DNA Test Methods - Hybridisation

View the full Interactive Tutorial at:
http://www.phgfoundation.org/tutorials/dna/2.html

Often, a particular piece of DNA (or RNA) of interest needs to be detected in a mixture containing many pieces with different sequences.

One way to do this is by hybridisation. Hybridisation refers to the process in which two complementary pieces of DNA (or a piece of DNA and a piece of RNA) anneal to form a double-stranded molecule.

The piece of DNA or RNA used to detect complementary sequences is often called a probe. If the probe is labelled, for example by making it radioactive or fluorescent, then any pieces of DNA or RNA that it hybridises to will also be labelled and can be detected.

Before it can be used for hybridisation, a double-stranded DNA molecule must be separated into single-stranded DNA molecules, or denatured. Denaturing is usually achieved by heating the sample; when it is cooled, the resulting single-stranded molecules will hybridise to complementary molecules in the mixture, including those of the labelled probe.

Category:

Science & Technology

Tags:

• phgfoundation
• interactive
• tutorials
• dna
• test
• methods

[iLOVENATURE2011]

brief yet informative video about DNA testing and results. TY

[MaxWa]

@SeoulSarah & @baba7107

The chances are the strand of interest (hereafter SOI) will reanneal to both the original complementary strand and the probe. But if the probe is at a much higher concentration than the original DNA, more probe will anneal to SOI DNA rather than the complementary strand. Therefore, there will be a net fluorescence/radioactivity easy to isolate.

Another method is to use PCR with a primer specific to the SOI, giving a single predominant product.

Hope this helps :)

[blazflare]

People use High Resolution Melt Analysis to test for DNA nowadays..

[CaminDaR]

@baba7107 because the complementary strand IS the strand of interest. The probe is a DNA strand of KNOWN sequence. So the probes that you choose to use in this technique will bind specifically with the segment of DNA that you are looking for.

[SeoulSarah]

@baba7107 That's a very good question! Did you ever found out the answer?

[bowelazop]

thank!!!! very good video

[Rigelcentauri58]

Very Good!!!, in only one minute you teach about this technic.

Your capacity for teaching is outstanding. Congratulations!!

[baba7107]

@farahabdullah why the probe suddenly attaches to the strand of interest why not the complementary strand of the strand of interest anneal again

[mehrshadpiano]

very helpful . nice job. now I got that .

[som3aelgen]

thanks a lot