anaerobic conditions
  • Ethanol produced as waste product
  • Yeast eventually inhibited by rising pH
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35
Q

How is cheese made?

A
  • Milk pasteurised and homogenised
  • Mixed with bacterial cultures to separate milk into solid curds and liquid whey
  • Curds cooked and pressed to produce cheese
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36
Q

How is yoghurt made?

A
  • Skimmed milk powder added to milk
  • Pasteurised, homogenised and cooled to 47°C
  • Milk mixed with bacteria and incubated for 4-5 hours
  • Yoghurt stored in cool conditions
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37
Q

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

A
  • Microorganisms killed
  • Enzymes denatured
  • No pathogenic bacteria or competitors present
38
Q

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

A
  • To spread fat droplets evenly through milk
  • So cream doesn’t separate out
  • Creates uniform product
39
Q

Define direct food production

A
  • Production of microorganisms for direct consumption
  • e.g. Quorn (made from fungus)
40
Q

Discuss the advantages and disadvantages of using microorganisms to produce human food

A

Advantages
- Reproduce and produce protein faster than
animals and plant
- No welfare issues
- High protein content with little fat

Disadvantages
- Some microorganisms produce toxins if
conditions aren’t optimal
- Protein has to be purified to remove any toxins or contaminants
- Need sterile conditions - increases cost

41
Q

Define bioremediation

A
  • Use of microorganisms or plants
  • To break down pollutants and contaminants in soil or water
42
Q

Why is bioremediation often carried out at the site of contamination?

A
  • Area of contamination may be very large so not practical to remove contaminated material
  • Organisms involved in bioremediation grown and break down contaminants in situ
  • Living organisms used so they grow and spread
  • May be harvested and contaminants retrieved
43
Q

Give an example of bioremediation using natural organisms

A
  • Microbes will break down crude oil
  • Oil spills treated with nutrients to encourage microbial growth
44
Q

Give an example of bioremediation using GM organisms

A

Modifying bacteria to remove mercury from contaminated sites

45
Q

Why must aseptic techniques be used when culturing microorganisms in the laboratory?

A
  • Risk of mutation producing pathogenic strains
  • May be contamination with pathogenic microorganisms from environment
46
Q

How are nutrients supplied to microorganisms grown in the laboratory?

A
  • Broth - liquid
  • Agar - solid
47
Q

How is broth inoculated?

A
  • Make a suspension of the bacteria to be grown
  • Mix a known volume with sterile nutrient broth in flask
  • Stopper flask
  • To prevent contamination
  • Incubate at a suitable temperature
  • Shake regularly to aerate
  • Prevents growth of anaerobic bacteria
48
Q

How is agar inoculated?

A
  • Wire inoculating loop sterilised in bunsen flame
  • Do not touch any surfaces as it cools to avoid contamination
  • Dip cooled, sterilised loop in bacterial suspension
  • Remove lid of petri dish and streak suspension across surface of agar
  • Make sure to keep agar surface intact
  • Replace lid of petri dish
  • Hold down with tape but do not seal completely
  • Allows oxygen to still get in
  • Prevents growth of anaerobic bacteria
  • Incubate at suitable temperature
49
Q

Compare the processes of culturing bacteria in broth and on agar

A
  • Both provide nutrients, suitable pH and moisture for bacterial growth
  • Both need to be maintained at optimum temperature for growth
  • Both must be kept sterile until inoculated with microorganisms
  • Both can be shaken at intervals to aerate it
  • Agar plates remain closed once made up
  • Broth is mixed with known volumes of culture medium
  • Agar plates inoculated using sterile wire loop and culture medium
  • Numbers in broth counted using turbidity, serial dilutions, and microscope graticules
  • Numbers on agar calculated using colony counting
50
Q

Outline the four stages of microbe growth in a closed system

A
  • Lag phase
  • Microorganism adapting to new environment
  • Growing and synthesising enzymes
  • Not reproducing at maximum rate
  • Log/exponential phase
  • Microorganism reproduction at maximum rate
  • Stationary phase
  • Number of new cells formed equal to number of cells dying
  • Microorganisms produce secondary metabolites e.g. penicillin
  • Death phase
  • Reproduction almost ceased
  • Death rate increasing
51
Q

Describe the pattern of growth of microbes in a closed system

A
  • Lag phase - slow increase in population at start
  • Log phase - exponential increase
  • Rate of increase slows
  • Stationary phase - population levels off
  • Death phase - population falls
52
Q

Why is a logarithmic scale used to represent size of bacterial populations?

A
  • Difference in numbers from initial organism to maximum population size too great to
    represent using standard numbers
53
Q

Explain the factors that can prevent exponential growth in a culture of bacteria

A
  • Nutrient availability
  • Initially plenty of food
  • As nutrients used up, insufficient amounts left to support exponential growth
  • Oxygen levels
  • As population rises, so does oxygen consumption
  • Not enough oxygen for aerobic respiration
  • Temperature
  • Low temperature slows rate of growth and reproduction
  • High temperature denatures enzymes and kills microorganisms
  • Build-up of waste
  • Build up of toxic material can poison and kill cells in culture
  • Change in pH
  • CO2 produced by respiration lowers pH
  • If pH too low, enzyme activity reduces and population growth slows
54
Q

Why is the theoretical bacterial growth rate not sustainable in a closed system?

A
  • In large closed culture nothing gets in or out
  • Initially, growth can be at theoretical maximum rate as no factors are limiting
  • As culture continues, numbers increase
  • Food and oxygen are used up
  • Microorganisms run out of food or oxygen
  • Waste products build up, affecting pH
  • Denatures enzymes or poisons bacteria
55
Q

Why does putting food in a fridge prolong how long it can be eaten for?

A

Low temperatures slow rate of bacterial growth

56
Q

Why does food eventually go bad in a fridge?

A
  • Bacterial growth slows but does not stop at low temperatures
  • Bacteria grow slowly and eventually destroy food in fridge
57
Q

Why is vinegar a good preservative of foods?

A
  • Vinegar is ethanoic acid - lowers pH
  • Inhibits bacterial growth
58
Q

Why are serial dilutions used when counting bacteria?

A
  • If too many colonies present, impossible to count how many there are
  • Dilutions reduce the number of colonies on the agar plate
59
Q

How is the total viable cell count calculated when using serial dilutions?

A

Multiply number of colonies by dilution factor

60
Q

What is the equation for the theoretical maximum number of bacteria at a given time?

A

Nt = N0 x 2n
- Nt = number of cells at time t
- N0 = number of cells at time t = 0
- 2n = Number of divisions

61
Q

Define primary metabolite

A
  • Substance produced by microorganism
  • Formed as part of essential functions
  • Produced in all growth phases
  • e.g. amino acids, enzymes, ethanol (produced by anaerobic respiration)
62
Q

Define secondary metabolite

A
  • Substance produced by microorganism
  • Not essential for normal growth
  • Produced in stationary phase
  • e.g. penicillin, pigments
63
Q

What is penicillin?

A

Antibiotic

64
Q

What type of organism produces penicillin?

A

Fungus

65
Q

What stage of the microorganism’s growth curve is penicillin made?

A

Stationary phase

66
Q

Describe the process batch fermentation

A
  • Fermenter set up with fixed quantity of nutrients
  • Microorganisms inoculated into fixed volume of nutrients
  • Left alone for culture to grow
  • Culture reaches stationary phase
  • Nutrients used up, waste products build up
  • Secondary metabolites (e.g. penicillin) made
  • Process stopped before death phase
  • Product harvested
  • System cleaned, sterilised and new batch culture started
67
Q

Explain the importance of maintaining aseptic conditions in manufacturing penicillin by
fermentation

A

Avoid unwanted microbe entry
- No competition for nutrients
- No decrease in yield
- No contamination of product

68
Q

Describe the process of continuous fermentation

A
  • Microorganisms inoculated into sterile nutrient medium
  • Nutrients continually added and product regularly harvested
  • Culture kept in log phase of growth
  • Maximises production of primary metabolites or of the microorganisms
69
Q

By what process is insulin produced?

A
  • Continuous fermentation
  • GM E. Coli grown in fermentor
  • Insulin continuously harvested
70
Q

What must be kept constant in the bioreactor during continuous fermentation?

A
  • Nutrient levels
  • pH
  • Metabolic products
  • Temperature
71
Q

Explain why temperature needs to be controlled in a bioreactor

A
  • Temperature too low - microorganisms will not grow quickly enough
  • Temperature too high - enzymes start to denature, microorganisms may die
72
Q

Explain why nutrients needs to be controlled in a bioreactor

A

If food supply used up - microorganisms will start to die

73
Q

Explain why oxygen needs to be controlled in a bioreactor

A

If oxygen used up - microorganisms will start to die as cannot respire aerobically

74
Q

Explain why pH needs to be controlled in a bioreactor

A
  • If waste products (e.g. carbon dioxide) build up then pH will decrease
  • Change in pH can affect enzyme action and stop growth
75
Q

Why is it necessary for bioreactors to have stirring mechanisms?

A
  • Simple diffusion not fast enough
  • Ensures all microorganisms receive enough food and oxygen
76
Q

Describe the differences between continuous and batch fermentation

A

Continuous
- Run continuously once fermentation is started
- Sterile nutrient medium added continuously
once culture is growing exponentially
- Culture broth continually removed so product can be processed and culture volume remains the same

Batch
- Everything added at beginning in fixed volume
- Nutrients used up - microorganisms, products, and waste products build up
of nutrient medium
- May be stationary phase when secondary
metabolites formed - process stopped, products extracted, reactor cleaned, and new process begun

77
Q

Define isolated enzyme

A

Enzyme removed from host microorganism

78
Q

Explain the advantages of using isolated enzymes rather than whole microorganisms

A
  • Less wasteful
  • No microorganisms to use up substrate for metabolic processes
  • More efficient
  • Work at higher concentrations than when part of microorganism
  • More specific
  • No unwanted enzymes present
79
Q

Why are most enzymes used in industrial processes extracellular?

A
  • Easier to isolate as they are secreted
  • Relatively few produced - easier to identify
  • More robust than intracellular enzymes
80
Q

Define immobilised enzyme

A

Enzyme attached to another substance e.g. glass, gel, alginate beads

81
Q

Discuss the benefits of using immobilised enzymes for large-scale production

A
  • Enzyme can be re-used - reduces cost
  • Product uncontaminated - reduces downstream processing costs
  • Immobilised enzyme works at higher temperature - reaction can be faster
  • Immobilised enzyme works in changed pH
82
Q

Discuss the disadvantages of using immobilised enzymes for large-scale production

A
  • Reduced efficiency - immobilisation may reduce activity rate
  • Higher initial costs - immobilised enzymes more expensive
  • Higher costs of bioreactor - needs to be suitable for immobilised enzymes
  • More technical issues - reactors more complex for immobilised enzymes
83
Q

Describe the different methods of immobilising enzymes

A
  • Entrapment - e.g. in alginate beads or cellulose matrix
  • Adsorption - stuck to insoluble solid (e.g. carbon / clay / resin / glass)
  • Covalent bonding - cross-link enzymes to each other and inorganic carriers (e.g. cellulose)
  • Membrane separation - enzyme and substrate either side of partially permeable membrane
84
Q

How can immobilisation increase the effectiveness of an enzyme?

A
  • Enzymes arranged to be accessible to substrate
  • Allow continuous production by continuous flow of medium over enzyme
  • Conditions can be tightly controlled over enzyme beds
  • Changes in pH and temperature have less effect
85
Q

How can immobilisation decrease the effectiveness of an enzyme?

A
  • Immobilising enzyme may affect ability to catalyse reaction
  • Matrix or capsule can inhibit diffusion of substrate to and from active site
  • Reactions may be slowed
  • In surface immobilisation enzymes may be lost from matrix relatively easily
86
Q

What is lactose?

A

sugar found in milk

87
Q

Write an equation for the hydrolysis of milk

A

Lactose → glucose + galactose

88
Q

Explain the production of lactose-free milk

A
  • Milk poured over immobilised lactase
  • Lactose broken down into glucose and galactose
  • Suitable for people who are lactose intolerant
89
Q

What is the advantage of using lactase in an immobilised state in the food manufacturing industry?

A
  • Less likely to become denatured - higher temperatures can be used to increase rate
  • Enable enzymes to be reused - reduces costs
  • Enables reaction to flow continuously
90
Q

What is glucose isomerase immobilised enzyme used for?

A

Glucose isomerase
- Used to produce fructose from glucose
- Fructose used as sweetener in food industry

Biology Paper 2 (13 decks)

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