Most-Tested Traps in Biomolecules

Trap 1: "Fructose is non-reducing because it's a ketose"

• WRONG. Fructose IS a reducing sugar.
• Reason: Alpha-hydroxy ketone → enolises under alkaline test conditions → gives reducing species.

Trap 2: "Denaturation breaks all protein bonds"

• WRONG. Denaturation does NOT break peptide bonds (primary structure).
• Correct: Denaturation breaks H-bonds, disulfide bonds, hydrophobic, ionic interactions.

Trap 3: "Both A-T and G-C have 2 H-bonds"

• WRONG. A-T = 2 H-bonds; G-C = 3 H-bonds.
• Consequence: Higher G-C% → higher Tm.

Trap 4: "Sucrose has free -OH so it's reducing"

• WRONG. Having -OH groups is not the criterion for reducing ability.
• Sucrose has many -OH groups but NO free anomeric carbon.

Trap 5: "Vitamin K is water-soluble"

• WRONG. K is fat-soluble (ADEK).

Trap 6: "Cellulose can be digested if cooked"

• WRONG. Cooking does not convert beta-glycosidic bonds to alpha. Humans permanently lack cellulase.

Trap 7: "Amylose and amylopectin have the same linkage"

• WRONG. Amylose: alpha-1,4 only (linear). Amylopectin: alpha-1,4 + alpha-1,6 (branched).

Trap 8: "rRNA is least abundant RNA"

• WRONG. rRNA is the MOST abundant RNA (~80% of total cellular RNA).

Trap 9: "Glycine has a chiral centre"

• WRONG. Glycine (R=H) has two identical H atoms on alpha-C → achiral.

Trap 10: "The peptide bond is a single C-N bond"

• WRONG. The peptide bond has partial double-bond character (~40%) due to resonance → restricted rotation → planar unit.