Biology · Biomolecules · NEET
| Components | Adenosine: base + sugar | Adenylic acid: base + sugar + phosphate |
| Category | Nucleoside | Nucleotide |
| Phosphate group | Absent | Present (esterified to sugar) |
| Acidic nature | Not acidic | Acidic (from phosphate) |
| Other name | Adenosine | AMP (adenosine monophosphate) |
Adenosine is a NUCLEOSIDE. It is the nitrogen base adenine joined to a sugar, with NO phosphate. Because it has no phosphate, it cannot be a nucleotide. Add one phosphate and it becomes adenylic acid, which is the nucleotide.
Adenylic acid is the NUCLEOTIDE of adenine. It is adenine + sugar + phosphate. It is also called AMP (adenosine monophosphate). The phosphate group makes it acidic, which is why NCERT names it adenylic ACID.
Adenine alone is just the nitrogen base (a purine). Add a sugar and you get adenosine (nucleoside). Add a phosphate to that and you get adenylic acid (nucleotide). So the ladder is: base to nucleoside to nucleotide.
The extra phosphate group in adenylic acid can release H+ ions, so it behaves as an acid. Adenosine has no phosphate, so it is not acidic. This naming clue helps NEET students: -ylic acid means phosphate is present, so it is a nucleotide.
Follow the same rule. Guanine gives guanosine (nucleoside) and guanylic acid (nucleotide). Cytosine gives cytidine and cytidylic acid. Uracil gives uridine and uridylic acid. Thymine gives thymidine and thymidylic acid. Base to nucleoside to nucleotide.
Match List-I with List-II. List-I: A. Adenosine; B. Adenylic acid; C. Adenine; D. Alanine. List-II: I. Nitrogen base; II. Nucleotide; III. Nucleoside; IV. Amino acid. Choose the option with all correct matches.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
No. Adenosine is a nucleoSide (adenine + sugar, no phosphate). The nucleotide of adenine is adenylic acid (AMP).
Adenylic acid is also called AMP, or adenosine monophosphate. It is the nucleotide of adenine.
No. Adenosine has only a nitrogen base and a sugar. Adding a phosphate turns it into adenylic acid, a nucleotide.
The phosphate group is joined to the sugar by an ester bond (phosphoester). NCERT says the phosphate is 'esterified to the sugar' to form the nucleotide.
Base + sugar = nucleoside (name ends in -osine/-idine). Base + sugar + phosphate = nucleotide (name ends in -ylic acid). Adenosine to adenylic acid is the classic example.
