AP BIOLOGY

THE MOLECULAR BASIS OF INHERITANCE

STRUCTURE OF NUCLEIC ACIDS

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
DNA and RNA are composed of several nucleotide monomers bonded together. Where does this bond occur between two nucleotides?
A
Between the sugar and the phosphate
B
Between adjacent nitrogenous bases
C
Between the sugar and the neighboring nitrogenous base
D
Between the phosphate and the neighboring nitrogenous base
Explanation: 

Detailed explanation-1: -The phosphate group of one nucleotide bonds covalently with the sugar molecule of the next nucleotide, and so on, forming a long polymer of nucleotide monomers. The sugar–phosphate groups line up in a “backbone” for each single strand of DNA, and the nucleotide bases stick out from this backbone.

Detailed explanation-2: -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.

Detailed explanation-3: -In both DNA and RNA, the phosphodiester bond is the linkage between 5’ carbon atom of one ribose sugar molecule and 3’ carbon atom of another ribose molecule in RNA and deoxyribose in DNA. A phosphodiesterase enzyme is responsible for the hydrolysis of phosphodiester bonds.

Detailed explanation-4: -Covalent bonds occur within each linear strand and strongly bond the bases, sugars, and phosphate groups (both within each component and between components). Hydrogen bonds occur between the two strands and involve a base from one strand with a base from the second in complementary pairing.

Detailed explanation-5: -The monomers of the nucleic acid are linked by a link known as N-glycosidic linkage or glycosidic linkage. A glycosidic bond or glycosidic linkage is a type of covalent bond that joins a carbohydrate molecule to another group, which may or may not be another carbohydrate.

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