chapter 22 p2

Question 1

Cloning humans:
p1

Answer 1

Scientists have reproduced clones of primates by artificial twinning but it is proving very difficult to produce a SCNT clone of a primate.
Part of the problem seems to be that the spindle proteins needed for cell division in primate cells are sited very close to the nucleus, so the removal of the nucleus to produce the enucleated primate ovum also destroys the mechanism by which the cell divides.
This is not a problem in the ova of many other mammals because the spindle proteins are more dispersed in the cytoplasm.

Question 2

Cloning humans:
p2

Answer 2

In addition, the synchronisation of the stage of the embryo and the state of the reproductive organs of the mother have to be exactly attuned in primates - there seems to be more flexibility in some other mammals.
In recent years scientists have finally produced embryonic primate stem cell lines by SCNT.
This means it may eventually be possible to develop these potentially important therapeutic cells from human beings.

Question 3

Cloning humans:
p3

Answer 3

In most countries there is strict legislation to prevent reproductive cloning of human beings, even if the technical problems of primate cloning are overcome.
A modified version of SCNT has the potential, however, to produce human embryonic stem cells from an adult which could produce cells to be used to grow new tissues for that individual patient.
Research in this process is strictly controlled so it cannot be used for reproductive cloning - it is known as therapeutic cloning to make it clear that the end result is not to reproduce a person.
However, this form of SCNT can potentially make it possible to grow replacement organs which will not trigger an immune response in a patient and which will enable us to cure many currently life-threatening conditions.
Some people claim to have produced a cloned human baby, although they have never produced the child and the adult it was cloned from.

Question 4

The earliest recorded use of microorganisms by people was around

Answer 4

6000 BC when the Sumerians and Babylonians were using yeast to make beer.
By 4000 BC the Egyptians were using yeast to make their bread rise. These are all examples of the development and use of biotechnology over several millennia.

Question 5

Defining biotechnology:

Answer 5

• involves applying biological organisms or enzymes to the synthesis, breakdown, or transformation of materials in the service of people.
• It describes a range of processes, from the traditional production of cheese, yoghurt, wine, bread, and beer to the latest molecular technologies using DNA manipulation to produce genetically engineered microorganisms synthesising drugs such as insulin and antibiotics, and the use of biological systems to remove soil and water pollution in processes known as bioremediation
• The most commonly used organisms in biotechnology processes (bioprocesses) are fungi, particularly the yeasts, and bacteria, which are particularly useful in the newer technologies based around genetic manipulation.

Question 6

The use of microorganisms:

Answer 6

Most biotechnology involves using biological catalysts (enzymes) in a manufacturing process and the most stable, convenient, and effective form of the enzymes is often a whole microorganism.

Question 7

Microorganisms are ideal for a variety of reasons:
p1

Answer 7

• There are no welfare issues to consider - all that is needed is the optimum conditions for growth.
• There is an enormous range of microorganisms capable of carrying out many different chemical syntheses or degradations that can be used.
• Genetic engineering allows us to artificially manipulate microorganisms to carry out synthesis reactions that they would not do naturally, for example, to produce human insulin.
• Microorganisms have a very short life cycle and rapid growth rate. As a result, given the right conditions of food, oxygen, and temperature, huge quantities of microorganisms can be produced in short periods of time.

Question 8

Microorganisms are ideal for a variety of reasons:
p2

Answer 8

• The nutrient requirements of microorganisms are often very simple and relatively cheap.
  Genetic manipulation means we can modify them so that the microorganisms can utilise materials which would otherwise be wasted, making the raw materials for microorganism-controlled syntheses much cheaper than the raw materials needed for most other industrial processes.
• The conditions which most microorganisms need to grow include a relatively low temperature, a supply of oxygen and food, and the removal of waste gases. They provide their own catalysts in the form of enzymes.
  This makes bioprocesses relatively cheap compared to the high temperatures and pressures and expensive catalysts often needed in non-biological industrial processes.

Question 9

Indirect food production:
p1

Answer 9

• Microorganisms are widely used in biotechnological processes to make food such as bread, yogurt, and cheese.
• The microorganisms have an indirect effect - it is their actions on other food that is important,.
• When you eat bread you are mainly eating flour, when you eat yoghurt or cheese it is mainly milk.
• The advantages of using microorganisms in this way are all of the ones listed previously as advantages of using microorganisms in biotechnology generally.
• There are few disadvantages to using microorganisms indirectly in the production of human foods.
• If the conditions are not ideal (e.g., too hot or too cold) the microorganisms do not grow properly and so they do not work efficiently.

Question 10

Indirect food production:
p2

Answer 10

• Conditions that are ideal for the microorganisms can also be ideal for microorganisms that cause the food to go off or cause disease and so the processes have to be sterile.
• Increasingly the microorganisms used in food production have been genetically engineered, and some people have ethical issues with the use of GM organisms, although this is generally much less the case with microorganisms than with animals and plants.
• There are around 900 different types of cheese made around the world.
• Some are still made by very small-scale, traditional methods and others are produced commercially on a very large scale.

Question 11

Extra microorganisms:

Answer 11

Sometimes microorganisms are used in the same biotechnological process in more than one way.
Traditionally bacteria are used in cheesemaking (Table 1) and proteolytic enzymes are also added to the milk to help form curds and whey.
Originally these came from rennet, a substance extracted from the stomachs of calves, cows, and pigs containing the enzyme chymosin.
In modern cheesemaking, the chymosin used comes mainly from microorganisms - either from fungal sources or GM bacteria.

Question 12

process of baking

Answer 12

Question 13

process of brewing

Answer 13

Question 14

process of cheese making

Answer 14

Question 15

process of yoghurt making

Answer 15

Question 16

Direct food production:
p1

Answer 16

• People have eaten fungi for thousands of years in the form of a wide variety of mushrooms.
• In recent times, facing potential protein shortages around the world, scientists are developing more ways of using microorganisms to directly produce protein you can eat.
• It is known as single-cell protein or SCP.
• The best known SCP is Quorn™.
• This is made of the fungus Fusarium venetatum, a single celled fungus that is grown in large fermenters using glucose syrup as a food source
• The microorganisms are combined with albumen (egg white) and then compressed and formed into meat substitutes.
• Quorn™ is not only suitable for vegetarians, it is also a healthy choice as it is high in protein and low in fat.
• People are very conservative in their food choices and when the new food was launched, no mention was made of the fungi used to produce it.
• Using the term mycoprotein meant most people did not recognise what it was made of.

Question 17

Direct food production:
p2

Answer 17

• However a combination of good marketing and a good product meant that people tried Quorn™ and liked it, and it has been internationally successful as a novel protein food.
• Other attempts to make proteins from microorganisms have not yet been as successful.
• Yeasts, algae, and bacteria can be used to grow proteins that match animal proteins found in meat as well as plant proteins.
• They can be grown on almost anything, are relatively cheap and low in fat, yet none of the alternative protein sources has proved successful so far.
• People have many reservations about eating food grown on waste.
• Increasingly single celled proteins are being used to feed animals that we prefer to eat - from fish to cattle.
• If the world protein shortage continues, however, people may yet turn to eating foods made directly from microorganisms.

Question 18

advantages of using microorganisms directly to make food for human consumption.

Answer 18

Question 19

disadvantages of using microorganisms directly to make food for human consumption.

Answer 19

Question 20

Since the discovery of

Answer 20

penicillin in the 1920s, biotechnology has played a key role in the development of medicines.

Question 21

Producing penicillin:
p1

Answer 21

• The first effective antibiotic was penicillin, produced by a mould called Penicillium notatum.
• The yield of penicillin from this mould was very small.
• Commercial production of the drug in the quantities needed to treat everyone who needed it did not begin until the discovery of Penicillium chrysogenum by Mary Hunt on a melon from a market stall.
• P. chrysogenum needs relatively high oxygen levels and a rich nutrient medium to grow well.

Question 22

Producing penicillin:
p2

Answer 22

It is sensitive to pH and temperature.
This affects the way it is produced commercially.
A semi-continuous batch process is used
In the first stage of the production process the fungus grows.
In the second stage it produces penicillin.
Finally the drug is extracted from the medium and purified.

Question 23

The process uses

Answer 23

relatively small fermenters (40-200 dm*) because it is very difficult to maintain high levels of oxygenation in very large bioreactors.
The mixture is continuously stirred to keep it oxygenated.
There is a rich nutrient medium.
This medium contains a buffer to maintain ph at around 6.5
Biosensors are maintained at around 25-27 degrees C

Question 24

Making insulin:
p1

Answer 24

• biotechnology in the form of genetic engineering is important in the production of human medicines - for example, the production of human insulin.
• People with type 1 diabetes, and some people with type 2 diabetes, need regular injections of insulin to control their blood sugar levels.
• In the past, insulin was extracted from the pancreas of animals, usually pigs or cattle, slaughtered for meat.
• This meant the supply was erratic because it depended on the demand for meat - when fewer animals were killed, less insulin was available but the number of people with diabetes stayed the same.

Question 25

Making insulin:
p2

Answer 25

• There were a number of other problems.
• Some people were allergic to the animal insulin as it was often impure, although eventually very pure forms were developed which overcame this problem.
• The peak activity of animal insulin is several hours after it is injected, which made calculating when to eat meals difficult.
• For some faith groups, using pig products is not permitted.
• The development of genetically engineered bacteria which can make human insulin revolutionised the supply from the 1970s onwards.
• The bacteria are grown in a fermenter and downstream processing results in a constant supply of pure human insulin.

Question 26

Bioremediation:

Answer 26

microorganisms are used to break down pollutants and contaminants in the soil or in water.
There are different approaches to bioremediation:
. Using natural organisms
2. GM organisms

Question 27

. Using natural organisms

Answer 27

many microorganisms naturally break down organic material producing carbon dioxide and water.
Soil and water pollutants are often biological, for example, sewage and crude oil. \
If these naturally occurring microorganisms are supported, they will break down and neutralise many contaminants.
For example, in an oil spill, nutrients can be added to the water to encourage microbial growth, and the oil can be dispersed into smaller particles to give the maximum surface area for microbial action.

Question 28

. GM organisms

Answer 28

• scientists are trying to develop GM bacteria which can break down or accumulate contaminants which they would not naturally encounter.
• For example, bacteria have been engineered that can remove mercury contamination from water.
• Mercury is very toxic and accumulates in food chains.
• The aim is to develop filters containing these bacteria to remove mercury from contaminated sites.
• Often, bioremediation takes place on the site of the contamination.
• Sometimes material is removed for decontamination.
• In most cases, natural microorganisms outperform GM ones - but as our ability to change the genetic material of microorganisms increases, it may be possible to use bioremediation even more effectively than it is used now.

Question 29

Plants and bioremediation:

Answer 29

• There are some pollutants which microorganisms cannot, at the moment, remove from the soil.
• In a number of cases, special plants can be used instead.
• In the early 1970s, a tree was discovered which produced a blue sap that turned out to contain 26% nickel in its dry mass.
• Plants which can take up large quantities of metals from the ground are known as hyperaccumulators.
• The process by which hyperaccumulators take up metals from the ground is known as bioleaching.
• Suggest why plants can be used as bioremediators for heavy metal contamination but microorganisms cannot.