Chapter 9 — Biomolecules

Biomolecules are organic compounds found in living organisms including proteins, lipids, carbohydrates, and nucleic acids, which together form the chemical foundation of all living systems.

Chapter 9 explores the chemical composition of living organisms and the major biomolecules that distinguish life from non-living matter. Through elemental analysis, scientists discovered that living tissues have higher relative abundance of carbon, hydrogen, and oxygen compared to earth's crust. The chapter covers four major classes of biomacromolecules: proteins (polymers of 20 amino acids linked by peptide bonds), polysaccharides (long chains of sugars like cellulose, starch, and glycogen), nucleic acids (DNA and RNA containing nitrogenous bases), and lipids. It also explains primary metabolites found in all organisms and secondary metabolites unique to plants and microbes, along with enzyme structure and function.

1. 01Living organisms contain water (70-90%), proteins (10-15%), carbohydrates (3%), and lipids (2%) with nucleic acids making up 5-7% of cellular mass
2. 02Biomolecules are classified into micromolecules (<1000 Da) found in acid-soluble fractions and macromolecules (>10,000 Da) including proteins, nucleic acids, and polysaccharides
3. 03Amino acids are the building blocks of proteins with 20 types occurring in nature, each containing amino, carboxyl, and variable R groups
4. 04Proteins exhibit four levels of structure: primary (amino acid sequence), secondary (helix and pleated sheet), tertiary (3D folding), and quaternary (multiple subunit assembly)
5. 05Enzymes are protein catalysts that lower activation energy and accelerate biochemical reactions by forming substrate-enzyme complexes at their active sites
6. 06Nucleic acids (DNA and RNA) contain nitrogenous bases (adenine, guanine, cytosine, thymine, uracil), a monosaccharide sugar, and phosphoric acid components