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प्रश्न
Describe the structure of RNA polynucleotide chain having four different types of nucleotides.
उत्तर
A RNA nucleotide has three main components − a nitrogenous base, a ribose sugar and a phosphate group.
• The ribose sugar and the phosphates form the backbone of a polynucleotide chain with nitrogenous bases linked to sugar moiety and projecting from the backbone.
• Two types of nitrogenous bases are present i.e. Purines (Adenine and Guanine) and Pyrimidines (Cytosine and Uracil).
• A nitrogenous base is linked to the ribose sugar through N-glycosidic linkages to form a nucleoside (like adenosine, guanosine or cytidine and uridine).
• A phosphate group is linked to 5'-OH of a nucleoside through phosphoester linkage to form a corresponding nucleotide.
• Every nucleotide residue has an additional −OH group present at 2' -position in the ribose.
• Many nucleotides are linked through 3'-5' phosphodiester linkages to each other to form the polynucleotide chain.
• The end of the chain which has a free phosphate moiety at 5'-end of ribose sugar is referred to as 5’-end and the other end of the chain having a free 3'-OH group at the ribose sugar is referred to as 3' -end of the polynucleotide chain.
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संबंधित प्रश्न
Write the dual purpose served by Deoxyribonucleoside triphosphates in the polymerisation.
Two important RNA processing events lead to specialized end sequences in most human mRNAs: ______(i)______ at the 5’ end, and ______(ii)______ at the 3’ end. At the 5’end the most distinctive specialized end nucleotide, ______(iii)______ is added and a sequence of about 200 ______(iv)______ is added to the 3’ end.
Write a 6-nucleotide long palindromic sequence on a double stranded DNA, which was reverse transcribed by the following nucleotide sequence on a retroviral RNA.
3’-GUA--- 5’
