Structure Of DNA: The Double Helix

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Structure of DNA: The Double Helix
Introduction:
DNA stands for DeoxyriboNucleic Acid. It is a type of Nucleic Acid, which has deoxyribose sugar in it instead of ribose. DNA has a double helical structure. By double helix, the meaning is two strands of polynucleotide running parallel and coiled around each other through hydrogen bonding. DNA is hereditary material in all the living organisms on this planet. The basic mystery behind its heredity nature resides in the same double helical structure. The double helix enables it to get replicated in a semiconservative manner. The one strand acts as a template to form another strand around it and the process goes on. The discovery of this double helical structure proved to be a milestone in the history
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DNA has short segments, which are called genes. The transcription of these genes gives the mRNA fragments, which, after translation, gives active product like proteins or other forms of RNAs.
Briefly, it can be said that DNA is a basic heredity material in most of the organisms on this planet. Structure of DNA:
The double helical structure of DNA has been discovered in 1953 by the collective efforts of many scientists but two most important names are Watson and Crick (Watson &
Crick, 1953). The structure is necessary to discuss here before explaining its importance in the normal functioning and development of organisms along with its historical impact on the understanding of humans about the mysteries behind heredity. The main features of double helix of DNA can be summarized as follows.
· The first thing to consider is the primary structure of DNA. The polynucleotide strands, which wound around each other, can actually be broken down into simpler subunits or monomers. These monomers are called nucleotide. A nucleotide has three main components. These are a sugar molecule, a nitrogenous base and a phosphate group. The three components together make a
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Watson is a biologist and Crick was a physicist. Both researchers used the data pioneered by other scientists about DNA and proposed the three dimensional structure by joining the puzzles, which were never sorted out before (Pray, 2008). Due to the same reasons, the whole discovery of the double helix can be divided into four main stages.
1. The discovery of DNA and its identification as a genetic material
2. Phoebus Levene’s investigations about the structure of DNA
3. The development of Erwin Chargaff’s rules about the number of nitrogenous bases in DNA
4. The double helical model development by Watson and Crick
The Discovery of DNA as genetic material:
A Swiss biologists and physicist, Friedrich Miescher, discovered nucleic acids in 1869.
On that time, not enough data was available about the exact chemistry of this substance.
Miescher did not intend to isolate it. He was trying to isolate the protein components of human white blood cells and got a whitish substance, which had acidic nature due to high phosphate ratio than proteins and which was also resisted to get degraded under

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