Step 1: What is Streptomycin?
Streptomycin is an aminoglycoside antibiotic produced by Streptomyces griseus. It was the first antibiotic effective against tuberculosis. Its complex structure consists of three sugar-like units joined together.
Step 2: The three structural components.
Streptomycin is made of three parts: (a) Streptidine - a cyclohexane derivative with two guanidino groups, (b) Streptose - a branched-chain sugar (L-streptose), (c) N-methyl-L-glucosamine - an amino sugar with a methyl group on the nitrogen.
Step 3: Why option 4 is correct.
All three components must be named together to describe the complete structure. Option 4 lists all three: "Streptidine, streptose and N-methyl-L-glucosamine."
Step 4: Why other options are incomplete.
Option 1 misses N-methyl-L-glucosamine. Option 2 misses streptose. Option 3 misses streptidine. None of these partial answers correctly describes the full molecule.
Step 5: Memory tip.
Remember: Streptomycin = Streptidine + Streptobiose. Streptobiose itself = Streptose + N-methyl-L-glucosamine. So the complete molecule has three named parts.
Answer: Option (4) — Streptidine, streptose and N-methyl-L-glucosamine