Structure of DNA And RNA

Introduction

  • DNA or deoxyribonucleic acid is a group of molecules responsible for transmitting genetic instructions or hereditary materials from parents to offspring. DNA is an organic compound with a unique molecular structure and is found in all eukaryotic cells and prokaryotic cells
  • DNA is a nucleic acid in the cells which functions as the original blueprint for the synthesis of proteins. It contains phosphate, a unique sequence of the nitrogenous bases guanine (G), thymine (T), adenine (A), cytosine (C), and sugar deoxyribose
  • RNA refers to ribonucleic acid, which assists in the synthesis of proteins in the human body. Nucleic acid is credible for the generation of new cells in our bodies. It is generally achieved from the molecule of DNA. RNA matches the same as DNA, the only distinction being that RNA has one strand while the DNA has double strands. RNA comprises only one ribose sugar molecule in it. Therefore, it is named ribonucleic acid

Structure of DNA and RNA

  • The structure of DNA can be understood as a twisted ladder. It is a nucleic acid that is composed of nucleotides. The DNA molecule is composed of units called nucleotides, which comprise three distinct components, such as phosphate groups, nitrogen bases, and sugar
  • The phosphate groups and sugar link the nucleotides together to form each strand of DNA
  • The four kinds of nitrogen bases are Guanine (G), Adenine (A), Cytosine (C), and Thymine (T). They pair together in the following way: Cytosine (C) with Guanine (G) and Adenine (A) with Thymine (T), and they are essential for the DNA’s double helix structure that resembles a twisted ladder. The order of the nitrogenous bases determines the DNA’s instructions or the genetic code
  • The two threads of DNA run in opposing directions. These threads are held jointly by the hydrogen bond between the two corresponding bases. The threads are helically twisted, where each thread forms a right-handed coil and ten nucleotides devise a single turn. Every helix consists of a pitch of 3.4 nm. Therefore, the interval between two successive base pairs is 0.34 nm
  • The DNA coils up and forms chromosomes where each chromosome contains a single molecule of DNA in it. Altogether, human beings have around 23 pairs of chromosomes in the nucleus of cells
  • RNA has all the components similar to that of the Deoxyribonucleic acid but with two main distinctions within it. RNA has similar nitrogen bases known as Guanine, Adenine, Cytosine as in the DNA besides the uracil that replaced the thymine. Adenine and uracil are regarded as the crucial and primary building components of RNA, and two of them shape base-pair with the support of two hydrogen bonds
  • The structure of RNA resembles a hairpin and, like the nucleotides, molded in this ribonucleic material in DNA. Nucleosides are the phosphate groups that occasionally also help generate nucleotides in the deoxyribonucleic acid

Classification of DNA and RNA

The classification of DNA based on the structure is as follows:

    1. A-DNA: A-DNA or also shown as A-form DNA, is a right-handed double helix structure form with a mean propeller twist of +18°. It has 32.7° rotation per base pair (bp), and 11 mean bp per turn. It has a +19° inclination of bp to the axis. Its diameter is 23 Ȧ. It has a pitch of 28.2 Ȧ per turn of the helix.
    2. B-DNA: B-DNA, also shown as B form DNA, is a right-handed double helix structure with a mean propeller twist of +16°. It has 34.3° rotation per (bp) and ten mean bp per turn. It has a -1.2° inclination of bp to the axis. Its diameter is 20 Ȧ. It has a pitch of 33.2 Ȧ per turn of the helix.
    3.  Z-DNA: Z-DNA or Z form DNA is a left-handed double helix structure form with a mean propeller twist of 0°. It has 30° rotation per (bp), and 12 mean bp per turn. It has a -9° inclination of bp to the axis. Its diameter is 18 Ȧ. Its double helix spirals to the left in a zig-zag pattern. It has a pitch of 45.6 Ȧ per turn of the helix.

    There are several kinds of RNA, the most commonly studied in a human body are :

    • Messenger RNA [mRNA]: The Messenger RNA consists of the genetic blueprint to make protein. Its primary function is transmitting the genetic material in the ribosomes and handing the instructions about the kind of proteins needed by the body’s cells. The mRNA plays a crucial role in the transcription process or during protein synthesis
    • Transfer RNA [tRNA]: The tRNA translates mRNA into proteins and is accountable for carrying the amino acids needed by the body. It is found at the endpoints of each of the amino acids and has a cloverleaf structure
    • Ribosomal RNA [rRNA]: Ribosomal RNA forms ribosomes and plays a significant role in protein synthesis. They are found in all organisms and serve to convert the instructions found from mRNA

    Conclusion

    In this article, we have discussed the structure of DNA and RNA, their definition, and their classification. In addition, we discussed how the structure of DNA and RNA is formed and what role plays in our body.  Further, different types of RNA and DNA that are taken as important part of the study and how are they important in human body. Once you will go in-depth through all topics discussed in the article, you will get a better more confidence over the topic.

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