Campbell Biology Chapter 5 PDF

Campbell Biology Third Canadian Edition Chapter 5 The Structure and Function of Large Biological Molecules Copyright © 2021 Pearson Canada, Inc. 5-1 Key Concepts Macromolecules are polymers, built from monomers Carbohydrates serve as fuel and building material Lipids are a diverse group of hydrophob...

Campbell Biology Third Canadian Edition Chapter 5 The Structure and Function of Large Biological Molecules Copyright © 2021 Pearson Canada, Inc. 5-1 Key Concepts Macromolecules are polymers, built from monomers Carbohydrates serve as fuel and building material Lipids are a diverse group of hydrophobic molecules Proteins include a diversity of structures, resulting in a wide range of functions Nucleic acids store, transmit, and help express hereditary information Genomics and proteomics have transformed biological inquiry and applications Copyright © 2021 Pearson Canada, Inc. 5-2 Overview: The Molecules of Life (1 of 2) All living things are made up of four classes of large biological molecules: – carbohydrates – lipids – proteins – nucleic acids Copyright © 2021 Pearson Canada, Inc. 5-3 Overview: The Molecules of Life (2 of 2) Macromolecules are large and complex molecules that are composed of many covalently connected atoms Molecular structure and function are inseparable Figure 5.1 Why is the structure of a protein important for its function? Copyright © 2021 Pearson Canada, Inc. 5-4 Concept 5.1: Macromolecules are Polymers, Built from Monomers A polymer is a long molecule consisting of many similar building blocks The smaller, repeating molecules that serve as building blocks are called monomers Three of life’s organic molecules are polymers: – Carbohydrates – Proteins – Nucleic acids Copyright © 2021 Pearson Canada, Inc. 5-5 The Synthesis and Breakdown of Polymers (1 of 3) A dehydration reaction occurs when two monomers bond together through the loss of a water molecule – Enzyme-catalyzed reactions Figure 5.2a The synthesis and breakdown of polymers. Copyright © 2021 Pearson Canada, Inc. 5-6 The Synthesis and Breakdown of Polymers (2 of 3) Animation: Polymers Right-click slide / select “Play” Copyright © 2021 Pearson Canada, Inc. 5-7 The Synthesis and Breakdown of Polymers (3 of 3) Polymers are disassembled into monomers by hydrolysis reactions, which are essentially the reverse of dehydration reactions Figure 5.2b The synthesis and breakdown of polymers. Copyright © 2021 Pearson Canada, Inc. 5-8 The Diversity of Polymers Each cell has thousands of different macromolecules Macromolecule content varies among cell types, varies more between individuals of a species, and even more between different species An immense variety of polymers can be built from a small set of monomers Copyright © 2021 Pearson Canada, Inc. 5-9 Concept 5.2: Carbohydrates Serve as Fuel and Building Material Carbohydrates include sugars and polymers of sugars The simplest carbohydrates are monosaccharides, or single sugars Carbohydrate macromolecules are polysaccharides, which are polymers composed of many sugar building blocks Copyright © 2021 Pearson Canada, Inc. 5 - 10 Sugars Monosaccharides have molecular formulas that are usually multiples of CH2O Glucose (C6H12O6) is the most common monosaccharide Monosaccharides are classified by – Location of the carbonyl group – Number of carbons in the carbon skeleton Copyright © 2021 Pearson Canada, Inc. 5 - 11 The Structure and Classification of Some Monosaccharides: Trioses Figure 5.3a The structure and classification of some monosaccharides. Copyright © 2021 Pearson Canada, Inc. 5 - 12 The Structure and Classification of Some Monosaccharides: Pentoses Figure 5.3b The structure and classification of some monosaccharides. Copyright © 2021 Pearson Canada, Inc. 5 - 13 The Structure and Classification of Some Monosaccharides: Hexoses Figure 5.3c The structure and classification of some monosaccharides. Copyright © 2021 Pearson Canada, Inc. 5 - 14 Sugars (1 of 3) Often drawn as linear skeletons; but in aqueous solutions many sugars form rings Monosaccharides serve as a major fuel source for cells and as raw material for building larger organic molecules Figure 5.4 Linear and ring forms of glucose. Copyright © 2021 Pearson Canada, Inc. 5 - 15 Sugars (2 of 3) A disaccharide forms when a dehydration reaction joins two monosaccharides This bond is called a glycosidic linkage Figure 5.5b Examples of disaccharide synthesis. Copyright © 2021 Pearson Canada, Inc. 5 - 16 Sugars (3 of 3) Animation: Disaccharide Right-click slide / select “Play” Copyright © 2021 Pearson Canada, Inc. 5 - 17 Polysaccharides Polysaccharides are polymers of sugar that have storage and structural roles The structure and function of a polysaccharide are determined by – its sugar monomers, and – the positions of its glycosidic linkages Copyright © 2021 Pearson Canada, Inc. 5 - 18 Storage Polysaccharides (1 of 2) Starch, a storage polysaccharide of plants, consists entirely of glucose monomers Plants store surplus starch as granules within chloroplasts, and other plastids Figure 5.6a Polysaccharides of plants and animals. Copyright © 2021 Pearson Canada, Inc. 5 - 19 Storage Polysaccharides (2 of 2) Glycogen is a storage polysaccharide in animals Glycogen is mainly in liver and muscle cells – Hydrolysis of glycogen releases glucose when the demand for energy increases Figure 5.6b Polysaccharides of plants and animals. Copyright © 2021 Pearson Canada, Inc. 5 - 20 Structural Polysaccharides (1 of 5) Cellulose is a major component of plant cell walls Cellulose is a polymer of glucose, but its glycosidic linkages differ from those of starch Figure 5.6c Polysaccharides of plants and animals. Copyright © 2021 Pearson Canada, Inc. 5 - 21 Structural Polysaccharides (2 of 5) Animation: Polysaccharides Right-click slide / select “Play” Copyright © 2021 Pearson Canada, Inc. 5 - 22 Structural Polysaccharides (3 of 5) The glycosidic linkages of cellulose differ from those of starch because the ring forms of glucose in the two polymers are slightly different – Cellulose contains beta (β) glucose instead of alpha (α) glucose as in starch Figure 5.7 Starch and cellulose structures. Copyright © 2021 Pearson Canada, Inc. 5 - 23 Structural Polysaccharides (4 of 5) Enzymes that hydrolyze (or digest) α linkages in starch cannot hydrolyze β linkages in cellulose Cellulose in human food passes through digestive tract as insoluble fibre Some microbes have enzymes that digest cellulose Herbivores, from cows to termites, have symbiotic relationships with these microbes Copyright © 2021 Pearson Canada, Inc. 5 - 24 Structural Polysaccharides (5 of 5) Chitin, also a structural polysaccharide, is found in arthropod exoskeletons Chitin also provides structural support for fungal cell walls Figure 5.8 Chitin, a structural polysaccharide. Copyright © 2021 Pearson Canada, Inc. 5 - 25