Fig. 1 shows part of a process used by a biotechnology company to make human insulin using bacterial cells. A human cell contains the insulin gene. The gene...
Question 1 Report
Fig. 1 shows part of a process used by a biotechnology company to make human insulin using bacterial cells. A human cell contains the insulin gene. The gene is inserted into a circular plasmid before the plasmid is placed in a bacterium. The bacteria are grown in large containers and insulin is removed from the culture.
Table 1 shows the mass of insulin collected after bacterial cultures were grown for different times. The culture was kept at a constant temperature and supplied with glucose as food.
| Growth time / h | Insulin collected / mg |
|---|---|
| 4 | 6 |
| 8 | 19 |
| 12 | 37 |
| 16 | 38 |
(a) What is the name of the circular DNA shown in Fig. 1? [1]
(b) Describe the change in insulin mass between 4 h and 12 h. [2]
(c) Give two reasons why the company uses bacteria rather than collecting insulin from human blood. [2]
(d) Explain why the insulin mass changed very little after 12 h. [3]
Answer Details
Genetic engineering can place the human insulin gene into bacteria so that bacterial cells produce insulin.
- The circular DNA is a plasmid. [1]
- Insulin mass increased from 6 mg after 4 h to 37 mg after 12 h. The increase was \(37-6=31\) mg. [2]
- Bacteria reproduce rapidly and large numbers can be grown cheaply. They also provide a reliable supply and the product is less likely to contain human pathogens. Any two. [2]
- After 12 h, the bacterial population has reached a maximum or its growth has slowed. Glucose or another nutrient becomes limiting, and waste products accumulate so conditions become less suitable. Consequently little additional insulin is produced. [3]
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