Overview
This lecture explains the biochemical basis of life, focusing on biological molecules, the concepts of monomers and polymers, and condensation and hydrolysis reactions.
Biochemical Basis of Life
- All living organisms, despite their diversity, share a common biochemical basis centered on carbon chemistry.
- The study of life’s molecules is called biochemistry.
- Carbon’s ability to form four bonds allows it to create complex molecules acting as the backbone of organic compounds.
Major Biological Molecules
- Four main types of biological molecules: carbohydrates (sugars), lipids (fats), proteins, and nucleic acids (e.g., DNA).
- Carbohydrates: composed of carbon, hydrogen, and oxygen.
- Lipids: also contain carbon, hydrogen, and oxygen but differ structurally from carbohydrates.
- Proteins: contain carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur.
- Nucleic acids: contain carbon, hydrogen, oxygen, nitrogen, and phosphorus.
- These molecules are called macromolecules due to their large size.
Monomers and Polymers
- Monomers are single building blocks that join to form polymers, which are long chains of repeating units.
- Carbohydrates: monomer = monosaccharide, polymer = polysaccharide.
- Proteins: monomer = amino acid, polymer = polypeptide.
- Nucleic acids: monomer = nucleotide, polymer = polynucleotide.
- Lipids are not true polymers; they are formed from glycerol and fatty acids but lack repeating monomers.
Condensation and Hydrolysis Reactions
- Condensation reactions join monomers, releasing water and forming bonds; essential for building polymers.
- Hydrolysis reactions break down polymers into monomers, requiring water to break the bonds.
- Condensation: monomers combine → polymer + water is formed.
- Hydrolysis: polymer + water → monomers are released.
- These reactions occur in all cells and are examples of metabolic reactions.
Key Terms & Definitions
- Biochemistry — the study of molecules that form the basis of life.
- Organic molecule — a molecule containing carbon atoms bonded together.
- Macromolecule — a large molecule comprised of many atoms, such as proteins or nucleic acids.
- Monomer — a small, basic molecular unit that can join others to form polymers.
- Polymer — a large molecule made up of repeating monomer units.
- Condensation reaction — a chemical reaction where two molecules join, forming a bond and releasing water.
- Hydrolysis reaction — a reaction that breaks a bond in a molecule using water.
Action Items / Next Steps
- Review the structure and elemental composition of carbohydrates, lipids, proteins, and nucleic acids.
- Practice identifying monomers and polymers for each biological molecule type.
- Memorize the definitions and differences between condensation and hydrolysis reactions.