Cloning and biotechnology

Question 1

What is the process plants use to form natural clones?

Answer 1

Vegetative propagation

Question 2

What are 4 types of vegetative propagation?

Answer 2

Runners - strawberry plants - roots develop where runner hits the ground
Tubers - potatoes - underground stems swell with nutrients and develop into new plants
Bulbs - daffodils - Leaf bases swell withe nutrients, buds develop into new plants
Rhizomes - marram grass - underground stems develop buds and form new vertical shoots

Question 3

What is micropropagation and when is it particularly useful?

Answer 3

Use of tissue culture to produce many artificial clones of a plant
Desired plant is rare, produces few seeds, does not readily produce natural clones, has been genetically modified, is required to pathogen-free

Question 4

Briefly describe the stages of micropropagation

Answer 4

Explant (small sample of meristem tissue from shoot tips) removed and sterilised (e.g. in ethanol)
Sterilised explant placed in culture medium (nutrients and hormones, e.g. auxins and cytokinins)
Explant cells divide and form mass of undifferentiated cells called a callus
Callus transferred to a new culture medium, containing hormones that encourage differentiation and shoot growth
Developing plantlets transferred to soil

Question 5

What are advantages of artificial cloning in plants?

Answer 5

Rapid production
Seedless, sterile crop plants can be produced (e.g. seedless grapes) - meet demands of consumers
Genetic makeup of propagated plants is known and desired traits can be retained in clones
Way of increasing numbers of rare or endangered plants
Increasing numbers of GM plants

Question 6

What are disadvantages of artificial cloning in plants?

Answer 6

Expensive and requires skilled workers

Lack of genetic variation means all clones vulnerable to same diseases or environmental change - monoculture

Question 7

Give examples of natural cloning in animals

Answer 7

Hydra - generate buds that develop into clones
Starfish - form from fragments of an original animal
Monozygotic twins (identical) - early embryo splits to form 2 separate embryos

Question 8

What are the 2 types of artificial cloning in animals?

Answer 8

Embryo splitting (mimicking natural twinning process)
Somatic cell nuclear transfer (SCNT)

Question 9

Describe the process of embryo splitting to produce artificial clones

Answer 9

Female with desired trait treated with hormones so she super-ovulates)
Sperm from male with desired traits used to fertilise egg from a female with desired traits by artificial insemination or in vitro fertilisation)
Embryo split into several smaller embryos (totipotent) and grown in a lab
Each embryo is implanted into a surrogate mother, who has been prepared by hormone treatment (e.g. thickening walls of the uterus)
Offspring are clones of each other, share 50% of alleles with father and 50% with mother

Question 10

Describe the process of somatic cell nuclear transfer to produce artificial clones

Answer 10

Nucleus from adult somatic (body) cell transferred into an enucleated egg (lacking own nucleus) using electrofusion (mild electric shock fuses the nucleus and ovum and causes division to begin)
Resultant embryo transferred into surrogate mother
Offspring clones of original body cell (mitochondrial DNA from egg donor
e.g. Dolly the sheep

Question 11

What are the pros of animal cloning?

Answer 11

Embryo splitting enables many more offspring to be produced from the best farm animals
SCNT has potential to reproduce specific animals, such as pets and rare extinct animals

Question 12

What are the cons of animal cloning?

Answer 12

SCNT is very inefficient (high failure rate)

Cloned animals may have shortened lifespans or health problems

Question 13

What is biotechnology?

Answer 13

Exploitation of organisms and biological processes in industry, food science, agriculture, or medical science

Question 14

Describe uses of microorganisms in food production

Answer 14

Brewer’s yeast - alcohol production through anaerobic respiration
Baker’s yeast - CO2 produced by fungus makes bread rise
Cheese and yoghurt production - Lactobacillus bacteria
Mycoprotein (meat substitute - Quorn) - Fusarium fungus
Fruit juice - pectinase breaks down pectin in fruit and releases juice - pectinase enzyme from A. niger fungus

Question 15

Describe uses of microorganisms in drug production

Answer 15

Penicillin antibiotic (secondary metabolite) produced by Penicillium fungus
Insulin produced by GM E. Coli bacteria

Question 16

Describe a use of microorgansims in bioremediation

Answer 16

Use of various bacteria and fungi in water treatment, e.g. after pollution or oil spills

Question 17

What characteristics make microorganisms useful in biotechnology?

Answer 17

Fewer ethical issues - no welfare issues as associated with use of animals
Shirt life cycle - reproduce rapidly and large numbers can be produced in a short amount of time
Genetic engineering of bacteria relatively easy
Simple and cheap nutrition requirements - can often be grown on waste materials
Fewer energy requirements - most only require low temperatures

Question 18

What are the 4 stages of bacterial populations during their culture?
What are the axes on the graph labelled?

Answer 18

Lag phase, exponential phase, stationary phase, death phase

Log of numbers of bacteria, time

Question 19

What occurs during the lag phase?

Answer 19

Genes for important enzymes transcribed, bacteria adapt to their new environment

Question 20

What occurs during the exponential (log) phase?

Answer 20

Rate of reproduction close to maximum and population size increases at an exponential rate

Question 21

What occurs during the stationary phase?

Answer 21

Rate of reproduction and death occurring at the same rate (maximum population size has been reached) - equivalent to carrying capacity in a natural environment

Question 22

What occurs during the death phase?

Answer 22

Rate of death exceeds rate of reproduction due to nutrients being exhausted, waste products being produced.

Question 23

Give some limiting factors that affect exponential growth

Answer 23

Nutrient levels, oxygen availability, temperature, pH, waste products

Question 24

What are primary metabolites?

Answer 24

Substances formed as part of the normal growth of microorganisms (e.g. proteins, enzymes, ethanol)

Question 25

What are secondary metabolites?

Answer 25

Produced principally in stationary phase when bacteria are under stressful conditions. Not all microorganisms produce secondary metabolites. (e.g. antibiotics)

Question 26

What types of techniques are used to keep nutrient media sterile?

Answer 26

Aseptic techniques, e.g. preventing contamination of cultures from the air, using a sterilised inoculating loop to transfer bacteria to agar
Inoculation in this case is the addition of microorganisms to a culture

Question 27

Why is temperature controlled in bioreactors?

Answer 27

To maintain the optimum temperature for enzymes

Question 28

Why are nutrients and oxygen controlled?

Answer 28

Medium is mixed and stirred to ensure an even distribution of respiratory substrates and oxygen. levels can be monitored and extra nutrients and oxygen are added if necessary

Question 29

Why is asepsis controlled?

Answer 29

Prevent contamination from other, unwanted microorganisms

Question 30

What happens to population size in batch culture vs continuous culture?

Answer 30

Batch - waste and population builds up, process halted before death phase - secondary metabolites
Continuous - Population and waste removed continuously to maintain population size - primary metabolites and GM products, e.g. insulin

Question 31

What are the advantages of using immobilised enzymes?

Answer 31

Less downstream processing (once reaction has occurred, enzymes do not need to be separated from the product)
Enzymes can be immediately reused (saving money and time)
Enzymes can be more protected and therefore more stable and reliable
More efficient using isolated enzymes than whole organsims

Question 32

What are the disadvantages of using immobilised enzymes?

Answer 32

More expensive and time-consuming to set up

Sometimes less active and therefore less efficient than freely dissolved enzymes

Question 33

How can enzymes be immobilised by surface immobilisation?

Answer 33

Adsorption - attachment to inert material (e.g. glass or alginate beads) - cheap, risk of leaking, slow
Covalent and ionic bonding - covalent bonds with silica gel or clay particles, or cross-linked to each other, ionic bonds form with cellulose or synthetic polymers - little enzyme leakage, enzymes’ active sites very accessible for substrates - cost varies

Question 34

How can enzymes be immobilised by entrapment?

Answer 34

In matrix - enzymes trapped in a gelatin or cellulose matrix
Membrane entrapment - separation from substrate solution using a semi-permeable membrane - active sites unaltered by immobilisation, expensive, active sites less accessible for substrates, diffusion and collection of product can be slow

Question 35

Give 2 examples of immobilised enzyme use

Answer 35

Lactase - breaks lactose into glucose and galactose to produce lactose-free milk
Glucose isomerase - used to produce fructose, used as a sweetener in food and drink