A Level Biology Lesson 2:
Making and Breaking Polymers
Task 1. Check Where this Lesson fits into your Exam Specification!
Task 2. Watch the Revision Notes Lesson in Full.
00:00 Intro Screen / Learning Outcomes
01:29 Condensation Reactions
03:52 Hydrolysis Reactions
Download, Print out & complete the accompanying Interactive Worksheet.
A-Level Biology: Biochemistry Lesson 2. Summary.
Carbohydrates (e.g. Starch and Glycogen), Proteins and Nucleic Acids (e.g. DNA and RNA) are Polymers – Long complex molecules made up from many repeating units known as monomers, which are linked together by specific covalent bonds. For example, the covalent bond that links monosaccharides together is known as a glycosidic bond, whereas the covalent bond that links amino acids together to form proteins is called a peptide bond.
Monomers Join together via condensation reactions.
Condensation reactions involve the removal of a water molecule (H2O) [a Hydrogen is removed from one monomer whilst a Hydrogen and Oxygen [OH - a Hydroxyl group] is removed from the other monomer] resulting in the formation of a covalent bond between the monomers being joined together.
Polymers are broken down (Hydrolysed) in a process called Hydrolysis.
Hydrolysis reactions are the exact opposite of condensation reactions, i.e. a water molecule (H2O) is utilised to “split” the covalent bond linking the monomers. The Hydrogen and the OH (Hydroxyl group) are added back to their respective monomers… (they are put back to where they were taken from!)
Check Your Spec!
★ AQA Specification Reference: - 3.1 Biological molecules. 3.1.1 Monomers and polymers. Monomers are the smaller units from which larger molecules are made. Polymers are molecules made from a large number of monomers joined together. A condensation reaction joins two molecules together with the formation of a chemical bond and involves the elimination of a molecule of water. A hydrolysis reaction breaks a chemical bond between two molecules and involves the use of a water molecule.
★ CIE Specification Reference: - 2 Biological molecules. Candidates will be expected to use the knowledge gained in this section to solve problems in familiar and unfamiliar contexts.
★ Edexcel (Biology A – Salters-Nuffield) Specification Reference: - Topic 1: Lifestyle, Health and Risk. Know how macromolecules are formed.
★ Edexcel (Biology B) Specification Reference: - Topic 1: Biological Molecules. The role of monomers in the synthesis of polymers and how the structure and properties of these relate to their functions are considered. Know how macromolecules are formed.
★ OCR (Biology A) Specification Reference: - Module 2: Foundations in biology: 2.1.2 Biological molecules. (b) the concept of monomers and polymers and the importance of condensation and hydrolysis reactions in a range of biological molecules.
★ OCR (Biology B) Specification Reference: - Module 2: Cells, chemicals for life, transport and gas exchange : 2.1.2 Water and its importance in plants and animals (d) the importance of hydrolysis and condensation of biological molecules.
★ WJEC Specification Reference: - Core Concepts 1. Chemical elements are joined together to form biological compounds.