Biotechnology

Question 1

What is biotechnology?

Answer 1

• Uses living organisms or enzymes to synthesise, breakdown or transform materials for human use
• Materials such as cheese and yoghurt, wine and beer, bread, GE drugs like insulin and antibiotics

Question 2

What are some of the advantages of using microorganisms in biotechnology?

Answer 2

• Cost effective cultivation and mass production lead to lower consumer prices
• No animal welfare issues
• Rapid growth and reproduction
• Simple nutrient needs and can even grow on different waste materials, reducing cost
• High protein content and low fat content for food production

Question 3

What are some of the disadvantages of using microorganisms in biotechnology?

Answer 3

• Require sterile conditions, increasing costs
• Risk of contamination by unwanted microbes
• Some microorganisms may produce toxins that need to be removed
• Lack of natural flavour means additives need to be added for taste

Question 4

What is a nutrient medium in the context of culturing microorganisms?

Answer 4

• A substance that provides the essential nutrients for microbial growth
• Either in liquid form (broth) or solid form (agar)

Question 5

What factors may become limiting in bacterial cultures?

Answer 5

Nutrients, temperature, pH, oxygen, contamination and waste

Question 6

What is batch and continuous fermentation?

Answer 6

• Batch - process where microorganisms grow in a fixed volume until nutrients deplete and waste accumulates
• Continuous - method where nutrients are added and culture broth is removed continuously to maintain growth

Question 7

What are the 4 main stages of bacterial colony growth curve in a closed system?

Answer 7

1. Lag phase - cells show slow initial growth as they adapt and produce essential enzymes
2. Log/exponential phase - rapid doubling of cell numbers occurs under ideal conditions
3. Stationary phase - growth rate plateaus as nutrients diminish and waste accumulates, and cell growth is equal to cell death
4. Death phase - cell death rate exceeds growth rate due to resource limitation and build up of toxins

Question 8

How can growth rate be calculated?

Answer 8

N =N0 x 2^n
- N is number of cells in population at given time
- N0 is initial number of cells
- n is the number of generations at that point

Question 9

What is enzyme immobilisation?

Answer 9

• Involves attaching or enclosing an enzyme onto a solid support or matrix to allow reuse and to increase stability
• Allows for the recycling and reuse of expensive enzymes in various industries

Question 10

What are the advantages of enzyme immobilsation?

Answer 10

• Overall more cost effective
• Easily separated from reactants and products for greater product purity
• Improved stability as they are more tolerant of pH and temp changes, reducing denaturation chances
• Production of enzyme-free products avoids contamination of the product with the enzyme

Question 11

How is lactose removed from milk to produce lactose free milk?

Answer 11

By immobilising the enzyme lactase, which hydrolyses lactose into glucose and galactose

Question 12

What are the disadvantages of enzyme immobilisation?

Answer 12

• Higher initial costs for materials and bioreactors than for free enzymes
• Immobilisation may reduce an enzyme’s activity, leading to reduced efficiency
• Reactor systems are complex and prone to more technical problems

Question 13

What are some of the methods by which enzymes can be immobilised?

Answer 13

• Enzymes may be bound to insoluble support materials by covalent or ionic bonds
• Enzymes may be trapped in a matrix
• Enzymes may be isolated by a partially permeable membrane