biotechnology topic 4

1. Discuss why bacteria are useful in biotech and genetic engineering including rapid reproduction rate, ability to make complex molecules, no ethical concerns, shared genetic code with other organisms and plasmids

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What is biotechnology?

Biotechnology is the use of living organisms, cells, or biological processes to make useful products or carry out useful processes.

Examples include:

• Producing medicines such as insulin

• Producing enzymes for industry

• Producing biofuels

• Genetic engineering of crops

• Fermentation in food production

Why are bacteria useful in biotechnology and genetic engineering?

Rapid reproduction rate

Bacteria reproduce by binary fission, where one bacterial cell divides into two identical cells.

Advantages:

• Population doubles very quickly.

• Large numbers can be produced in a short time.

• Useful products can be manufactured rapidly.

• Large-scale production is relatively cheap.

Under ideal conditions, some bacteria can divide every 20 minutes.

Ability to make complex molecules

Bacteria contain:

• DNA

• Ribosomes

• Enzymes

These allow them to manufacture complex biological molecules such as:

• Human insulin

• Human growth hormone

• Enzymes

• Vaccines

Genetically modified bacteria can be programmed to make proteins that they would not naturally produce.

advantages of using bacteria

Cheap to grow

• Require little space

• Reproduce quickly

• Easy to genetically modify

• Produce large amounts of product

Limitations

• Some proteins require modifications that bacteria cannot perform.

• Strict sterile conditions are needed to prevent contamination.

2. Describe the role of yeast in the production of bread, and alcohol (biofuels)

Yeast is a single-celled fungus.

It contains enzymes that carry out fermentation.

Fermentation

Fermentation is the anaerobic breakdown of glucose.

Word equation:

Glucose → Ethanol + Carbon dioxide

Yeast in bread production Process

1. Sugar in the dough provides glucose.

2. Yeast carries out fermentation.

3. Carbon dioxide gas is produced.

4. Gas bubbles become trapped in the dough.

5. Dough expands and rises.

Yeast in biofuel production adv and dis

1. Advantages

2. Plant material provides sugars.

3. Yeast ferments sugars.

4. Ethanol is produced.

5. Ethanol is purified and used as fuel.

Advantages of bioethanol

• Renewable resource

• Reduces dependence on fossil fuels

• Can lower net carbon emissions

Disadvantages

• Uses agricultural land

• Can compete with food production

• Requires energy for processing

3. Investigate the use of pectinase in fruit juice production

What is pectin?

Pectin is a structural polysaccharide found in plant cell walls.

It helps:

• Hold plant cells together

• Give fruit firmness

What is pectinase?

Pectinase is an enzyme that breaks down pectin.

Use in fruit juice production Process

1. Fruit is crushed.

2. Pectinase is added.

3. Pectin in cell walls is broken down.

4. More juice is released.

5. Juice becomes clearer.

Advantages Increased yield

More juice is extracted from the same amount of fruit.

Improved clarity

Fewer suspended particles remain.

Faster processing

Juice separates more easily.

Reduced waste

More of the fruit is used.

IGCSE enzyme principles

Pectinase works best at:

• Optimum temperature

• Optimum pH

If temperature becomes too high:

• Enzyme denatures.

• Active site changes shape.

• Activity decreases.

4. Investigate and describe the use of lactase to produce lactose free milk

What is lactose?

Lactose is the natural sugar found in milk.

What is lactase?

Lactase is an enzyme that breaks down lactose.

Reaction:

Lactose → Glucose + Galactose

Lactose intolerance

Some people do not produce enough lactase.

As a result:

• Lactose is not digested properly.

• Bacteria in the intestine ferment it.

• Symptoms include:

  • Bloating

  • Diarrhoea

  • Abdominal pain

Production of lactose-free milk Process

1. Lactase enzyme is added to milk.

2. Lactose is hydrolysed.

3. Glucose and galactose are produced.

4. Lactose-free milk is formed.

ADV and DIS

Advantages Suitable for lactose-intolerant people

Allows them to consume dairy products comfortably.

Sweeter taste

Glucose and galactose taste sweeter than lactose.

Easier digestion

No need for the body to produce large amounts of lactase.

Industrial production

Often lactase is:

• Immobilised on beads.

• Milk flows over the enzyme.

• Enzyme can be reused many times.

Advantages of immobilised enzymes

• Reusable

• Lower costs

• Easier product purification

• Reduced contamination

5.Practical investigation to support SC 3 – Investigate and describe the use of biological washing powders that contain enzymes

Common enzymes used Protease

Breaks down proteins.

Examples:

• Blood

• Egg

• Sweat stains

Lipase

Breaks down fats and oils.

Examples:

• Grease

• Butter

• Cooking oil

Amylase

Breaks down starch.

Examples:

• Gravy

• Sauces

• Pasta stains

Why enzymes are useful

They:

• Speed up stain removal.

• Work at lower temperatures.

• Reduce energy use.

Practical investigation

Aim

To investigate the effectiveness of biological washing powder.

Variables

Independent variable:

• Presence or absence of enzymes

Dependent variable:

• Amount of stain removed

Controlled variables:

• Temperature

• Time

• Amount of detergent

• Type of stain

• Size of fabric sample

Method

1. Prepare identical stained fabric pieces.

2. Place them in different detergent solutions.

3. Leave for the same time.

4. Compare stain removal.

Results

Biological detergents usually remove stains more effectively.

Advantages

• Effective stain removal

• Lower washing temperatures

• Reduced energy consumption

Disadvantages

• Enzymes can cause allergies in some workers.

• Very high temperatures denature enzymes.

6. Describe the role of Penicillium fungus in the production of the antibiotic penicillin

What is Penicillium?

Penicillium is a fungus that naturally produces penicillin.

Discovery

Penicillin was discovered by Alexander Fleming in 1928.

He observed that Penicillium mould prevented bacterial growth.

Production Process

1. Penicillium fungus is grown in large fermenters.

2. Nutrients are supplied.

3. Conditions are controlled.

4. Penicillin is produced.

5. Penicillin is extracted and purified.

What is penicillin?

Penicillin is an antibiotic.

It kills bacteria by interfering with bacterial cell wall formation.

Importance

Penicillin is used to treat bacterial infections such as:

• Pneumonia

• Skin infections

• Throat infections

Limitations

• Does not work against viruses.

• Some bacteria have developed antibiotic resistance.

7. Define genetic engineering as changing the genetic material of an organism by removing, changing or inserting individual genes

Definition

Genetic engineering is the deliberate modification of an organism's genetic material by:

• Removing genes

• Altering genes

• Inserting genes

to produce desired characteristics.

Purpose

Genetic engineering can be used to:

• Produce medicines

• Improve crops

• Increase food production

• Create disease-resistant organisms

Key idea

A specific gene is transferred from one organism to another so the recipient gains a new characteristic.

8. Outline genetic engineering using bacterial production of a human protein as an example (insulin) including terms like restriction enzymes, sticky ends, plasmid, ligase, recombinant, gene expression

Step 1: Identify the insulin gene

Scientists locate the human gene responsible for insulin production.

Step 2: Remove the insulin gene

Restriction enzymes are used.

Restriction enzymes

Restriction enzymes cut DNA at specific base sequences.

This creates:

Sticky ends

Sticky ends are short single-stranded DNA overhangs that allow DNA fragments to join together.

Step 3: Remove a bacterial plasmid

A plasmid is removed from a bacterial cell.

Plasmid

A plasmid is a small circular piece of bacterial DNA that can replicate independently.

Step 4: Cut the plasmid

The same restriction enzyme cuts the plasmid.

Matching sticky ends are produced.

Step 5: Join the DNA DNA ligase

DNA ligase joins DNA fragments together.

The insulin gene is inserted into the plasmid.

Step 6: Form recombinant DNA Recombinant DNA

DNA formed from genetic material originating from different organisms.

The modified plasmid is called a recombinant plasmid.

Step 7: Insert plasmid into bacteria

The recombinant plasmid is transferred into bacterial cells.

Step 8: Bacteria reproduce

The bacteria multiply rapidly through binary fission.

Large populations containing the insulin gene are produced.

Step 9: Gene expression Gene expression

The process by which information in a gene is used to produce a protein.

The bacterial cells:

• Read the insulin gene.

• Produce insulin protein.

• Release insulin for collection and purification.

Advantages of genetically engineered insulin

• Large-scale production

• High purity

• Reliable supply

• Lower risk of allergic reactions

• No need to obtain insulin from animals

9. Discuss the advantages and disadvantages of genetically modified crops like soya, maize and rice

What are genetically modified (GM) crops?

GM crops contain DNA that has been altered through genetic engineering.

Examples:

• Soya

• Maize

• Rice

Advantages Increased yield

More food can be produced per hectare.

Pest resistance

Some GM crops produce proteins toxic to insect pests.

Benefits:

• Less crop damage

• Higher yields

Herbicide resistance

Allows farmers to control weeds more effectively.

Disease resistance

Reduces losses caused by pathogens.

Improved nutrition

Example:

Golden Rice

Golden Rice contains extra beta-carotene, helping reduce vitamin A deficiency.

Reduced pesticide use

Less pesticide spraying may be needed.

Better food security

Higher production can help feed growing populations.

Disadvantages Environmental concerns

GM genes may spread into wild plant populations.

Loss of biodiversity

Widespread use of one crop variety may reduce genetic diversity.

Development of resistant pests

Pests may evolve resistance over time.

Economic concerns

Farmers may become dependent on biotechnology companies for seeds.