Biotechnology & Genetic Modification

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Notes

Usefulness of Bacteria

**Bacteria** are the most common microorganisms used in **biotechnology**.
They can produce **complex molecules** (e.g., enzymes for yoghurt).
They **reproduce rapidly**, so chemical production can increase quickly.
**Extended**: Few ethical concerns for large-scale growth.
**Extended**: Possess **plasmids** – small circular DNA loops ideal for gene transfer.

Biotechnology – Everyday Products

**Biofuels**: Yeast ferments glucose anaerobically to produce **ethanol** (and CO₂).
Ethanol is concentrated and blended with petrol or used alone.
Waste plant parts or dedicated crops can be used; concern over land for food.
**Bread**: Yeast produces **CO₂** by anaerobic respiration, making dough rise.
**Fruit juice**: Enzyme **pectinase** breaks down pectin in cell walls, releasing more juice and making it clearer.
**Biological washing powders**: Contain enzymes (e.g., proteases, lipases) that break down stains at lower temperatures.
**Extended – Lactose-free milk**: Enzyme **lactase** breaks down lactose for intolerant individuals.

Penicillin Production

Penicillin is an **antibiotic** produced by the fungus×Penicillium×.
Discovered by Alexander Fleming in 1928.
Produced on a large scale in **industrial fermenters**.
Fermenters control conditions: **aseptic** (steam sterilisation), **nutrients**, **optimum temperature** (water jacket), **optimum pH** (probes + acids/alkalis), **oxygenation**, **agitation** (stirring paddles), and **waste removal**.

Mycoprotein Production

Fungus×Fusarium×is cultured in fermenters under **aerobic** conditions.
Provided with **glucose syrup** as food source.
Fungal biomass is harvested and purified to produce **mycoprotein**.
Mycoprotein is a **protein-rich** food suitable for vegetarians (e.g., Quorn).

Genetic Modification – Definition & Examples

**Genetic modification** (GM) alters an organism's DNA by removing, changing, or inserting genes from another organism.
The modified organism is **transgenic**; its DNA is **recombinant**.
**Example 1**: Human insulin gene inserted into bacteria to produce insulin for diabetes.
**Example 2**: Crops (e.g., maize) with a bacterial gene for insect poison – pest resistance.
**Example 3**: Herbicide-resistant crops – only weeds die when herbicide is sprayed.
**Example 4**: **Golden rice** – genes from another plant and a bacterium produce vitamin A precursor.

Genetic Modification – Process (Extended)

1. **Restriction enzymes** cut out the desired gene, leaving **sticky ends** (unpaired bases).
2. Same enzyme cuts a bacterial **plasmid**, creating complementary sticky ends.
3. **DNA ligase** joins the gene and plasmid to form **recombinant plasmid**.
4. Recombinant plasmid is inserted into a bacterial cell.
5. Bacteria multiply in a fermenter, copying the plasmid and producing the human protein.
Bacteria are ideal because they share the **same genetic code**, have **plasmids**, and raise few ethical issues.

Bacterium showing key features: plasmids, nucleoid, flagellum. Plasmids are used in genetic modification.

Industrial fermenter with key features: agitation, water jacket, nutrient input, and harvest outlet.

Steps in genetic modification: human gene isolated with restriction enzyme, plasmid cut with same enzyme, then joined by DNA ligase to form recombinant DNA.

Practice questions

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1.Which of these statements correctly describes genetic engineering?
Easy
- AOnly breeding from crop plants that are resistant to pests.
- BAltering the DNA in crop plants so that they are resistant to herbicides.
- CUsing yeast to produce ethanol.
- DProduction of insulin in the pancreas.
2.Which of the following is a reason yeast is used to make bread?
Easy
- AIt produces ethanol.
- BIt produces lactic acid.
- CIt produces carbon dioxide.
- DIt produces oxygen.
3.What is the name of the enzyme used to produce clear apple juice?
Easy
- ALipase
- BAmylase
- CProtease
- DPectinase
4.What needs to be inserted into a bacterial cell to allow it to produce insulin to treat diabetes?
Easy
- AAn enzyme.
- BA molecule of insulin.
- CA length of DNA from a human.
- DA length of DNA from a bacterium.
5.Why are bacteria used in biotechnology?
Easy
- AThey can make complex molecules.
- BThey are found inside the human body.
- CThey reproduce slowly.
- DThey can become resistant to antibiotics.
6.What is an example of genetic modification?
Easy
- AInserting genes into bacteria
- BInserting insulin into bacteria
- CSpraying plants with herbicides
- DUsing biological washing powders
7.Which cell structure makes bacteria useful for genetic modification?
Easy
- ACell membrane
- BCell wall
- CCytoplasm
- DPlasmids
8.The diagram shows an industrial fermenter used to produce penicillin. What is a function of the part labelled X?
Medium
- AAdd oxygen to the solution
- BMaintain an even temperature throughout the solution
- CRecord the pH of the solution
- DSterilise the solution

Slides

Usefulness of Bacteria

Bacteria are the most common microorganisms used in biotechnology.
They can produce complex molecules (e.g., enzymes that turn milk into yoghurt).
They reproduce rapidly, so the amount of chemicals they produce can increase quickly.
They have few ethical concerns when grown in large numbers.
They possess plasmids – small, circular loops of DNA useful for genetic manipulation.

Which of the following is a reason bacteria are useful in biotechnology?

They reproduce slowly.
They cannot produce complex molecules.
They reproduce rapidly.
They have no DNA.

Biotechnology: Everyday Products

Biofuels: Yeast ferments glucose to produce ethanol, which can be used as fuel.
Bread: Yeast produces carbon dioxide during anaerobic respiration, making dough rise.
Fruit juice: Pectinase breaks down pectin in cell walls, releasing more juice and making it clearer.
Biological washing powders: Contain enzymes that break down stains (e.g., fat, protein) at lower temperatures.
Lactose-free milk: Lactase enzyme breaks down lactose for people with intolerance.

In bread making, yeast produces ____ which makes the dough rise.

Penicillin Production in Fermenters

Penicillin is an antibiotic produced by the fungus Penicillium.
It is grown in industrial fermenters where conditions are carefully controlled.
Key conditions: aseptic precautions, nutrients, optimum temperature, optimum pH, oxygenation, agitation.
Aseptic conditions ensure only the desired microorganism grows.
Agitation distributes nutrients, oxygen, and heat evenly.

Which of these are conditions controlled in a fermenter?

Temperature
pH
Light intensity
Oxygen levels

Mycoprotein Production

Mycoprotein is a protein-rich food made from the fungus Fusarium.
Fusarium is grown in fermenters under aerobic conditions with glucose syrup as food.
The fungal biomass is harvested and purified to produce mycoprotein (e.g., Quorn).

What is the main food source for Fusarium in mycoprotein production?

Starch
Glucose syrup
Cellulose
Lactose

Genetic Modification: Definition and Examples

Genetic modification is changing an organism's DNA by removing, altering, or inserting genes from another organism.
Transgenic organisms contain recombinant DNA (DNA from two sources).
Examples: bacteria producing human insulin; crops resistant to pests or herbicides; golden rice with extra vitamin A.

The DNA formed when genes from two different organisms are combined is called ____ DNA.

How Bacteria Produce Human Insulin

The human insulin gene is isolated using restriction enzymes, which cut DNA at specific sequences leaving 'sticky ends'.
A bacterial plasmid is cut with the same restriction enzyme, creating matching sticky ends.
DNA ligase joins the human gene and plasmid together to form a recombinant plasmid.
The recombinant plasmid is inserted into a bacterial cell.
As bacteria reproduce, they copy the plasmid and produce human insulin, which is collected and purified.

Which enzyme is used to cut DNA at specific sequences to create sticky ends?

DNA ligase
Restriction enzyme
Pectinase
Lactase

Why Bacteria Are Useful for Genetic Engineering

They have the same genetic code as other organisms, so they can read human genes and produce the same proteins.
They have plasmids, which are easy to remove, manipulate, and reinsert.
There are few ethical concerns compared to using animals.

Which of these are reasons bacteria are useful in genetic engineering?

They share the same genetic code as humans.
They have plasmids that can carry foreign DNA.
They reproduce slowly, giving time for modifications.
There are ethical concerns about using them.

GM Crops: Extended

Crops can be modified for pest resistance (e.g., Bt toxin gene from bacteria).
Herbicide resistance allows spraying to kill weeds without harming the crop.
Golden rice produces β-carotene (vitamin A) to prevent deficiency diseases.
GM crops can increase yield and reduce chemical use.

What is an advantage of genetically modifying crops to be herbicide-resistant?

The crop becomes poisonous to insects.
Herbicides kill only weeds, not the crop.
The crop produces more vitamins.
The crop grows faster.

The enzyme ____ joins the human insulin gene and bacterial plasmid together.

Summary: Biotechnology & Genetic Modification

Biotechnology uses microorganisms to make useful products (e.g., biofuels, bread, penicillin).
Fermenters control conditions for large-scale microbial growth.
Genetic modification alters DNA to produce desired traits (e.g., insulin production, pest-resistant crops).
Bacteria are ideal for genetic engineering due to plasmids, rapid reproduction, and shared genetic code.

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