Localization of Nucleic Acids

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Deoxyribosenucleic Acid - DNA Nucleic Acids History of Nucleic Acids Genetic Material of Organisms Structure of DNA Nucleosides and Nucleotides Nucleosides of RNA and DNA Ribonucleosides and Ribonucleotides Deoxyribonucleosides and Deoxyribonucleotides Unusual Bases in DNA

Localization of Nucleic Acids

	Localization of Nucleic Acids - DNA can be located in the cell by the Feulgen reaction, by the enzyme deoxyribonuclease and by ultra-violet light. (1) The Feulgen reaction. In 1912 Feulgen discovered that when DNA is hydrolysed with warm Schiff's reagent it becomes reddish purple in colour. Hydrolysis permits Schiff's reagent to react with aldehyde groups in the sugar deoxyribose.
By measuring the amount of light transmitted through the chromosome, quantitative estimation of DNA can be made. In 1924 Feulgen developed the fuchsin staining technique and showed that the DNA is located in the chromosomes. (2) Deoxyribonuclease. DNA can be removed by the enzyme deoxyribonuclease. (RNA can be removed by ribonuclease). After removal of DNA the nucleus does not give the Feulgen reaction.
(3) Ultra-violet absorption. The visible spectrum of light extends from 6,500A to 4,500A. Wavelengths shorter than 4,500A are called ultra-violet. Nucleic acids absorb ultra-violet light at a wave-length of 2,600A. By this method it is possible to locate DNA without staining the chromosomes. Caspersson and others have used this method to measure the nucleic acid content of nuclei.

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Single Stranded DNA Localization of Nucleic Acids Forms of DNA Characteristics of Different Forms of DNA RL Helix and Z-DNA Palindromic DNA Repetitive DNA (Satellite DNA) Satellite DNA of Drosophila Virilis