Biomolecules

Carbohydrates

Polyhydroxy aldehydes or ketones. Reducing sugars have free aldehyde/keto group (glucose, maltose); sucrose is non-reducing (glycosidic link between anomeric carbons).

Glucose: cyclic hemiacetal (α and β anomers), pyranose in solution. Fructose favours furanose. Starch (amylose/amylopectin) vs cellulose (β-1,4 link — humans do not digest).

Tests: Molisch (general), Fehling’s/Benedict’s for reducing sugars, iodine for starch.

Proteins and enzymes

Amino acids: zwitterion at neutral pH; isoelectric point. Peptide bond joins –NH₂ and –COOH with loss of water. Primary → secondary (H-bond, α-helix, β-sheet) → tertiary → quaternary.

Denaturation unfolds protein without breaking peptide bonds (heat, pH, heavy metals). Enzymes are biological catalysts; lock-and-key is a simple model; induced fit is closer.

Vitamins and nucleic acids

Vitamins: fat-soluble (A, D, E, K) vs water-soluble (B group, C). Deficiency diseases (night blindness, scurvy, rickets — match the pair your table lists).

DNA: double helix, A–T two H-bonds, G–C three. RNA: uracil instead of thymine, usually single stranded. Nucleotide = base + sugar + phosphate. Replication and transcription are biology overlap — chemistry wants structure and hydrogen bonding picture.