Differences in DNA between individuals of the same species

Question 1

What are DNA probes?

Answer 1

DNA probes are short, single-stranded sequences of DNA whose bases are complementary to a specific DNA sequence. Therefore, if the DNA sequence is present, the DNA probe will bind to it by complementary base pairing.

Question 2

Why do we use gene probes?

Answer 2

1) Screen patients for heritable conditions: you can test for presence of mutated allele.
2) Drug responses: difference people respond to the same drug in different ways, doctors can thereby prescribe the most effective drug for a particular treatment.
3) Health risks: having certain alleles may increase the risk of developing certain diseases or cancers. Identification allows individuals to take medication to lower the risk and make certain lifestyle changes to lower the risk.

Question 3

How do DNA probes work?

Answer 3

To produce a gene probe, you sequence the allele and produce the probe using a gene machine, and then use PCR to produce many probes (amplification).

Question 4

What is the process of producing DNA probes?

Answer 4

1) Probe is labelled with a fluorescent dye which can be identified by observing samples under a UV light or a radioactive isotope to make it easily detected.
2) DNA sample is bound to the bottom of the wall, you could use a DNA microarray.
3) Incubate the sample with the labelled probe (hybridisation). If the sequence complementary to that of the DNA probe is present, the probe will bind to it.
4) The well is then rinsed to wash away any unbound probes. If the target allele is present, the probe will show up.