THE MOLECULAR BASIS OF INHERITANCE
STRUCTURE OF NUCLEIC ACIDS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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5’ end has a hydroxyl and 3’ end has a phosphate
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5’ end has a phosphate and 3’ end has a hydroxyl
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5’ end has an amino group and 3’ end has a carboxyl group
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5’ end has a carboxyl group and 3’ end has a amino group
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Detailed explanation-1: -3’ end/5’ end: A nucleic acid strand is inherently directional, and the “5 prime end” has a free hydroxyl (or phosphate) on a 5’ carbon and the “3 prime end” has a free hydroxyl (or phosphate) on a 3’ carbon (carbon atoms in the sugar ring are numbered from 1’ to 5’).
Detailed explanation-2: -DNA is always synthesized in the 5’-to-3’ direction, meaning that nucleotides are added only to the 3’ end of the growing strand. As shown in Figure 2, the 5’-phosphate group of the new nucleotide binds to the 3’-OH group of the last nucleotide of the growing strand.
Detailed explanation-3: -Each end of DNA molecule has a number. One end is referred to as 5’ (five prime) and the other end is referred to as 3’ (three prime). The 5’ and 3’ designations refer to the number of carbon atom in a deoxyribose sugar molecule to which a phosphate group bonds.
Detailed explanation-4: -DNA and RNA are composed of nucleotides that are linked to one another in a chain by chemical bonds, called ester bonds, between the sugar base of one nucleotide and the phosphate group of the adjacent nucleotide. The sugar is the 3’ end, and the phosphate is the 5’ end of each nucleiotide.
Detailed explanation-5: -5’ end has a hydroxyl or phosphate group on the 5’ carbon of its terminal sugar; the 3’ end usually has a hydroxyl group on the 3’ carbon of its terminal sugar. This structure gives a distinct polarity to the DNA strand.