What is the difference between dna fingerprinting and pcr

If the two DNA profiles are a match, then the evidence came from that suspect. Conversely, if the two DNA profiles do not match, then the evidence cannot have come from the suspect. DNA fingerprinting is also used to establish paternity. There are various methods for analyzing DNA to establish if two samples are the same or different. This is sometimes referred to as DNA fingerprinting. A probe is a sequence of single-stranded DNA that has been tagged with radioactivity or an enzyme so that the probe can be detected.

When a probe base pairs to its target, the investigator can detect this binding and know where the target sequence is since the probe is detectable. RFLP produces a series of bands when a Southern blot is performed with a particular combination of restriction enzyme and probe sequence. When this segment of DNA is cut by EcoR I, three restriction fragments are produced, but only one contains the target sequence which can be bound by the complementary probe sequence purple. When we examine one copy from Jack and one copy from Jill, we see that they are identical:.

When we examine their second copies of this RFLP, we see that they are not identical. Jack 2 lacks an EcoR I restriction site that Jill has 1. Therefore, when Jack and Jill have their DNA subject to RFLP analysis, they will have one band in common and one band that does not match the other's in molecular weight:.

This is a brief overview of how a Southern blot more formally called an DNA blot is performed and what type of data you can obtain form one. Southern blots allow investigators to determine the molecular weight of a restriction fragment and to measure relative amounts in different samples. Below is an example of a real Southern blot used to detect the presence of a gene that was transformed into a mixed cell population.

In this Southern blot, it is easy to determine which cells incorporated the gene and which ones did not. The figure on the left shows a photograph of a 0. Notice that the DNA does not appear as a series of discrete bands but rather as a smear.

The figure on the right is a copy of the X-ray film and reveals which strains contain the target DNA and which ones do not. Stephanie R. The DNA Fingerprint. PCR Step by Step PCR amplification includes three main steps, a denaturation step, an annealing step, and an extension step summarized in the figure below. Southern blotting using RFLPs.

Sequencing - Background RFLP often pronounced "rif lip", as if it were a word is a method used by molecular biologists to follow a particular sequence of DNA as it is passed on to other cells. Procedure: DNA genomic or other source is digested with a restriction enzyme and separated by gel electrophoresis, usually an agarose gel.

Because there are so many different restriction fragments on the gel, it usually appears as a smear rather than discrete bands. The DNA is transferred to a membrane which is a sheet of special blotting paper. The DNA fragments retain the same pattern of separation they had on the gel.

The blot is incubated with many copies of a probe which is single-stranded DNA. The probe cannot be seen but it is either radioactive or has an enzyme bound to it e. The location of the probe is revealed by incubating it with a colorless substrate that the attached enzyme converts to a colored product that can be seen or gives off light which will expose X-ray film.

If the probe was labeled with radioactivity, it can expose X-ray film directly. Advanced Search. Search Menu. Article Navigation. Close mobile search navigation Article Navigation.

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