21.1 Biotechnology & Genetic Modification

Tissue plasminogen activators (TPAs) are human proteins that are used as drugs to break down blood clots.

TPAs break down blood clots by activating plasminogen. Plasminogen is a protein that is always present in the blood.

When activated, plasminogen forms a protease that breaks down fibrin molecules.

Plasminogen is found in the plasma.

State what is meant by the term plasma.

[1]

State the products of the action of protease on the protein fibrin.

[1]

Extended Only

TPAs can be produced by genetically-engineered bacteria.

Fig. 1 shows some of the stages involved in genetically engineering a bacterium to make a TPA.

Fig. 1

State the name of structure A in Fig. 1.

[1]

In the flow chart, X represents the action of an enzyme on a molecule of DNA.

State the name of this enzyme.

[1]

The TPA gene is inserted into structure A.

Explain how the gene is inserted into structure A to form structure B as shown in Fig. 1.

[3]

Before TPA was made by genetically-engineered bacteria it was only available from blood donated by people.

Suggest one advantage of producing TPA by genetically-engineered bacteria.

[1]

The genetically-engineered bacteria produce mRNA that is a copy of the human TPA gene.

Explain the role of mRNA in the bacterium.

[2]

Extended only

Bacteria are often used in biotechnology as there are several advantages to their use in this field.

Outline the benefits of using bacteria in biotechnology.

Another example of a microorganism that is useful in biotechnology is the fungus Aspergillus niger. They typically grow on fruit and produce pectinase that breaks down plant cell walls. This enables A. niger to feed on the contents of the plant cells.

Pectinase is also used in the food and beverage industry.

Explain the use of pectinase in the food and beverage industry.

Extended only

Many fruits, such as lemons and limes, contain a substance called citric acid which has a wide variety of applications in the food-, cosmetics- and pharmaceutical industries.

Certain strains of A. niger can be used to produce citric acid on an industrial scale by the aerobic breakdown of glucose at pH levels of between 4 and 6.5. The fungus is cultured in large industrial fermenters where conditions are kept at an optimum.

Describe and explain the conditions that should be controlled in the fermenter to ensure optimum production of citric acid.

Extended only

Roundup™ is active against a very wide variety of plants.

Monsanto also developed a range of genetically-modified crop seeds that were resistant to Roundup™ by inserting a gene from a species of soil bacterium.

Suggest two possible ecological risks of planting these genetically-modified seeds.

Bacteria are useful in biotechnology and genetic engineering.

Fig. 1 shows a photomicrograph of a bacterium. 

Fig. 1

State the name of the process that is taking place in Fig. 1. 

Extended Only

Write the formula that would be used to calculate the actual width of the bacterium.

[1]

The actual width of the bacterium is 0.0008 mm.

Convert this value to micrometres (μm).

[1]

Extended Only

Genetically modified bacteria can produce human insulin. 

[1]

(ii)     Insulin is a protein.

Describe the process of using bacteria in genetic engineering to produce human proteins.

[5]

Extended Only

Genetically modified bacteria are often grown in fermenters.

[2]

 State three conditions inside a fermenter that are measured and controlled.

State the name of one commercial product, other than insulin, that is made in fermenters.

[1]

Extended Only

Crop plants can also be genetically modified. 

Describe the advantages of genetically modifying crops.

A factory uses biotechnology to process apples.

Some of the apple juice is mixed with yeast and used to make ethanol.

(i)      State the type of respiration in yeast that produces ethanol.

[1]

State the name of the substance in apple juice that is converted to ethanol by yeast.

The yeast uses enzymes to produce ethanol.

Define the term enzyme.

[2]

Fig. 1 shows apparatus used to find the best (optimum) temperature for making ethanol.

Fig. 1

         The same apparatus was used at different temperatures.

         The rate of ethanol production was compared by counting the number of bubbles of gas produced by the yeast and                    apple juice mixture per minute.

         State the name of the gas produced by the yeast in Fig. 1.

Fig. 2

          Calculate the increase in the rate of reaction from 20 °C to 25 °C in Fig. 2.

          Give your answer in bubbles per minute.

[1]

State the optimum temperature for the reaction shown in Fig. 2.

Give your answer in °C.

[1]

The cut surface of an apple usually turns brown when exposed to air. This is caused by enzymes.

Three slices of apple were given different treatments and were then exposed to air for 30 minutes.

Table 1 shows the treatments and appearance of the apple slices.

Table 1

Suggest why slice B and slice C did not turn brown after 30 minutes.

The enzyme pectinase is used in industry for the production of apple juice.

Explain why pectinase is used when making apple juice.

Hygienic conditions are required in an apple juice factory.

Describe three precautions workers should take to ensure that good food hygiene is maintained in the apple juice factory.