1.1.4Unit 1: Lifestyle, Transport, Genes and Health
Condensation and Hydrolysis — IAL Edexcel Linear Revision Notes & Topical Questions
5 min read 4 parts Lesson 11 of 29 Unit quiz
Curriculum Equation Key قوانين الرقم الهيدروجيني والاتزان الأيوني - pH & Acid-Base Equilibrium FormulasFast Exam Solution
pH = -log[H⁺] | pOH = -log[OH⁻] | pH + pOH = 14 | [H⁺][OH⁻] = 10⁻¹⁴
Word Equation & Conditions: الرقم الهيدروجيني = -لوغاريتم تركيز أيون الهيدروجين | pH + pOH = 14
Location & Specifications: الاتزان الأيوني، كيمياء 3 ثانوي، التحصيلي، و AP Chemistry.
Part 1 of 4Condensation Reactions
The same two reaction types, condensation and hydrolysis, operate across many biological molecules.
Definition
- Definition A condensation reaction joins two molecules together by forming a covalent bond and releasing a molecule of water.
Glycosidic bond
- Glycosidic bond Two monosaccharides join when the –OH group on one reacts with the –OH on the other, forming a C–O–C link.
Bond numbering
- Bond numbering If carbon 1 of one sugar joins to carbon 4 of the other, the bond is a 1,4 glycosidic bond;
- carbon 1 to carbon 6 gives a 1,6 bond.
Polymer building
- Polymer building Repeating the reaction many times forms polysaccharides, with one water molecule released for each bond made.
Part 2 of 4Hydrolysis Reactions
1
Hydrolysis is the reverse of condensation: a molecule of water is added across a bond, which splits it into two smaller molecules.
2
A glycosidic bond in a disaccharide or polysaccharide is hydrolysed to release monosaccharides, and enzymes such as amylase speed up the reaction.
3
The –H from the water attaches to one product and the –OH to the other, so water is a reactant, not a product.
4
Digestion in the gut uses hydrolysis to break large insoluble molecules into small soluble ones that can be absorbed.
5
The stores of starch and glycogen in cells are also hydrolysed to release glucose for respiration when it is needed.
| Reaction | Water | Effect on bond |
|---|---|---|
| Condensation | Released | Bond formed |
| Hydrolysis | Used | Bond broken |
Part 3 of 4Examples Across Biochemistry
Examples Across Biochemistry
Disaccharides
- Disaccharides Two glucose molecules condense to form maltose: C₆H₁₂O₆ + C₆H₁₂O₆ → C₁₂H₂₂O₁₁ + H₂O.
Triglycerides
- Triglycerides Glycerol and fatty acids are linked by ester bonds in condensation reactions that release water.
Proteins
- Proteins Amino acids are joined by peptide bonds by condensation and split again by hydrolysis during protein digestion.
Nucleic acids
- Nucleic acids Nucleotides join through phosphodiester bonds in condensation reactions when DNA or RNA is made.
Part 4 of 4Exam Checklist & Tips
1.1.4 – Key Points for the Exam
- Condensation reaction A reaction that joins two molecules together with the loss of a molecule of water.
- Hydrolysis A reaction that breaks a bond by adding a molecule of water.
- Glycosidic bond The covalent bond between two monosaccharides.
- Polymer A large molecule made from many repeating monomer units.
Common Mistakes
- Writing that water is used up in a condensation reaction; it is released.
- Saying that hydrolysis forms glycosidic bonds; it breaks them.
- Forgetting to balance the equation, since maltose is C₁₂H₂₂O₁₁ and not C₁₂H₂₄O₁₂.
- Describing the products of hydrolysis as polymers instead of smaller monomers.
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