1) Discuss why Bacteria are useful in Biotechnology and Genetic Engineering
- Biotechnology is the application of biological organisms, systems or processes to manufacturing and service industries.
- Genetic engineering involves the transfer of genes from one organism to (usually) an unrelated species.
- Both processes often make use of bacteria because of their ability to make complex molecules (eg. proteins) and rapid reproduction rate.
Bacteria are useful in biotechnology and genetic engineering because:
- They can be grown and manipulated without raising ethical concerns.
- They have a genetic code that is the same as all other organisms, so genes from other animals or plants can be successfully transferred into bacterial DNA.
- Bacteria contain plasmids, which are circular rings of DNA, into which new genes can be inserted, removed or changed.
2) Describe the role of Yeast in production of Ethanol for Biofuel
- Yeast is a single celled fungus that uses sugar as its food source. When it respires, ethanol and carbon dioxide are produced (and energy is released).
- The ethanol produced in this reaction can be used as a biofuel (a fuel made from living organisms rather than a fossil fuel like oil, coal or gas).
- In Brazil, biofuel is partly replacing petrol as the fuel for cars and other vehicles.
- In some cases, plant material is used as the substrate for producing ethanol. It is chopped up into small pieces and mixed with yeast.
- As more crops are grown specifically to be harvested for making ethanol, less land is available for local people to grow food crops needed for survival.
3) Describe the role of Yeast in Bread-Making
- Yeast will respire anaerobically if it has access to plenty of sugar, even if oxygen is available.
- In bread making, the yeast is mixed with flour and water and respires anaerobically, producing carbon dioxide.
- The carbon dioxide produced by the yeast during respiration is caught in the dough, causing the bread to rise.
4) Describe the use of Pectinase in Fruit Juice Production
- Fruit juice is produced by squeezing the fruits to remove the juice.
- Chopping the fruit up before squeezing helps to release a lot more juice, but this does not break open all the cells so a lot of juice is lost.
- By adding an enzyme called pectinase to the chopped up fruit, more juice can be released.
- Pectinase breaks down a chemical called pectin that is found inside plant cell walls.
- Once pectin is broken down, the cell walls break more easily and more juice can be squeezed out of the fruit.
- Adding pectinase to fruits also helps to produce a clearer juice as larger polysaccharides like pectin can make the juice seem cloudy. Once they are broken down into smaller molecules, the juice becomes clearer.
5) Describe the use of Biological Washing powder containing Enzymes
- Many stains on clothes are organic molecules, eg oil from skin, protein from blood, fat and protein from food.
- Detergents that only contain soap can remove some of these stains when mixed with hot water, but it can take a lot of time, effort and high temperature to remove the stains completely.
- Biological washing powders contain enzymes are similar to the digestive enzymes produced in the alimentary canal that help to break down large food molecules.
- These washing powders can quickly break down large, insoluble molecules such as fats and proteins into smaller, soluble ones that will dissolve in washing water. They are effective at lower temperatures, meaning less energy has to be used in order to wash clothes to get them clean as washing water does not need to be heated to higher temperatures. They can be used to clean delicate fabrics that would not be suitable for washing at high temperatures.
6) Explain use of Lactase to produce Lactose-free Milk
- Lactose is the sugar found in milk.
- Human babies are born with the ability to produce lactase, the enzyme that breaks down lactose.
- Some people lose the ability to produce lactase as they get older, becoming lactose intolerant, they react badly to the lactose in milk and products made from milk.
- Milk can be made lactose free by adding the enzyme lactase to it and leaving it to stand for a while to allow the enzyme to break down the lactose.
7) Describe the role of Penicillium in the Production of Penicillin
- Penicillin was the first antibiotic discovered in 1928 by Alexander Fleming. He noticed that some bacteria he had left in a Petri dish had been killed by the naturally occurring Penicillium mould.
- The penicillium mould produces a chemical to prevent it being infected by certain types of bacteria. This chemical was isolated and named penicillin.
- Since the discovery of penicillin, methods have been developed to produce it on a large scale, using an industrial fermenter.
- Fermenters are containers used to grow microorganisms like bacteria and fungi in large amount.
- These can then be used for many biotechnological processes like producing genetically modified bacteria and the penicillium mould that produces penicillin.
- The advantage of using a fermenter is that conditions can be carefully controlled to produce large quantities of exactly the right type of microorganism.
8) State examples of Genetic Engineering
- The insertion of human genes into bacteria to produce human insulin
- The insertion of genes into crop plants to confer resistance to herbicides
- The insertion of genes into crop plants to confer resistance to insect pests – the insertion of genes into crop plants to provide additional vitamins
9) Outline Genetic Engineering using Bacterial Production of a Human Protein
- Isolation of the DNA making up a human gene using restriction enzymes, forming sticky ends.
- Restriction enzymes cut DNA at specific sites, rather than just in random places along the DNA molecule, eg. between the A and the T in the sequence GAA-TTC.
- Cutting of bacterial plasmid DNA with the same restriction enzymes, forming complementary sticky ends.
- Insertion of human DNA into bacterial plasmid DNA using DNA ligase to form a recombinant plasmid.
- Insertion of plasmid into bacteria (specific detail is not required).
- Replication of bacteria containing recombinant plasmids which make human protein as they express the gene.
10) Discuss the Advantages and Disadvantages of Genetically Modifying Crops
- Genetic modification is a faster and more efficient way of getting the same results as selective breeding.
- Improve crop yields or crop quality. This may help reduce hunger around the world.
- Introduce herbicide, insect or pest resistance into crops.
- Sterile insects could be created such as a mosquito. They would breed, which would lead to infertile offspring. This may help with spread of diseases, such as malaria, dengue fever and the Zika virus.
- GM crop seeds are often more expensive and so people in developing countries cannot afford them.
- GM crops could be harmful, for example toxins from the crops have been detected in some people’s blood.
- GM crops could cause allergic reactions in people.
- Pollen produced by the plants could be toxic and harm insects that transfer it between plants.
- Long-term health impacts not known.