RAPD

RAPD or Random Amplification of Polymorphic DNA is a type of polymerase chain reaction (PCR) used to amplify DNA from a variety of sources. The technique is used in genetics research, including genetic mapping, genetic fingerprinting, and species differentiation.

Overview

RAPD is a PCR variation that has been used to generate an arbitrary DNA sequence from a complex mixture of DNA sequences. The technique involves the use of a single, short, and arbitrary nucleotide sequence to prime on both strands of the template DNA and amplify a discrete set of loci which are randomly distributed throughout the genome.

Procedure

The RAPD procedure involves the following steps:

1. DNA extraction: The DNA is extracted from the cells of the organism under study.
2. Amplification: The extracted DNA is amplified using a single primer of arbitrary sequence in a PCR reaction.
3. Gel electrophoresis: The amplified DNA fragments are separated by size using gel electrophoresis.
4. Analysis: The resulting pattern of bands is analyzed and compared with patterns from other samples.

Applications

RAPD has been used in a variety of applications, including:

1. Genetic mapping: RAPD markers can be used to construct genetic maps of organisms for which no genetic information is available.
2. Genetic fingerprinting: RAPD can be used to generate unique genetic profiles for individuals or populations.
3. Species differentiation: RAPD can be used to differentiate between closely related species.

Limitations

Despite its wide range of applications, RAPD has several limitations. These include:

1. Reproducibility: The RAPD technique is highly sensitive to changes in PCR conditions, which can lead to variability in results.
2. Dominant nature of markers: RAPD markers are dominant, meaning they cannot distinguish between homozygous and heterozygous individuals.
3. Lack of sequence information: RAPD does not provide any information about the actual DNA sequence of the amplified fragments.

See also

• Polymerase chain reaction
• Genetic mapping
• Genetic fingerprinting
• Species differentiation