Condensation Reactions
Definition
Condensation
Condensation is a reaction where two molecules combine, releasing water.
- It is enzyme-catalyzed, requires energy input, and typically occurs inside cells.
- The removal of H₂O allows the formation of a covalent bond between the reacting functional groups.
- These reactions are reversible via hydrolysis, which breaks the polymer back into monomers by adding water.
- Think of condensation reactions as building a brick wall (polymer) from individual bricks (monomers).
- The mortar that holds them together is formed by removing water from the bricks!
Key Macromolecules Formed by Condensation
- The main types of biological macromolecules produced through condensation are:
- Polysaccharides
- Polypeptides (proteins)
- Nucleic acids (DNA and RNA)
- Each type of macromolecule has distinct monomers, bond types, and biological functions.
1. Polysaccharides (Carbohydrates)
- Monomer
- Monosaccharides single sugar units with the general formula (CH₂O)n.
- Examples: α-glucose, β-glucose, galactose, fructose
- Reaction
- Glycosidic bond formation occurs between hydroxyl (-OH) groups on two monosaccharides.
- Enzyme example: maltase catalyzes maltose formation
- By-product: one molecule of H₂O per glycosidic bond
| Polysaccharide | Monomer | Bondy Type | Function | Structure |
|---|---|---|---|---|
| Starch | α-glucose | α(1→4) and α(1→6) | Energy storage in plants | Amylose (unbranched), Amylopectin (branched) |
| Glycogen | α-glucose | α(1→4), α(1→6) | Energy storage in animals (liver, muscle) | Highly branched |
| Cellulose | β-glucose | β(1→4) | Structural component in plant cell walls | Straight chains; form microfibrils |
2. Polypeptides (Proteins)
- Monomer:
- Amino acids contain a central carbon (C) bonded to:
- An amino group (-NH₂)
- A carboxyl group (-COOH)
- A hydrogen atom
