Genetic Modification (Cambridge O Level Biology)

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. 

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]

Genetically modified bacteria can produce human insulin. 

[1]

(ii)     Insulin is a protein.

[5]

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]

Crop plants can also be genetically modified. 

Describe the advantages of genetically modifying crops.

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]

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]