2.4 Condensation and Hydrolysis

Introduction

Biological molecules like carbohydrates, proteins, lipids, and nucleic acids are mostly polymers. A polymer is a large molecule made of many repeating smaller units called monomers. The process by which monomers are joined together to form polymers is called condensation, and the process by which polymers are broken down into monomers is called hydrolysis. These two processes are essential for the making and breaking of all biological macromolecules.

Definition

Macromolecule/Polymer: A compound which has high molecular weight and is made from many repeating units is known as a macromolecule or polymer.

Monomer: The individual units of a polymer are micromolecules and are called monomers.

Condensation: The process by which two monomers join together with the removal of a water molecule to form a bond is called condensation. It is also called dehydration synthesis because water is removed (dehydration) and a bond is made (synthesis).

Hydrolysis: The process by which a polymer is broken down into its monomers by the addition of water is called hydrolysis. It is essentially the reverse of condensation.

• Condensation = joining monomers by removing water.
• Hydrolysis = breaking polymers by adding water.

Core Concept

• The interconversions of monomers and polymers are carried out by condensation and hydrolysis.
• Condensation builds polymers (anabolism).
• Hydrolysis breaks polymers (catabolism).
• Both processes require specific enzymes.
• Both processes are essential for life.

Detailed Explanation

Condensation (Dehydration Synthesis)

Definition: During condensation, when two monomers (e.g., Alpha-Glucose) join, a hydroxyl (-OH) group is removed from one monomer (first Alpha-Glucose) and a hydrogen (-H) is removed from the other (second Alpha-Glucose) to release water. As a result, a bond is formed between the monomers.

In simple words: Condensation is the process of joining two molecules together by removing a water molecule.

Steps in Condensation:

• Two monomers come close together.
• A hydroxyl group (-OH) is removed from one monomer.
• A hydrogen atom (-H) is removed from the other monomer.
• These combine to form water (H₂O).
• A bond is formed between the two monomers.

Example: Formation of Maltose from Two Glucose Molecules

• Alpha-Glucose + Alpha-Glucose → Maltose + Water
• The product (Maltose) of such a reaction is called a dimer.
• A dimer is a molecule made of two monomers.

Example: Formation of Amylose from Many Glucose Molecules

• If the same reaction is repeated several times, the resulting molecule will be a polymer.
• For example, many Alpha-Glucose molecules condense to form Amylose, and many water molecules are released.

Number of Water Molecules Released:

• The number of water molecules released during a condensation reaction depends upon the number of bonds formed.
• Example: 19 water molecules will be released when 20 monomers are condensed to form a polymer.
• Formula: If n monomers join to form a polymer, n - 1 water molecules are released.

Conditions for Condensation:

• The proper enzyme is present.
• The monomers are in an activated energy-rich form.

Other Names for Condensation:

- Dehydration synthesis – Because water is removed (dehydration) and a bond is made (synthesis).

Hydrolysis

Definition: Hydrolysis is essentially the reverse of condensation, i.e., the breakdown of a dimer or polymer into its monomers by the addition of water.

In simple words: Hydrolysis is the process of breaking a polymer into its monomers by adding water.

Steps in Hydrolysis:

• A water molecule (H₂O) is added.
• An (-OH) group from water is attached to one monomer.
• A (-H) is attached to the other monomer.
• The bond between the monomers is broken.
• The monomers are released.

Example: Breakdown of Maltose into Two Glucose Molecules

• Maltose + Water → Alpha-Glucose + Alpha-Glucose
• The bond between the two glucose molecules is broken by the addition of water.

Example: Breakdown of Amylose into Many Glucose Molecules

• Amylose + Water → Many Alpha-Glucose Molecules
• The bonds between the glucose molecules are broken by the addition of water.
• This reaction is catalysed by the enzyme amylase.

Enzymes Involved in Hydrolysis:

Comparison of Condensation and Hydrolysis

Intermediate Level

Condensation in Detail

• During condensation, a covalent bond is formed between the two monomers.
• The type of bond depends on the type of monomers:
• Glycosidic bond – Between sugars (carbohydrates)
• Peptide bond – Between amino acids (proteins)
• Ester bond – Between glycerol and fatty acids (lipids)
• Phosphodiester bond – Between nucleotides (nucleic acids)

• Water is released as a byproduct.
• The number of water molecules released depends on the number of bonds formed.
• Formula: For n monomers, n - 1 water molecules are released.

• Condensation requires energy.
• The monomers must be in an activated energy-rich form.
• This energy is often provided by ATP.

• Specific enzymes are required for condensation reactions.
• Examples:
• Glycosyltransferases – Form glycosidic bonds
• Peptidyl transferase – Forms peptide bonds
• DNA polymerase – Forms phosphodiester bonds

Hydrolysis in Detail

• During hydrolysis, a covalent bond is broken by the addition of water.
• The water molecule is split:
• (-OH) goes to one monomer.
• (-H) goes to the other monomer.

• Hydrolysis releases energy.
• This energy is used by the cell for various activities.

• Specific enzymes are required for hydrolysis.
• Examples:
• Amylase – Breaks down starch
• Protease – Breaks down proteins
• Lipase – Breaks down lipids
• Nuclease – Breaks down nucleic acids

Biological Importance

• Builds all biological macromolecules.
• Stores energy in chemical bonds.
• Allows the cell to grow and repair.

• Breaks down food molecules for energy.
• Releases monomers for building new molecules.
• Allows the cell to recycle materials.

Examples in the Body:

Important Points

• 1. A compound which has high molecular weight and is made from many repeating units is known as a macromolecule or polymer.
• 2. The individual units of a polymer are micromolecules and are called monomers.
• 3. The interconversions of these molecules are carried out by condensation and hydrolysis.
• 4. During condensation, when two monomers (e.g., Alpha-Glucose) join:
• - A hydroxyl (-OH) group is removed from one monomer (first Alpha-Glucose).
• - A hydrogen (-H) is removed from the other (second Alpha-Glucose).
• - Water is released.
• - A bond is formed between the monomers.
• - The product (Maltose) of such a reaction is called a dimer.
• 5. If the same reaction is repeated several times, the resulting molecule will be a polymer.
• - For example, many Alpha-Glucose molecules condense to form Amylose, and many water molecules are released.
• 6. The number of water molecules released during a condensation reaction depends upon the number of bonds formed.
• - Example: 19 water molecules will be released when 20 monomers are condensed to form a polymer.
• 7. Condensation is also called dehydration synthesis because water is removed (dehydration) and a bond is made (synthesis).
• 8. Condensation does not take place unless:
• - The proper enzyme is present.
• - The monomers are in an activated energy-rich form.
• 9. Hydrolysis is essentially the reverse of condensation, i.e., the breakdown of a dimer or polymer into its monomers by the addition of water.
• 10. During hydrolysis:
• - An (-OH) group from water is attached to one monomer.
• - A (-H) is attached to the other monomer.
• - For example, breakdown of Amylose in the presence of amylase enzyme and splitting of water molecule.

Remember

• - Macromolecule/Polymer = large molecule made of repeating units
• - Monomer = individual unit of a polymer
• - Condensation = joining monomers; water removed; bond formed
• - Hydrolysis = breaking polymers; water added; bond broken
• - Condensation = dehydration synthesis
• - Hydrolysis = reverse of condensation
• - Water molecules released = n - 1 (for n monomers)
• - Enzymes required for both processes
• - Condensation = anabolic (building)
• - Hydrolysis = catabolic (breaking)
• - Examples:
• - Condensation: Glucose + Glucose → Maltose + Water
• - Hydrolysis: Maltose + Water → Glucose + Glucose

Common Mistakes

• 1. Confusing condensation and hydrolysis – Condensation builds (water removed); Hydrolysis breaks (water added).
• 2. Thinking water is added in condensation – Water is removed in condensation.
• 3. Thinking water is removed in hydrolysis – Water is added in hydrolysis.
• 4. Forgetting that condensation is also called dehydration synthesis – Dehydration = water removed; Synthesis = bond formed.
• 5. Thinking condensation does not require energy – Condensation requires energy.
• 6. Thinking hydrolysis does not require enzymes – Hydrolysis requires specific enzymes.
• 7. Confusing the number of water molecules released – For n monomers, n - 1 water molecules are released.
• 8. Thinking all bonds are the same – Different monomers form different bonds:
• - Glycosidic (sugars)
• - Peptide (amino acids)
• - Ester (glycerol + fatty acids)
• - Phosphodiester (nucleotides)
• 9. Thinking hydrolysis only occurs in digestion – Hydrolysis also occurs in the cell to break down molecules for recycling.
• 10. Thinking condensation only occurs in synthesis – Condensation also occurs in the cell to store energy in chemical bonds.
• 11. Confusing anabolism and catabolism – Anabolism = building (condensation); Catabolism = breaking (hydrolysis).
• 12. Forgetting that condensation and hydrolysis are reversible – In principle, they are reversible, but in the cell, they are coupled to other reactions.

Quick Revision

• A compound which has high molecular weight and is made from many repeating units is known as a macromolecule or polymer.
• The individual units of a polymer are micromolecules and are called monomers.
• The interconversions of these molecules are carried out by condensation and hydrolysis.
• During condensation, when two monomers (e.g., Alpha-Glucose) join:
• A hydroxyl (-OH) group is removed from one monomer (first Alpha-Glucose).
• A hydrogen (-H) is removed from the other (second Alpha-Glucose).
• Water is released.
• A bond is formed between the monomers.
• The product (Maltose) of such a reaction is called a dimer.
• If the same reaction is repeated several times, the resulting molecule will be a polymer.
• For example, many Alpha-Glucose molecules condense to form Amylose, and many water molecules are released.
• The number of water molecules released during a condensation reaction depends upon the number of bonds formed.
• Example: 19 water molecules will be released when 20 monomers are condensed to form a polymer.
• Condensation is also called dehydration synthesis because water is removed (dehydration) and a bond is made (synthesis).
• Condensation does not take place unless:
• The proper enzyme is present.
• The monomers are in an activated energy-rich form.
• Hydrolysis is essentially the reverse of condensation, i.e., the breakdown of a dimer or polymer into its monomers by the addition of water.
• During hydrolysis:
• An (-OH) group from water is attached to one monomer.
• A (-H) is attached to the other monomer.
• For example, breakdown of Amylose in the presence of amylase enzyme and splitting of water molecule.

60-Second Revision

• Macromolecule/Polymer = large molecule made of repeating units
• Monomer = individual unit
• Condensation = joining monomers; water removed; bond formed
• Hydrolysis = breaking polymers; water added; bond broken
• Condensation = dehydration synthesis
• Hydrolysis = reverse of condensation
• Water released = n - 1 for n monomers
• Enzymes required for both
• **Condensation** = anabolic
• **Hydrolysis** = catabolic
• Examples:
• Condensation: Glucose + Glucose → Maltose + Water
• Hydrolysis: Maltose + Water → Glucose + Glucose
• Warning: Condensation removes water; hydrolysis adds water. Do not confuse the two. Condensation requires energy; hydrolysis releases energy. Both require specific enzymes. The number of water molecules released is n - 1, not n.