Cloning and Biotechnology

Question 1

How do plans reproduce asexually?

Answer 1

Parts of the plant replicate by mitosis from stem cells (meristem).

Question 2

How do strawberries reproduce?

Answer 2

The form runners which are horizontal stems that branch away from the plant and then form roots to reproduce asexually and form a clone.

Question 3

What is a rhizome?

Answer 3

A branching stem from the reproducing plant that grows downwards to produce the clone

Question 4

How are plant cuttings used to clone plants?

Answer 4

Cutting off non-flowering stem from the budding plant, dipping in plant hormones to encourage growth and fungicide then growing in soil.

Question 5

How is micropropagation used to clone plants?

Answer 5

Taking only a tissue culture, sterilising the sample (e.g ethanol) and growing with hormones (auxins and cytokines) first on agar until roots have developed. A callus forms and is split into cells, transferred to a new agar plate. Eventually, plantlets that form are potted in soil.

Question 6

What are the advantages of micropropogation?

Answer 6

• Rapid production of plants
• creates disease free plants
• can clone genetically modified plants.
• can clone seedless plants
• produce large numbers of rare endangered species
• can grow plants not easy to grow from seed

Question 7

What are the disadvantages of micropropagation?

Answer 7

• expensive and requires skilled workers
• if the original cells have a viral infection, all the plats produced also will
• Monocultures are grown, reducing gene pool. They are all susceptible to the same diseases

Question 8

What are a form of natural clones in animals?

Answer 8

Identical twins (monozygotic) originate from one zygote that splits into two or more to form identical offspring.

Question 9

What is embryo twinning?

Answer 9

The process produces offspring that are clones of each other but not their parents. It has been routine procedure to boost livestock yield and promote desirable characteristics. It involves the purposeful splitting of an embryo from parents of desirable characteristics into many clones. These are inserted into uterus of host mothers.

Question 10

What is somatic cell nuclear transfer?

Answer 10

-The animal to be cloned donates a somatic (body) cell (eg. from an udder)
- The egg cell is extracted from the egg donor and enucleated (its nucleus is removed by suction and discarded)
- The nucleus from the udder cell is injected into the enucleated egg cell
- The hybrid zygote cell is now treated with a small electrical current to encourage it to divide by mitosis
- The embryo is implanted into the surrogate mother for gestation and birth

Question 11

What are the advantages of animal cloning?

Answer 11

• Animals with desirable characteristics will produce more offspring than with natural reproduction
• SCNT enables genetically engineered embryos to be cloned.
• Prticular animals can be clones (family pet, race horse)
• It could be used to increase the numbers of rare and endangered animals.

Question 12

What are the disadvantages of animal cloning?

Answer 12

• SCNT is not efficient. 1 embryo is usually formed from many eggs.
• high miscarriage rate when implanting embryos from SCNT
• Animals produced by SCNT often have a shorter lifespan

Question 13

What are the advantages of using microorganisms in biotechnology?

Answer 13

• Economic = tiny so can be grown in smaller spaces than animals. Their nutrient requirement is cheaper than animals. Can be grown at low temps, making harvesting cheaper.
• Short life cycle - food production is much faster than waiting for animals to grow
• Growth requirements are basic - warmth, water, oxygen and food. Reduces cost to grow them.

Question 14

Where are microorganisms used in food production?

Answer 14

• Bread
• Brewing
• Cheese
• Yoghurt

Question 15

How is bread made using microorganisms?

Answer 15

Yeast used for baking and the CO2 from its respiration makes bread rise

Question 16

How are microorganisms used in brewing of alcohol?

Answer 16

Anaerobic respiration of yeast produces ethanol which is used to make alcoholic drinks

Question 17

How is cheese made using microorganisms?

Answer 17

Bacteria uses milk as respiratory substrate, making it into curds (solids) and whey (liquid). Curds used to make cheese.

Question 18

How is yoghurt made using microorganisms?

Answer 18

Bacteria produce ethanal or lactic acid which result in the milk forming polymers that give yoghurt a thicker and smoother texture.

Question 19

How are microorganisms involved in medicine production?

Answer 19

Penicillin and insulin. Penicllin is an antibiotic produced by mould. The fungus is grown in fermenters, stirred with oxygen and nutrients and the penicillin produced is harvested and purified

Question 20

What is bioremediation?

Answer 20

When microorganisms are used to digest pollutants and contaminants. Their growth can be encouraged (providing nutrients) to increase their population size to help break down pollution. E.g oil spillage cleaning

Question 21

List the advantages of using microorganisms in biotechnology.

Answer 21

• They grow rapidly
• They can be genetically engineered
• They can be flavoured to taste like anything
• There are no ethical concerns about growing microbes
• They are rich in protein and low in fat (beneficial for foods made from them like quorn)

Question 22

List the disadvantages of using microorganisms in biotechnology.

Answer 22

• Microbes can produce toxins if growing conditions are not carefully controlled
• Microbes must be grown in aseptic conditions
• Some people don’t like the idea of eating them
  -Microbes have no natural flavour, so additive have to be used

Question 23

How are microorganisms grown?

Answer 23

They require a growth medium (liquid nutrient broth or solid agar) that contains water and nutrients. They also require oxygen and are incubated at 25 degrees - warm enough for growth but below optimum temp to reduce risk of pathogens growing in large quantities.

Question 24

Describe aseptic techniques needed to culture microorganisms.

Answer 24

• Sterilise all equipment to kill microbes - e.g flaming metal equipment in blue flame of busen burner
• Sterilise work surfaces using disinfectant
  -Wash hands with soap to remove microbes
• Work near a Bunsen burner - convection currents constantly sterilise the air
• Only open the Petri lid slightly and only when needed

Question 25

How do you work out the number of microorganisms in a population?

Answer 25

N = N0 x 2^n
N0= initial number
n= number of divisions or generations

Question 26

What is a standard growth curve?

Answer 26

The log of the numbers of bacteria grown over time, plotted onto a graph

Question 27

What are the 4 phases of a standard growth curve?

Answer 27

Lag phase, exponential phase, stationary phase and death phase.

Question 28

What happens in lag phase of a standard growth curve?

Answer 28

• number of bacteria is lower while they adjust to their new environment. They are not reproducing at their maximum rate so population is constant.

Question 29

What happens in the exponential phase (LOG PHASE) of a standard growth curve?

Answer 29

Bacteria increase in number as every round of division doubles population size. So graph is steep.

Question 30

What happens in the stationary phase of a standard growth curve?

Answer 30

The number of bacteria growing/produced is = to number of bacteria dying so population number doesn’t increase. Because of toxin build up and lack of nutrients.

Question 31

What happens in the death/decline phase of a standard growth curve?

Answer 31

the dumber of bacteria decreases as number dying exceeds number reproduced.
-run out of nutrients
-build p of toxins like ethanol

Question 32

How can the death phase be prevented?

Answer 32

By removing the limiting factors:
-Plenty of nutrients constantly added
-Increasing oxygen availability to ensure aerobic respiration continues
- Maintaining temperature. As population of respiring bacteria increases, temperature does which could lead to enzymes denaturing.
-Removing toxins like ethanol
-buffering pH

Question 33

What is batch culture fermentation?

Answer 33

Fermentation occurs in a closed fermenter. Microorganisms and nutrients are added and left to grow for a period of time. No more nutrients added. Products are removed at the end.

Question 34

What is continuous culture fermentation?

Answer 34

In an open fermenter, nutrients are continually added and products are continually removed at a steady rate. Harder to maintain and set up the batch culture, but the growth rate is faster.

Question 35

What are the pros and cons to batch fermentation?

Answer 35

• Easier to set up and maintain
  -If contamination occurs only a single batch is lost.
  -slower growth rate than continuous fermnetation

Question 36

What are the pros and cons of continuous fermnetation?

Answer 36

• Faster growth rate than batch fermentation
  -If a single batch is contaminated, a huge amount of product is lost as there is only that batch.
• Difficult to set up and maintain

Question 37

What is an alternative to using microoorganisms?

Answer 37

Isolating and immobilising the enzymes they contain. It is more efficient and specific. Growth mediums are not needed.

Question 38

What is an immobilised enzyme?

Answer 38

The enzyme is fixed to an inert substance and the substrate is passed over it.

Question 39

What are the pros of immobilised enzymes?

Answer 39

You do not need to purify the enzyme from the product at the end as the enzyme stays attached to the inert object.
Enzymes can be readily reused, saving money.
Fixing enzymes reduces their sensitivity to temperature changes so high temps can be used to increase reaction rate without denaturing the enzymes.

Question 40

List the methods of enzyme immobilisation.

Answer 40

-Adsorption (surface immobilisation)
-Covalent bonding (surface immobilisation)
-Entrapment
-Membrane separtation

Question 41

What is Adsoption in immobilising enzymes? What are its pros and cons?

Answer 41

Enzyme binds to a support through hydrophobic and ionic interactions
Pro:
- simple cheap, and can be used with many different processes
- enzymes are readily in contact with substrate

Con:
- Enzymes can detach and be lost

Question 42

What is Covalent bonding in enzyme immobilisation and what are its pros and cons?

Answer 42

Where enzymes covalently bind to an inert substance with the help of a cross linking agent.
Pros:
- Enzyme strongly bonded so less likely to be lost.
- Enzymes readily in contact with substrate
- pH and substrate concentration will have little effect on enzyme activity

Cons:
- Cost caries
- Bonding can change active site shape, reducing effectiveess

Question 43

What is Entrapment in immobilising enzymes and what are is proes and cons?

Answer 43

Trapping enzymes in a semi-permeable membrane such as gel beads which allows the passage of substrate and product only
Pros:
- Can be used for many different processes
Cons:
- Expensive
- Difficult to entrap enzymes
- Can impact enzyme activity
- Takes time for substrate to diffuse through matrix to enzyme

Question 44

What is encapsulating in immobilised enzymes and what are the pros and cons?

Answer 44

Another type of entrapment where a partially permeable membrane serves to separate the enzymes from the substrate
Pros:
- Simple process
- Little effect on enzyme activity
- Can be used on many different processes
Cons:
- Expensice and slower ans it takes time for substrate to diffuse across the membrane to the enzyme

Question 45

What are the examples of the use of immobilised enzymes in biotechnology?

Answer 45

• glucose isomerase for the conversion of
  glucose to fructose
• penicillin acylase for the formation of semisynthetic penicillins (to which some penicillinresistant organisms are not resistant)
• lactase for the hydrolysis of lactose to glucose
  and galactose
• aminoacylase for production of pure samples
  of L-amino acids
• glucoamylase for the conversion of dextrins to
  glucose