1.4 - Carbohydrates Notes PDF

REVIEW: MACROMOLECULES A large molecule (polymer) made of many smaller structural units (monomers) linked together There are four major groups of biologically important macromolecules: 1. Carbohydrates 2. Lipids...

REVIEW: MACROMOLECULES A large molecule (polymer) made of many smaller structural units (monomers) linked together There are four major groups of biologically important macromolecules: 1. Carbohydrates 2. Lipids 3. Proteins 4. Nucleic acids Condensation/Dehydration Synthesis Reaction (dehydration - water removed; synthesis - production of new molecules) Macromolecules are assembled in the same way: Monomers 🡪 Polymer o Anabolic reaction – small subunits built into larger molecules - (Small🡪 Big) o Energy is required o Water is released / formed Hydrolysis Reaction (hydro -water; lysis –broken) Macromolecules are disassembled in the same way: Polymer 🡪 Monomer o Catabolic reaction - large molecules are broken down into small subunits = (Big🡪 Small) o Energy is released o Water is used / added  CARBOHYDRATES FUNCTION OF CARBOHYDRATES Used as sources of energy o Glucose: primary source of energy o Sucrose/Lactose: dietary sugar Building materials Cell surface markers for cell-to-cell communication Contain C, H, O in a 1: 2: 1ratio Formula: (CH2O)n (n = # of Carbons) Sugar names end in -ose Simple Carbohydrates: Monosaccharide and Disaccharide Complex Carbohydrates:: Polysaccharide and Oligosaccharide SIMPLE CARBOHYDRATES Monosaccharides The smallest structural unit (monomer) of a carbohydrate C6H12O6 o Glucose o Fructose o Galactose Polar Hydrophilic (soluble in water) Carbohydrates are Characterized by: Number of carbons ○ ie. ribose has 5 carbons, glucose has 6 carbon Functional Groups ○ An –OH group is attached to each carbon except one, which is double bonded to a carbonyl group (=O) ○ glucose and galactose have an aldehyde group while fructose has a ketone group * Molecules with 5 or more carbons are linear in dry state but will naturally form a ring structure in water Carbonyl – Aldehyde VS Ketone Aldehyde ○ At the end of molecule ○ Must have a hydrogen attached to the C=O ○ The R group can be another hydrogen or a hydrocarbon Ketone ○ Within the molecule (middle) ○ Both R groups must be hydrocarbons Numbering the Carbons Number the carbons starting right 🡪left Isomers are monosaccharides with the same chemical formula but different arrangement of atoms i.e. C6H12O6 is glucose, galactose and fructose α-Glucose vs. β-Glucose When a glucose molecule forms a six-carbon ring… 50% chance the -OH will be below the plane (alpha) 50% chance the -OH will be above the plane (beta) SIMPLE CARBOHYDRATES Disaccharides Composed of two monosaccharides (monomers) joined through a condensation reaction, forming a glycosidic linkage (covalent bonds) glucose + glucose = maltose - Ex. Infant formula, Beer - glucose + fructose = sucrose - Ex. Sugar cane, Table Sugar - glucose + galactose = lactose - Ex. Milk Disaccharides/Polysaccharides can be broken down through a hydrolysis reaction COMPLEX CARBOHYDRATES Oligosaccharides 3 - 10 monosaccharides linked glucose + galactose + fructose = Raffinose o Found in beans, peas, lentils, broccoli, asparagus *Humans lack enzymes to digest oligosaccharides (causes bloating, cramps, gas) Polysaccharides > 10 monosaccharides linked Most are made up of hundreds of monosaccharides bonded together Types: 1. Starch: glucose storage in plants 2. Glycogen: glucose storage in animals 3. Dietary Fiber: not used for energy - Cellulose: structural support in plants - Chitin: structural support in organisms 1. Starch A starch molecule contains hundreds of glucose molecules in either o branched chains: amylopectin o unbranched (coiled) chains: amylose Sources: grains, dried beans, pasta, bread, potato 2. Glycogen Found in liver and skeletal muscles Many branch points allows for rapid break down for glucose to be released and used for energy 3. Dietary Fiber Group of plant polysaccharides that are not digested or absorbed in the human intestine; structural Fibers: 1. Cellulose 2. Chitin Cellulose Structural in plant cell walls Difficult for humans to digest Also used by humans in ○ wood for lumber and paper ○ cotton and linen for clothing Straight chain polymer of 𝛃 1-4 glycosidic linkages Chitin Add nitrogen containing group to C2 Structure supports ○ exoskeleton of insects, crabs, lobsters, fungi cell wall Also used in medicine ○ contact lenses, surgical thread DIGESTION OF CARBOHYDRATES Goal: Breakdown of large, complex molecules into small, absorbable monosaccharides Enzymes (-ase) are important for this Enzymes in small intestine ○ Sucrases: sucrose 🡪 glucose + fructose ○ Lactase: lactose 🡪 glucose + galactose ○ Maltase: maltose 🡪 glucose + glucose