Question

RFLP analysis is a technique that
(a) uses hybridization to detect specific DNA restriction fragments in genomic DNA
(b) measures the transfer frequency of genes during conjugation
(c) used to detect genetic variations at protein loci
(d) is used to amplify genes for producing useful products

Answer 1

Hint: The full form of RFLP is Restriction Fragment Length Polymorphism. As understood from the term, this technique involves using restriction enzymes that detect any change in the sequences of DNA.

Complete answer:
RFLP analysis makes use of the variations in the homologous DNA sequences, known as polymorphisms. In this technique, DNA from the organisms that are required to be distinguished is isolated.
- The desired DNA fragment is amplified by PCR and digested by restriction enzymes.
- As restriction enzymes have a particular cleavage site, a mutation in the DNA sequence will not create cleavage and thus the DNA fragment lengths in the normal and mutated samples obtained after digestion will be different.
- The length can be analyzed by agarose gel electrophoresis (AGE). The DNA in the gel is denatured to become single- stranded from double- stranded and subjected to Southern blotting on a nylon membrane.
- The nylon membrane is then exposed to a solution containing radioactive complementary nucleotide probes that hybridize to specific sequences of DNA. An X- ray of this film is taken, thus creating an autoradiogram. This helps us to find out the polymorphisms in the samples of DNA.
- RFLP has been used as an important tool in genome mapping, localization of genes for genetic disorders, paternity testing, etc.
- Simply put, the variations in the restriction DNA fragment/fragments length between individuals of the same species are called RFLP.
So, the correct answer is ‘(a) uses hybridization to detect specific DNA restriction fragments in genomic DNA’.


Note:
- RFLP analysis has been developed not only for humans but also for mice and plants like maize, tomato, rice, etc.
- RFLP analysis is a dated technique and is being phased out for newer and simpler methods due to the time taken for the analysis to occur with multiple steps such as probe labeling, DNA fragmentation, electrophoresis, blotting, hybridization, washing, and autoradiography.