How do scientists move genes between organisms and use DNA to identify people?
Genetic engineering as the transfer of genes between organisms, the use of restriction enzymes and vectors, examples such as insulin-producing bacteria, genetic profiling and its uses, and the issues raised.
A focused answer to the WJEC GCSE Biology section 2.3 topic on genetic engineering and profiling, covering the transfer of genes between organisms, restriction enzymes and vectors, examples such as insulin-producing bacteria and GM crops, genetic profiling and its uses, and the ethical and social issues raised.
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What this dot point is asking
WJEC wants you to describe genetic engineering and the use of restriction enzymes and vectors, give examples such as insulin-producing bacteria and GM crops, explain genetic profiling and its uses, and discuss the issues raised.
Genetic engineering
The basic steps use special enzymes and a carrier called a vector.
- A restriction enzyme cuts the wanted gene out of the DNA, leaving "sticky ends".
- The same restriction enzyme cuts open a vector (often a bacterial plasmid), so its ends match the gene.
- The gene is joined into the vector (using an enzyme called ligase).
- The vector is put into the host cell, which then follows the new gene to make the protein.
Examples of genetic engineering
- Insulin-producing bacteria. The human insulin gene is inserted into bacteria, which then make human insulin that can be collected to treat people with diabetes. This is faster and cheaper than older methods and produces human insulin rather than animal insulin.
- GM crops. Crops can be engineered with useful features, such as resistance to pests or higher yield. These can increase food production, but there are concerns about their effects on ecosystems and health.
Genetic profiling
The DNA is cut into fragments, which are separated (for example by electrophoresis) into a pattern of bands. Different people give different patterns, so the patterns can be compared.
Uses include:
- forensic science: matching DNA from a crime scene to a suspect,
- paternity testing: finding out whether a man is a child's father,
- identifying relationships and inherited conditions.
The issues raised
Both techniques raise ethical and social issues.
- For genetic engineering: concerns about the safety of GM food, possible effects on wild populations and ecosystems, and whether it is right to alter organisms' genes.
- For genetic profiling: concerns about privacy, who can access someone's DNA data, and whether it could be used to discriminate (for example by insurers or employers).
Exam-style practice questions
Practice questions written in the style of WJEC exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
WJEC style5 marksDescribe how bacteria can be genetically engineered to produce human insulin.Show worked answer →
A 5-mark sequence question.
The gene for human insulin is cut out of human DNA using a restriction enzyme. A bacterial plasmid (the vector) is cut open with the same restriction enzyme so the ends match. The insulin gene is joined into the plasmid (using another enzyme, ligase). The plasmid is put back into a bacterium. The bacterium then divides and, as it does, it follows the inserted gene to make human insulin, which can be collected and purified.
Markers reward, in order: cut out the insulin gene with a restriction enzyme; cut the plasmid (vector) with the same enzyme; insert the gene into the plasmid; put the plasmid into the bacterium; the bacterium makes insulin. Missing the vector or the restriction enzyme are common gaps.
WJEC style4 marksExplain what genetic profiling is and give two uses.Show worked answer →
A 4-mark question.
Genetic profiling (DNA fingerprinting) produces a pattern unique to a person from parts of their DNA. The DNA is cut into fragments, separated (for example by electrophoresis) to give a pattern of bands, and the patterns of different samples are compared.
Two uses: in forensic science, to match DNA from a crime scene to a suspect; in paternity testing, to find out whether a man is the father of a child (by comparing band patterns).
Markers reward: a profile is a unique pattern from a person's DNA; the comparison of patterns; two valid uses. Saying it "reads the whole genome" is not how a profile works.
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Sources & how we know this
- WJEC GCSE Biology specification (from 2016) — WJEC (2016)