TJC IP3 Biomolecules Carbohydrates Notes

1 Temasek Junior College IP3 Biology Topic: Biomolecules – Carbohydrates Notes _________________________________________________________________ Learning Outcomes Candidates should be able to: (a) Describe the structure of carbohydrates, lipids and proteins and state their role in living organisms. [O and A-levels] (b) Describe the formation and breakage of the following bonds: [A-levels] ▪ glycosidic bond ▪ ester bond ▪ peptide bond (c) Define the terms with a named example of the primary structure, secondary structure, tertiary structure and quaternary structure and the bonds involved in each level of structure (details of secondary structure not needed). [A-levels] (d) Explain how the structure of the following biomolecules relate to their roles in living organisms: [A-levels] ▪ starch ▪ glycogen ▪ haemoglobin Use the knowledge gained in this section in new situations or to solve related problems. Outline I. Introduction II. Structure of carbohydrates III. Functions of carbohydrates IV. Tests for carbohydrates Think Cycle ✓ Know This study source was downloaded by 100000857398866 from CourseHero.com on 02-21-2025 20:46:29 GMT -06:00 https://www.coursehero.com/file/237244889/21-Biomolecules-Carbohydrates-Notespdf/

2 I. INTRODUCTION ▪ Carbohydrates are substances that contain the elements carbon, hydrogen and oxygen. ▪ They have the general formula Cx(H2O)y, where x and y are variable numbers. II. STRUCTURE OF CARBOHYDRATES ▪ Carbohydrates are divided into three main classes: − Monosaccharides − Disaccharides − Polysaccharides 1. Monosaccharides  Defined as a carbohydrate which cannot be hydrolysed to simpler carbohydrate.  The general formula is (CH2O)n  Common examples are glucose, fructose and galactose (hexose sugars) Fig.1.1 Structure of Monosaccharides LO (a), (b) glucose galactose fructose This study source was downloaded by 100000857398866 from CourseHero.com on 02-21-2025 20:46:29 GMT -06:00 https://www.coursehero.com/file/237244889/21-Biomolecules-Carbohydrates-Notespdf/

3 2. Disaccharides  A disaccharide is formed by a condensation reaction between two monosaccharides – one molecule of water is removed from the pair of monosaccharides (Fig. 1.2 & 1.3).  Common examples of disaccharides are - maltose = glucose + glucose - lactose = glucose + galactose - sucrose = glucose + fructose Fig.1.2 Structure of Disaccharides  The bond formed between the 2 monosaccharides is called the glycosidic bond. Fig. 1.3 Formation of disaccharides via condensation reaction glucose glucose maltose glucose fructose sucrose glycosid