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A labelled probe detects complementary sequence under controlled conditions. Interpret what that match means for an allele, a risk prediction and a person’s choices.
What you'll be able to do
A DNA probe is a short labelled sequence designed to bind to a complementary target. The sample DNA is made accessible as single strands and the probe hybridises where suitable base pairing occurs. A fluorescent or other detectable label reveals retained probe binding after appropriate treatment and washing.
Binding conditions affect specificity: very similar sequences may also bind under less stringent conditions. Positive and negative controls and a known reference help determine whether a signal reflects the intended target. A probe is a detection tool, not an enzyme that automatically repairs the allele it finds.
A probe can help identify a particular allele associated with a heritable condition or drug response. Whether that allele predicts disease depends on dominance, penetrance, other genes and environmental influences in the case provided. The assay’s accuracy also limits the conclusion.
A negative result for one allele does not exclude every possible genetic cause of a similar condition. A positive risk marker does not always mean inevitable disease. Distinguish finding a sequence from understanding its effect on protein, cell function and phenotype.
Genetic counselling can help individuals understand the meaning, uncertainty and family implications of results. Personalised-response information may help evaluate which intervention is more likely to be effective or cause adverse responses, but the strength of the supporting association and functional evidence matters.
Consider informed consent, confidentiality, potential anxiety, uncertain findings, access and the implications for relatives. Screening programmes need evidence on false positives, false negatives and useful consequences of finding the result. Present benefits and limitations together rather than assuming more sequence information always gives a clear decision.
Try each question before opening the worked response. Use precise biological terms, connect each cause to its effect, and check units and assumptions when interpreting data.
Common mistakes to avoid
Key takeaways
Test yourself
Answer a few questions, then review anything you missed.
Start with the quiz above to check the key ideas. You can also choose another topic from the practice library.