Question

Feulgen reaction of DNA is due to:
A.Aldehyde produced by acid hydrolysis
B.Removal of RNA but not DNA
C.Phosphoric acid carbohydrate and nitrogen bases
D.Phosphoric acid

Answer 1

Hint: The Feulgen reaction was discovered by Robert Fuelgen. It is a staining technique to use in the study of various tissues. It helps in identifying the DNA and chromosome among the various components of a cell. It makes the identification easier.

Complete answer:
DNA is Deoxyribonucleic acid is a chemical structure that carries the genetic information of human beings from one generation to another generation. DNA consists of 2 strands that are interlocked to each other and form a shape called a double helix. The double-helical structure of DNA was given by Watson and Crick. This double helix is held together by a hydrogen bond between nitrogenous bases and other strands. Feulgen reaction is acid-catalyzed. The purine base is removed from deoxyribose that leads to the formation of the aldehyde group.

Now let us understand the steps of the Feulgen reaction.
1.This technique was discovered by Robert Feulgen.
2.It is used in histology to identify DNA and chromosomes.
3.Feulgen technique consists of selectively staining DNA under controlled conditions.
4.The reaction of Feulgen typically consists of 2 steps.
5.In step one, the fixed material is treated for 8-10 with 1N hydrochloric acid in an incubator at about 60 degrees Celsius.
6.In step two the incubated material is transferred immediately to the Schiff's reagent at room temperature until the tissue reflects purple color.
7.Once the material is stained purple it is squashed in acetocarmine.
8.Removal of purine bases is done from DNA with the help of acid hydrolysis.
9.Since RNA is not stained by HCl, this makes the reaction only DNA specific.

Hence, the correct answer is option (A)

Note: Feulgen technique consists of selectively staining DNA under controlled conditions. The reaction of Feulgen typically consists of 2 steps. In step one, the fixed material is treated for 8-10 with 1N hydrochloric acid in an incubator at about 60 degrees Celsius. In step two the incubated material is transferred immediately to the Schiff’s reagent at room temperature until the tissue reflects the purple color.