8.4.13The Control of Gene Expression (A Level only)

Uses of Genetic Fingerprinting — AQA A Level Biology 7402 Revision Notes & Topical Questions

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8.4.13 Uses of Genetic Fingerprinting — AQA A Level Biology 7402 notes: Describe applications of genetic fingerprinting in forensic science, paternity, medicine, breeding and conservation.DNA taken from a crime scene (blood, saliva, semen, skin cells, hair roots) is amplified by …

tissue compatibility
genetic disorders
Exam-style question 1
Exam-style question 2
DNA database
Paternity test

Section 1 of 9Forensic science

DNA taken from a crime scene (blood, saliva, semen, skin cells, hair roots) is amplified by PCR and its profile compared with that of suspects and with a national database.

A matching pattern at many loci places a suspect at the scene, while a mismatch can exclude them or free someone wrongly convicted.

The profile of the victim may also be needed to separate victim DNA from the offender's.

The evidence shows a link to the scene, not necessarily that the person committed the crime,

and the figure quoted should be the probability of a random match.

Old unsolved cases can be re-examined when stored samples are tested with improved methods.

Section 2 of 9Paternity and relationships

Because a child inherits half of its VNTR alleles from each parent, comparing the child's bands with the mother's and a possible father's shows whether he is the biological father: all child bands not from the mother must be matched in his profile. The same principle is used in immigration cases to confirm family relationships, and to identify human remains, for example after a disaster, by comparing with relatives.

Section 3 of 9Medicine

Tissue compatibility

Checking tissue compatibility for transplant and bone marrow donors, and tracing whether donor cells have established.

Genetic disorders

Diagnosing or confirming genetic disorders when a particular allele is linked to a VNTR pattern.

Pathogens

Identifying pathogens and tracing the source of an outbreak, because strains differ in their DNA profile.

Showing which tumour cells have originated from a particular tissue.

Section 4 of 9Breeding, conservation and agriculture

Breeders use profiles to avoid inbreedingindividuals with the most different patterns are paired to maintain genetic diversity in captive populations of endangered species such as pandas.

Breeding, conservation and agriculture

Profiles can confirm the pedigree of animals such as racehorses and dogs, and identify desirable genotypes in crop plants.

Fingerprinting also detects illegal trading in protected species, by showing the origin of a sample such as ivory,

and identifies individuals in wild populations to study movement and relatedness.

Section 5 of 9Evaluating use

Advantages	Issues
Highly accurate, uses tiny samples	Contamination of samples can lead to errors
Can convict the guilty and exonerate the innocent	Storage of profiles on databases raises privacy concerns
Helps conserve species and settle family disputes	May reveal unexpected facts, such as non-paternity

Societies must decide who can be added to a database (convicted people only, or everyone arrested), how long the data are kept and who can see them. Questions often ask for an evaluation, so give both an advantage and a limitation, with an example of each.

Section 6 of 9Worked examples of interpretation and ethical points

Imagine a profile with three loci.

The mother has bands at 8 and 11 repeats at locus 1, the child has 8 and 14.

The 8 is from the mother, so the 14 must be paternal.
- (or could be either parent)

A man with bands 14 and 16 could be the father; a man with 9 and 12 could not.

Repeating this at each locus makes the conclusion much stronger, because an unrelated man would need to match at every locus.

In a criminal case, the same logic is applied to a crime scene sample: if the sample has an allele not found in the suspect or the victim,

then someone else must have been present.

If the suspect lacks an allele that is clearly present in a good-quality sample, the suspect is excluded,

since exclusion is much more certain than inclusion.

In wildlife protection, profiles from seized ivory can be matched against a reference database of elephant populations to find where the animals were killed, helping to target anti-poaching effort. In agriculture, profiles are used to verify the identity of a variety of crop, to protect breeders' rights, and to check that seeds are not contaminated by other varieties.

The retention of DNA profiles of innocent people, the possibility of familial searching (finding relatives of an offender through partial matches) and the use of data by insurers all raise concerns. Supporters argue the public benefit of solving crime justifies safeguards that are carefully controlled; critics stress privacy and the risk of errors being treated as certain.

Section 7 of 9Exam-style questions

Explain how genetic fingerprinting can be used to show that a man is not the father of a child. [3]3 marks
Suggest how genetic fingerprinting helps in the captive breeding of an endangered species. [2]2 marks

Section 8 of 9Key terms

Term	Meaning
Forensic	Using science to investigate crime
DNA database	Stored collection of DNA profiles
Paternity test	Test to identify a biological father
Inbreeding	Mating between close relatives, reducing genetic diversity
Genetic diversity	Variety of alleles in a population
Tissue typing	Matching donor and recipient markers before a transplant

Section 9 of 9Exam technique

Saying a DNA match proves guiltit shows the sample is consistent with the person, with a stated probability of coincidence.

Forgetting to remove the mother's bands when working out the father's contribution.

Thinking fingerprinting is only used in crime.

Ignoring contamination as a source of error.

Last updated: 18 October 2026