Chapter 10, Problem 2STP

Summary Introduction

Introduction :

Adenosine triphosphate (ATP) is a nucleotide. It is formed of nitrogenous base, adenine and a pentose sugar, ribose sugar and three phosphate groups (triphosphate). Adenosine triphosphate stores energy in the terminal phosphate bond which is depicted in between label 1 and 2.

Answer to Problem 2STP

Correct answer :

The correct answer is option (A) 1and 2.

Explanation of Solution

Explanation/justification for the correct answer :

Option (A) 1 and 2. When the terminal phosphate bond between 1 and 2 in the given illustration is removed by hydrolyzing ATP in the presence of ATPase enzyme, as a result ATP is converted to adenosine diphosphate (ADP), inorganic phosphate (pi) and energy. Thus, on removal of phosphate group from ATP, ADP is formed and releases energy for use in the organism. Thus, the correct answer is option (A).

The explanation for the incorrect answer :

Option (B) 2 and 3. Label 2 is a terminal phosphate and label 3 is a ribose sugar joined by an ester bond which does not release energy. Thus, this is an incorrect option.

Option (C) 2 and 4. Label 2 is a terminal phosphate and label 4 a nitrogenous base. These two groups not joined by any bond. Thus, this is an incorrect option.

Option (D) 3 and 4. Label 3 is a ribose sugar and label 4 is a nitrogenous base adenine. These two are joined by a glycosidic bond which does not release energy. Thus, this is an incorrect option.