a. 1.2 BIOLOGICAL MOLECULES LECTURE NOTES 2023.pdf

CATHOLIC JUNIOR COLLEGE H2 Biology JC1 CORE IDEA 1] THE CELL AND BIOMOLECULES OF LIFE 1.2] BIOMOLECULES OF LIFE Narrative from H2 Biology 9744 Syllabus: The focus of this topic is on how the structures of biomolecules give rise to properties that allow these biomolecules to carry out their functions...

CATHOLIC JUNIOR COLLEGE H2 Biology JC1 CORE IDEA 1] THE CELL AND BIOMOLECULES OF LIFE 1.2] BIOMOLECULES OF LIFE Narrative from H2 Biology 9744 Syllabus: The focus of this topic is on how the structures of biomolecules give rise to properties that allow these biomolecules to carry out their functions. Biomolecules form the bases of how organisms are able to perform their respective functions. For example, the properties of proteins allow them to play a variety of roles in structural, transport, enzymatic and signalling functions. This topic focuses on the structure and properties of biomolecules and how underlying chemical concepts explain these properties. Guided Questions from H2 Biology 9744 Syllabus:  How are the structures of biomolecules related to their functions? LEARNING OUTCOMES 1B and 1C Candidates should be able to: Subtopic Learning Outcomes 1B and 1C Pg Biomolecules of Life LO1B(a) Describe the structure and properties of the following monomers: i. α-glucose and β-glucose (in carbohydrates) 7-8  Carbohydrates LO1B(b) Describe the formation and breakage of the following bonds: 9-10 i. glycosidic bond LO1B(c) Describe the structures and properties of the following biomolecules and explain how these are related to their roles in living organisms: i. starch (including amylose and amylopectin) 11-13 ii. cellulose 16-18 iii. glycogen 14-15 Biomolecules of Life LO1B(a) Describe the structure and properties of the following monomers: ii. glycerol and fatty acids (in lipids) 21  Lipids LO1B(b) Describe the formation and breakage of the following bonds: 22-24 ii. ester bond LO1B(c) Describe the structures and properties of the following biomolecules and explain how these are related to their roles in living organisms: iv. triglyceride 22-25 v. phospholipid 26-28 Biomolecules of Life LO1B(a) Describe the structure and properties of the following monomers: iii. amino acids (in proteins) (chemical formulae of specific R groups of different 30-32  Proteins amino acids are not required) LO1B(b) Describe the formation and breakage of the following bonds: 33 iii. peptide bond LO1C(a) Explain primary structure, secondary structure, tertiary structure and 35-43 quaternary structure of proteins, and describe the types of bonds that hold the molecule in shape (hydrogen, ionic, disulphide bonds and hydrophobic interactions). 44 LO1C(b) Explain the effects of temperature and pH on protein structure. LO1C(c) Describe the molecular structure of the following proteins and explain how the structure of each protein relates to the function it plays: 46-47 i. haemoglobin (transport) 48-50 ii. collagen (structural) (to be iii. G-protein linked receptor (signaling) covered (Details of the number of amino acids and types of secondary structures in 3.3) present are not required.) Biology Department Catholic Junior College 1 CONTENT PAGE CONTENT PAGE 1 Introduction to Biomolecules of Life 3 1.1] Classes of Biomolecules 3 1.2] Monomers and Polymers 3 2 Biomolecule of Life - Carbohydrates 4-19 2.1] Monosaccharides - α-glucose and β-glucose 7-8 2.2] Formation and Breakage of Glycosidic Bond 9-10 2.3] Polysaccharide – Starch 11-12 Linking Structure and Property to Role in Living Organisms 13 2.4] Polysaccharide – Glycogen 14 Linking Structure and Property to Role in Living Organisms 15 2.5] Polysaccharide –Cellulose 16-17 Linking Structure and Property to Role in Living Organisms 18 2.6] Comparison of Polysaccharides 19 3 Biomolecule of Life - Lipids 20-28 3.1] Glycerol 21 3.2] Fatty acids 21 3.3] Triglyceride 22-24 Structure of Triglyceride 22 Formation and Breakage of Ester Bond 23-24 Linking Structure to Function 25 3.4] Phospholipid 26-28 Structure of Phospholipid 26-27 Linking Structure to Function 28 4 Biomolecule of Life - Proteins 29-34 4.1] Amino acids 30-32 4.2] Formation and Breakage of Peptide bond 33 4.3] Formation of Polypeptide 34 5 Structure of Proteins 35-43 5.1] Primary Structure 36 5.2] Secondary Structure 36-37 5.3] Tertiary Structure 38 5.4] Quaternary Structure 39 5.5] Bonds and Interactions holding Protein molecules in Shape 40-42 6 Factors affecting Protein Structure 43-44 6.1] Effect of Temperature on Protein Structure 43 6.2] Effect of pH on Protein Structure 43-44 7 Relating Structure of Proteins to their Function 45-50 7.1] Haemoglobin (Transport) 45-46 7.2] Collagen (Structural) 47-49 Comparison between Haemoglobin and Collagen 50 Biology Department Catholic Junior College 2 1] INTRODUCTION TO BIOMOLECULES OF LIFE BASIC CONCEPT MAP FOR BIOMOLECULES OF LIFE Biomolecules of Life Carbohydrates Lipids Proteins Nucleic acids Starch Triglyceride Collagen *DNA Glycogen Phospholipid Haemoglobin *RNA Cellulose *DNA and RNA will be covered in Topic 2.1 The Structure of Nucleic Acids and Genetic Expression 1.1] CLASSES OF BIOMOLECULES There are four major classes of biological molecules: A] Carbohydrates B] Lipids C] Proteins D] Nucleic Acids 1.2] MONOMERS AND POLYMERS  The four classes of biological molecules are often called macromolecules because of their large size.  Carbohydrates, lipids, proteins, and nucleic acids are also called polymers (poly: many) because they are made up of many identical singular building blocks called monomers (mono: one).  Monomers are covalently linked together to form polymers through condensation reactions (condense: ‘produce’ water) which are also known as dehydration reactions (removal of water), which involve the production of water as a by-product that is removed from the monomers (Fig. 1).  Each monomer after the formation of a polymer is called a residue (left behind). e.g. glucose residue.  Polymers can be broken apart to form monomers through hydrolysis reactions (hydro: water, lysis: separate), which involve the addition of water (Fig. 2).  All condensation and hydrolysis reactions are catalysed by enzymes; they are not spontaneous reactions. Fig. 2: Hydrolysis reaction Fig. 1: Condensation reaction Biology Department Catholic Junior College 3 2] BIOMOLECULE OF LIFE - CARBOHYDRATES CONCEPT MAP FOR CARBOHYDRATES - 1 Biological Molecules Carbohydrates Lipids Proteins Nucleic acids 1] Starch Triglyceride Collagen DNA 2] Glycogen Phospholipid Haemoglobin RNA 3] Cellulose CONCEPT MAP FOR CARBOHYDRATES - 2 CARBOHYDRATES are made of monomers called Monosaccharide e.g. glucose, galactose and fructose that can undergo condensation reaction (s) to form Disaccharide Polysaccharide [Only two [3 or more monosaccharides] monosaccharides] e.g. lactose, maltose e.g. starch, glycogen and sucrose and cellulose Biology Department Catholic Junior College 4 2] BIOMOLECULE OF LIFE - CARBOHYDRATES CARBOHYDRATES are substances which contain the elements carbon, hydrogen and oxygen.  They have a general formula Cx(H2O)y, where x and y are variable numbers.  All monosaccharides and some disaccharides, such as maltose and lactose, are reducing sugars (they can act as reducing agents in redox reactions).  Sucrose is a non-reducing sugar. MONOSACCHARIDES are the monomers or the basic building blocks of carbohydrates.  Examples of monosaccharides are glucose, fructose, and galactose (Fig 3a). Glucose is the most common monosaccharide and is an important substrate for cellular respiration.  In monosaccharides, all the carbon atoms except one have hydroxyl groups (-OH group) attached. Hydroxyl groups are polar (directionally charged) that readily form hydrogen bonds (Fig 3b) with water. Therefore, all monosaccharides are soluble in water. Fig. 3a: (a) Glucose monosaccharide; (b) Fructose monosaccharide. Fig. 3b: Example of polar molecules – water, and a hydrogen bond between two water molecules. Biology Department Catholic Junior College 5 2] BIOMOLECULE OF LIFE - CARBOHYDRATES DISACCHARIDES  Maltose (malt sugar) is a reducing sugar and comprises of two glucose molecules.  Lactose (milk sugar) is a reducing sugar and comprises glucose and galactose (Fig. 4a).  Sucrose (cane sugar) is a non-reducing sugar, and comprises glucose and fructose (Fig. 4b). (a) (b) Fig. 4a: Structure of lactose Fig. 4b: Structure of sucrose POLYSACCHARIDES are polymers formed by condensation of many monosaccharides. They function mainly as food and energy stores (e.g. starch and glycogen) and as structural support (e.g. cellulose). Fig. 5: Structure of Polysaccharides - Starch, Glycogen and Cellulose Biology Department Catholic Junior College 6 2] BIOMOLECULE OF LIFE - CARBOHYDRATES 2.1] MONOSACCHARIDE - α-glucose and β-glucose Biomolecules LO1B(a) Describe the structure and properties of the following monomers: of Life i. α-glucose and β-glucose (in carbohydrates) STRUCTURE OF GLUCOSE  Glucose has the molecular formula: C6H12O6.  Glucose can alternate between an ‘open chain’ or ‘ring’ structure (Fig. 6) in a solution spontaneously. i. Oxygen is part of the ring and carbon atom number 6 sticks up out of the ring (Fig. 6). ii. The ring structure is the more stable form, and only a small proportion (about