Adenosine monophosphate is a
A) Nucleoside of DNA
B) Nucleotide of DNA
C) Nucleoside of RNA
D) Nucleotide of RNA

Hint: Adenosine monophosphate (AMP) is one of the components of RNA and the organic component of the energy-carrying molecule ATP. It has a phosphate group, the sugar ribose and the nucleobase adenine.

Complete Answer:
- In some metabolic processes, AMP combines with inorganic phosphate to form ADP (adenosine diphosphate) and then ATP.
- The breaking of phosphate bonds in ATP releases a lot of energy which are utilized in driving chemical reactions or contracting muscle fibres. This is done when 5’ adenosine monophosphate-activated protein kinase, or AMPK, utilizes AMP for homeostatic energy processed at time of high cellular energy expenditure, like exercise.
- Since ATP cleavage and subsequent phosphorylation reactions are utilized as a source of energy in the processes occurring throughout the body, ATP production is vital to create additional energy for those mammalian cells.
- AMPK is activated by the decreasing levels of ATP, accompanied with the increasing levels of ADP and AMP. Some studies have suggested that AMP is an allosteric regulator and activates AMPK.
- Other studies showed that, not just AMP, but the high ratio of AMP: ATP levels in the cells activates AMPK. For example, it was found that in species of C. elegans and Drosophila melanogaster, the AMPK was activated by AMP whereas in species of yeast and plants, the kinases were not allosterically activated by AMP.
- AMP, also known as 5’-adenylic acid, is present in all known forms of life and is a nucleotide. The nitrogenous bases are purines and pyrimidines. Phosphoric acid is the phosphate present in it and the nucleotide is formed by the union of a phosphate group with a nucleoside.

Hence, the correct option is option D, ‘nucleotide of RNA’.

Note: AMP can also exist as Cyclic AMP which is also a nucleotide involved in regulating various aspects of cellular metabolism like the breakdown of glycogen. cAMP has an important role in intracellular signaling.