A Level Biology with MR Nash – Topic 1 Biological Molecules 10

Molecules of Life Specification Point 3.1.1 The variety of life, both past and present, is extensive, but the biochemical basis of life is similar for all living things. Monomers are the smaller units from which larger molecules are made. Polymers are molecules made from a large number of monomers joined together. Monosaccharides, amino acids and nucleotides are examples of monomers. 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. 5

Lets get started: Making useful molecules Nylon (a type of plastic) is used for creating synthetic substances. Complete the chemical reaction below: Tube A contains the building blocks of nylon. Tube B contains a catalyst. Add tube A to tube B to make chemical C. Note what happens. Which chemical, A or C, is more useful? Explain why? What kind of reaction do you think has just happened? Outcomes: Define the terms monomer and polymer Describe the reactions that form and break polymers in biological molecules Use word and symbol equations to describe condensation and hydrolysis reactions 10 minutes to collect practical and write down some thoughts http://www.rsc.org/learn-chemistry/wiki/TeacherExpt:Making_nylon_-_the_%27nylon_rope_trick%27 Nylon – rope trick: 5 x 25 cm3 beaker A pair of tweezers. 2.2 g of 1,6-diaminohexane dissolved in 50 cm3 of deionised water in Beaker labelled A 1.5 g of decanedioyl dichloride dissolved in 50 cm3 of cyclohexane in Beaker labelled B

Polymerisation reaction Outcomes: Define the terms monomer and polymer Describe the reactions that form and break polymers in biological molecules Use word and symbol equations to describe condensation and hydrolysis reactions Monomer Monomer Dimer 10show diagram and explain that this s the reaction they have just done. And question students what do they think these terms mean. Go through the reaction (polymerisation) and explain key terms Then show the polymer part and explain that the reaction keeps happening until you get these large structures Polymer

Definitions Monomer: Dimer: Polymer: Polymerisation: Why is any of this important? Proteins, Carbohydrates, DNA, Fats these are all Polymers made of smaller monomer parts. Outcomes: Define the terms monomer and polymer Describe the reactions that form and break polymers in biological molecules Use word and symbol equations to describe condensation and hydrolysis reactions 5 minutes to write definitions.

Forming Polymers – Condensation reactions Outcomes: Define the terms monomer and polymer Describe the reactions that form and break polymers in biological molecules Use word and symbol equations to describe condensation and hydrolysis reactions 5 – discuss diagram and question why do they think its called a condensation reaction –link back to KS4. Challenge if they can write word equations for condensation reactions. Challenge why would this be important – to build proteins, carbohydrates, cells etc Condensation reaction: forms polymers by reacting the OH with the H. By product: Water (H2O)

Breaking down Polymers - Hydrolysis Outcomes: Define the terms monomer and polymer Describe the reactions that form and break polymers in biological molecules Use word and symbol equations to describe condensation and hydrolysis reactions Hydrolysis: Using water to break apart a polymer. What do you notice about the condensation reaction and the hydrolysis reaction? 5 same as before Challenge – word equations Challenge question on board Challenge why would this be important? (to break down molecules for energy) 10 Plenary – Triptico This is the Answer.

Why would it be important to build polymers? (Condensation) Examples of Polymers in Living things: Starch Cellulose Proteins Fats DNA Examples of Monomers in Living things: Glucose Amino acids Fatty acids Nucleic acids Why would it be important to build polymers? (Condensation) Why would it be important to break down polymers back into monomers? (Hydrolysis)