Question

What kind of covalent bonds join monomeric units in polysaccharides?

• A. Glucose bond
• B. Peptide bond
• C. Phosphodiester bond
• D. Glycosidic bond

Hint:

Biopolymer Covalent Linkages:
Polysaccharides $\rightarrow$ Glycosidic bond.
Proteins $\rightarrow$ Peptide bond.
Nucleic Acids $\rightarrow$ Phosphodiester bond.
Lipids $\rightarrow$ Ester bond.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Biomolecular polymerization links monosaccharides via covalent acetal/ketal $O$-glycosidic linkages.
Key Formula or Approach:
\[ \text{Monosaccharide-OH} + \text{HO-Monosaccharide} \xrightarrow{-\text{H}_2\text{O}} \text{Monosaccharide-O-Monosaccharide } (O\text{-Glycosidic Bond)} \]

Step 2: Detailed Explanation:
Polymer covalent bonding classification:
1. Glycosidic Bond ($O$-Glycosidic Bond): Covalent ether linkage formed between the hemiacetal/hemiketal anomeric carbon hydroxyl group of one sugar and an alcohol hydroxyl group of another sugar, joining monosaccharide units in glycogen, starch, and cellulose.
2. Peptide Bond: Links amino acids in proteins.
3. Phosphodiester Bond: Links nucleotides in nucleic acids.
4. Ester Bond: Links fatty acids to glycerol in lipids.

Step 3: Final Answer:
Hence, covalent bonds joining polysaccharides are Glycosidic bonds, matching option (D).