Overview
This lecture reviews the essential roles of carbon and phosphorus in life, explains energy transfer via ATP, and focuses on dehydration synthesis and hydrolysis in biological molecules.
Elements Essential for Life
- Carbon is crucial because it forms the backbone of organic molecules like proteins and DNA.
- Phosphorus is essential for cellular energy transfer as a part of ATP (adenosine triphosphate).
Biological Energy and Reactions
- ATP is the main energy molecule used in both breaking down (catabolic) and building up (anabolic) biological molecules.
- Catabolic reactions break large molecules (lipids, carbohydrates, proteins) into smaller ones, releasing energy stored in ATP.
- Anabolic reactions build larger molecules from smaller ones, requiring energy input and breaking down ATP.
Dehydration Synthesis (Anabolic Process)
- Dehydration synthesis forms covalent bonds between molecules by removing water (H₂O).
- Monomers join to form dimers and then polymers, with each join releasing one water molecule.
- Examples include formation of starch and maltose in plants, glycogen and lactose in animals, proteins from amino acids, and lipids from fatty acids.
Hydrolysis (Catabolic Process)
- Hydrolysis breaks bonds in polymers by adding a water molecule, creating smaller molecules.
- Cellulose is broken down by hydrolysis in animals like cows to produce glucose for energy.
- Humans use hydrolysis to digest food, for example, breaking sucrose into glucose and fructose.
Key Terms & Definitions
- ATP (Adenosine Triphosphate) — the cell’s main energy carrier molecule.
- Catabolic Reaction — breaks down larger molecules into smaller ones, releasing energy.
- Anabolic Reaction — builds larger molecules from smaller ones, requiring energy.
- Dehydration Synthesis — anabolic reaction where bonds form by removing water.
- Hydrolysis — catabolic reaction breaking bonds by adding water.
- Monomer — a small molecule that can join with others to form polymers.
- Polymer — a large molecule made up of repeating monomer units.
Action Items / Next Steps
- Review additional examples of dehydration synthesis and hydrolysis in your textbook.
- Practice identifying catabolic and anabolic reactions in metabolic pathways.