How do scientists move genes between organisms and make clones?
How genetic engineering transfers a gene from one organism to another using enzymes and vectors, examples such as insulin-producing bacteria and GM crops, methods of cloning, and the benefits and ethical issues.
A focused CCEA GCSE Biology answer on genetic engineering and cloning, covering how a gene is transferred between organisms, examples such as insulin and GM crops, methods of cloning, and the benefits and ethical issues.
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What this dot point is asking
CCEA wants you to describe how genetic engineering transfers a gene from one organism to another using enzymes and vectors, give examples such as insulin-producing bacteria and GM crops, describe cloning methods, and discuss the benefits and ethical issues.
How genetic engineering works
Examples
The classic example is making insulin: the human insulin gene is put into bacteria, which then make human insulin that can be grown in large amounts to treat diabetes. GM crops can be engineered to resist pests or disease, tolerate herbicides, give higher yields, or add nutrients (such as extra vitamins).
Cloning
Benefits and ethical issues
The benefits include life-saving medicines (insulin), more and better food (GM crops), and useful copies of valuable organisms (cloning). The concerns include unknown long-term effects on health and the environment, modified genes spreading to wild plants, reduced biodiversity, and ethical questions about cloning animals.
Examples in context
Example 1. Why engineered insulin is better than animal insulin. Before genetic engineering, insulin for diabetics was extracted from the pancreases of pigs and cattle, which was slow, costly and sometimes caused reactions. Bacteria carrying the human insulin gene can be grown cheaply in huge tanks to make large amounts of identical human insulin. This is a clear benefit of genetic engineering: a reliable, plentiful supply of a human protein, and it links directly to protein synthesis, because the bacterium reads the human gene exactly as a human cell would.
Example 2. Weighing up GM crops. A GM crop engineered to resist insect pests can give farmers a higher yield with fewer pesticides, helping to feed more people. But some people worry that the modified genes could spread to wild relatives, that pests might evolve resistance, or that biodiversity could fall if one GM variety dominates. There are also concerns about a few large companies controlling the seed supply. CCEA expects a balanced answer that weighs the clear benefits against these genuine uncertainties, rather than simply being for or against.
Try this
Q1. What is a vector in genetic engineering, and give an example. [2 marks]
- Cue. Something that carries a gene into a host cell, such as a bacterial plasmid.
Q2. What is a clone? [1 mark]
- Cue. A genetically identical copy of an organism.
Exam-style practice questions
Practice questions written in the style of CCEA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
CCEA 20215 marksDescribe how bacteria can be genetically engineered to produce human insulin.Show worked answer →
Five marks for the ordered steps of gene transfer.
The human gene for making insulin is cut out of human DNA using enzymes (restriction enzymes).
A small loop of bacterial DNA, called a plasmid, is cut open using the same enzyme.
The insulin gene is inserted into the plasmid and joined using another enzyme (ligase). The plasmid acts as a vector.
The plasmid is put back into a bacterium.
The bacterium reads the human gene and makes human insulin, and the bacteria are grown in large numbers to produce insulin on a large scale.
Markers reward cutting out the gene with enzymes, a plasmid as the vector cut with the same enzyme, inserting and joining the gene, putting it into the bacterium, and the bacterium making insulin.
CCEA 20193 marksGive one benefit and one ethical concern of growing genetically modified (GM) crops.Show worked answer →
Three marks: a benefit, a concern, and clear reasoning.
Benefit: GM crops can be engineered to resist pests or disease, or to give higher yields or more nutrients, so they can produce more food and help feed a growing population.
Concern: some people worry about the long-term effects on health or on the environment, for example the modified genes spreading to wild plants, or reduced biodiversity.
A balanced answer recognises both the potential to increase food supply and the uncertainty about long-term effects.
Markers reward a clear benefit (pest resistance, yield, nutrients) and a clear ethical or environmental concern.
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Sources & how we know this
- CCEA GCSE Biology specification — CCEA (2017)