DNA sequencing and DNA profiling are related technologies, but they answer different questions. Sequencing tells us the order of bases. Profiling compares patterns at selected DNA regions to infer similarity, difference and inheritance links in populations.
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A student says, "DNA profiling and DNA sequencing are basically the same thing because both use DNA. If you have a DNA profile, you already know the exact base order of the whole genome."
Before reading on, explain why that statement is weak. What does sequencing determine that profiling usually does not?
Sequencing asks: what is the exact nucleotide order in this DNA region or genome?
If the sequence is known, specific mutations, SNPs and gene variants can be identified directly. This is powerful for investigating inherited disorders, comparing species, and analysing how populations differ at the DNA level.
DNA profiling does not normally read the full base order of the whole genome. Instead, it compares patterns at selected DNA regions that vary between individuals. This allows samples to be distinguished or matched more efficiently.
Patterns in selected marker regions rather than the entire genome sequence.
Similarity, difference, and possible inheritance relationships between samples.
It does not automatically reveal the exact complete base order for the whole genome.
Both technologies can contribute to understanding inheritance patterns in populations, but the strength of the conclusion depends on what data was collected. Sequencing offers more direct molecular detail. Profiling offers efficient comparison at specific markers.
For Module 5, the important idea is not a narrow forensic storyline. The important idea is how these tools are used to investigate inheritance across groups.
Identify what information the technology produces.
State whether it determines exact base order or compares marker patterns.
Link the technology to inheritance patterns, relatedness or disease studies.
Keep the conclusion matched to what the technology can really show.
DNA sequencing determines the exact order of nucleotide bases in a DNA sequence.
DNA profiling compares patterns at selected DNA regions to distinguish or relate samples.
Sequencing reads base order directly, while profiling matches or compares marker patterns.
Both technologies help investigate inheritance patterns in populations, including relatedness and inherited disease risk.
Look back at what you wrote in the Think First section. What has changed? What did you get right? What surprised you?
For each statement below, decide whether it matches DNA sequencing or DNA profiling:
a) determines the base order of a gene
b) compares selected marker patterns between samples
c) can identify a specific inherited base change directly
A researcher wants to compare whether a disease-linked variant is present in two populations. Explain why sequencing may be more useful than profiling for this question.
1. What does DNA sequencing determine directly?
2. What is the main function of DNA profiling?
3. A scientist wants to identify the exact base change responsible for an inherited disorder. Which technology is most appropriate?
4. Which statement best compares sequencing and profiling?
5. Why is it weak to treat DNA profiling as a full genome sequence?
6. Define DNA sequencing and DNA profiling, and state one key difference between them.
3 marks
7. Explain why DNA sequencing is useful for investigating inherited disease variants in a population.
4 marks
8. A study uses DNA profiling to compare samples from several families in a population. Explain what kind of information profiling can provide, and one important limitation compared with DNA sequencing.
5 marks
Determines the exact order of nucleotide bases.
Compares selected DNA marker patterns between samples.
Both technologies support inference about inheritance patterns, relatedness and disease variants in populations.
Return to the claim from the start of the lesson and rewrite it using the correct distinction between sequencing and profiling.
1. B - Sequencing determines the order of nucleotide bases.
2. B - Profiling compares selected DNA patterns between samples.
3. A - Exact base changes are identified directly by sequencing.
4. C - Sequencing reads base order, while profiling compares selected patterns.
5. B - Profiling does not normally provide the full genome base order.
DNA sequencing is the determination of the nucleotide base order in DNA. DNA profiling is the comparison of selected DNA marker patterns between samples. A key difference is that sequencing reads base order directly, while profiling usually compares patterns at selected regions rather than the full sequence.
DNA sequencing is useful because it identifies the exact nucleotide order and can reveal specific inherited variants or mutations associated with disease. This allows researchers to detect whether a disease-linked base change is present in individuals or populations and compare how common the variant is across groups.
DNA profiling can provide information about whether samples share similar selected DNA marker patterns, which can support inference about relatedness or inheritance links between individuals or families. A major limitation is that profiling does not usually give the full exact base order, so it cannot identify every specific variant in the same way that sequencing can.
Tick this once you can distinguish DNA sequencing from DNA profiling and explain how each helps investigate inheritance patterns in populations.