The length of one turn of the helix in a $B$- form DNA is approximately-
- 0.34 nm
- 20 nm
- 2 nm
- 3.4 nm
The Correct Option is D
Solution and Explanation
$1 nm =10^{-9} m $
$1 \,Å=10^{-10} m$
$34 \,Å=34 \times 10^{-10} m $
or $=3.4 \times 10^{-9} m $
So, $=3.4 \,nm$.
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Concepts Used:
Structure of DNA and RNA
DNA Structure:
Human DNA is unique and is made up of 3 billion base pairs. However, 99% of them are the same in all humans. The sequence of these bases determines what information needs to be coded that is necessary for the organism's growth and development. During the process of transcription (when DNA is replicated), a product is formed known as RNA (Ribonucleic Acid). This RNA is responsible for translating genetic information from DNA to protein followed by reading through ribosomes.
Read More: Structure of DNA
RNA Structure:
The ribonucleic acid has all the components same to that of the DNA with only 2 main differences within it. RNA has the same nitrogen bases called the adenine, Guanine, Cytosine as that of the DNA except for the Thymine which is replaced by the uracil. Adenine and uracil are considered as the major building blocks of RNA and both of them form base-pair with the help of 2 hydrogen bonds.
RNA resembles a hairpin structure and like the nucleotides in DNA, nucleotides are formed in this ribonucleic material(RNA). Nucleosides are nothing but the phosphate groups which sometimes also helps in the production of nucleotides in the DNA.
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