The Structure and Function of Macromolecules Chapter carbohydrates

2 Macromolecules: The Molecules of Life Three of the four classes of life’s organic molecules are polymers: Three of the four classes of life’s organic molecules are polymers:  Carbohydrates  Proteins  Nucleic acids Lipids are not polymers, just large molecules Lipids are not polymers, just large molecules Nucleic Acids and Carbohydrates -- both monomers & polymers Nucleic Acids and Carbohydrates -- both monomers & polymers

3 The Synthesis and Breakdown of Polymers Monomers form polymers by condensation (or dehydration) reactions Monomers form polymers by condensation (or dehydration) reactions Polymers are disassembled to monomers by hydrolysis Polymers are disassembled to monomers by hydrolysis

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6 Macromolecules: The Molecules of Life Carbohydrates Carbohydrates Nucleic Acids Nucleic Acids Proteins Proteins Lipids Lipids

7 Carbohydrates – sugars and polymers of sugars Monosaccharides -- single sugars Monosaccharides -- single sugars Disaccharides – two sugars Disaccharides – two sugars Oligosaccharides -- three to nine sugars Oligosaccharides -- three to nine sugars Polysaccharides -- many sugar building blocks Polysaccharides -- many sugar building blocks

8 Sugars Monosaccharides -- CH 2 O Monosaccharides -- CH 2 O Glucose -- most common Glucose -- most common Classified by location of carbonyl group and number of carbons in skeleton Classified by location of carbonyl group and number of carbons in skeleton

LE 5-3 Triose sugars (C 3 H 6 O 3 ) Glyceraldehyde Aldoses Ketoses Pentose sugars (C 5 H 10 O 5 ) Ribose Hexose sugars (C 5 H 12 O 6 ) Glucose Galactose Dihydroxyacetone Ribulose Fructose

10 Though often drawn as a linear skeleton, in aqueous solutions they form rings

11 glucose

12 glucose

13 Formed when a dehydration reaction joins two shorter saccharides Formed when a dehydration reaction joins two shorter saccharides  Bond -- glycosidic linkage Disaccharides to Polysaccharides Glucose Maltose Fructose Sucrose Glucose Dehydration reaction in the synthesis of maltose Dehydration reaction in the synthesis of sucrose 1–4 glycosidic linkage 1–2 glycosidic linkage

Between hydroxyl in one monomer and hydroxyl in another (e.g., 1-4 in Maltose; 1-2 in Sucrose) Glucose Maltose Fructose Sucrose Glucose Dehydration reaction in the synthesis of maltose Dehydration reaction in the synthesis of sucrose 1–4 glycosidic linkage 1–2 glycosidic linkage Glycoside Linkage

15 Glycoside Linkage Two ring forms: alpha (  ) and beta (  ) Two ring forms: alpha (  ) and beta (  ) Note:  glucose == galactose ….. Note:  glucose == galactose …..

16 Glycoside Linkage Between hydroxyl in one monomer and hydroxyl in another Between hydroxyl in one monomer and hydroxyl in another  Maltose (malt sugar) = glucose + glucose  Lactose (milk sugar) = glucose + galactose

LE 5-5 Glucose Maltose Fructose Sucrose Glucose Dehydration reaction in the synthesis of maltose Dehydration reaction in the synthesis of sucrose 1–4 glycosidic linkage 1–2 glycosidic linkage COMMON DISACCHARIDES: Sucrose (table sugar) = glucose + fructose Maltose (malt sugar) = glucose + glucose Lactose (milk sugar) = glucose + galactose

Oligosaccharides Typically short chains (3-9) Typically short chains (3-9)  Fructose and Galactose most common monomers Often chemical markers Often chemical markers  ABO blood type Therapeutic to the gut flora Therapeutic to the gut flora Believed to play a part in fertilization Believed to play a part in fertilization 18

Polysaccharide Structure and function -- determined by monomers and positions of glycosidic linkages Structure and function -- determined by monomers and positions of glycosidic linkages 19

20 Carbohydrates serve as fuel and building material Source -- cellular respiration Source -- cellular respiration Storage -- polysaccharides Storage -- polysaccharides Structural components -- cell walls, microfibrils, chitin Structural components -- cell walls, microfibrils, chitin

© 2009 W.W. Norton & Company, Inc. DISCOVER BIOLOGY 4/e Cellular Respiration and Photosynthesis 21

22 RESPIRATION C 6 H 12 O 6 + O 2 CO 2 + H 2 O + ENERGY ATP 686 kcal/mole (180 grams)

23 Pyruvate Glucose CYTOSOL No O 2 present Fermentation or Anaerobic respiration Ethanol or lactate Acetyl CoA MITOCHONDRION O 2 present -- Aerobic cellular respiration Citric acid cycle Glycolysis …. What next? Glycolysis

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26 Photosynthesis Summarized 6 CO H 2 O + Light energy  C 6 H 12 O O H 2 O

27 Chloroplast   Gelatinous matrix called the stroma   Contains prokaryotic ribosomes, DNA   Carbohydrate synthesis occurs in the stroma   Folded membranes called thylakoids fill the stroma and form into stacks called grana

LE 10-5_2 H2OH2O LIGHT REACTIONS Chloroplast Light ATP NADPH O2O2 Light reactions (in the thylakoids) -- split water, release O2, produce ATP, and form NADPH

LE 10-5_3 H2OH2O LIGHT REACTIONS Chloroplast Light ATP NADPH O2O2 NADP + CO 2 ADP P + i CALVIN CYCLE [CH 2 O] (sugar) The Calvin cycle (in the stroma) -- forms sugar from CO2, using ATP and NADPH

Respiration & Photosynthesis Respiration C 6 H 12 O 6 + O 2  CO 2 + H 2 O + ENERGY Photosynthesis CO 2 + H 2 O  C 6 H 12 O 6 + O 2 + H 2 O CO 2 + H 2 O  C 6 H 12 O 6 + O 2 + H 2 O Light energy Light energy 30

31 Storage Polysaccharides Plants store surplus starch as granules within chloroplasts, leukoplasts, and other plastids Plants store surplus starch as granules within chloroplasts, leukoplasts, and other plastids ChloroplastStarch 1 µm Amylose Starch: a plant polysaccharide Amylopectin

32 Glycogen is the storage polysaccharide in animals Glycogen is the storage polysaccharide in animals Humans and other vertebrates store glycogen mainly in liver and muscle cells Humans and other vertebrates store glycogen mainly in liver and muscle cells Storage Polysaccharides Mitochondria Glycogen granules 0.5 µm Glycogen Glycogen: an animal polysaccharide

33 Structural Polysaccharides Cellulose -- plant cell walls Cellulose -- plant cell walls  Chitin -- cellulose-ish Polymers of glucose – different glycosidic linkages Polymers of glucose – different glycosidic linkages  alpha glucose – helical  beta glucose -- straight  In β glucose -- hydrogen bonds form between strands  strands group into microfibrils -- strong building materials for plants

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LE 5-8 Cellulose molecules Cellulose microfibrils in a plant cell wall Cell walls Microfibril Plant cells 0.5 µm  Glucose monomer

Cellulose vs Starch Enzymes that digest starch by hydrolyzing alpha linkages can’t hydrolyze beta linkages in cellulose Enzymes that digest starch by hydrolyzing alpha linkages can’t hydrolyze beta linkages in cellulose Cellulose in human food -- insoluble fiber Cellulose in human food -- insoluble fiber Some microbes use enzymes to digest cellulose Some microbes use enzymes to digest cellulose Many herbivores, from cows to termites, have symbiotic relationships with these microbes Many herbivores, from cows to termites, have symbiotic relationships with these microbes 36

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Chitin exoskeleton of arthropods exoskeleton of arthropods primary component of cell walls in fungi primary component of cell walls in fungi structurally – similar to cellulose structurally – similar to cellulose functionally – similar to protein keratin functionally – similar to protein keratin 38

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40 Sucralose Sucrose Sucralose Cl

41 Stevia Steviol Stevioside

Aspartame Aspartame is a methyl ester of aspartic acid and phenylalanine (2 amino acids). Aspartame is a methyl ester of aspartic acid and phenylalanine (2 amino acids). 42

Saccharine 43