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The Chemical Basis of Life-4 ORGANIC MOLECULES: 1. Carbohydrates Dr G. Tsheboeng 235/231 1 Recap: Making Biological Molecules and H2O Condensation Reaction 2 substances combine =...

The Chemical Basis of Life-4 ORGANIC MOLECULES: 1. Carbohydrates Dr G. Tsheboeng 235/231 1 Recap: Making Biological Molecules and H2O Condensation Reaction 2 substances combine = form one new compound plus water H2O Hydrolysis Reaction Water is “added” to one compound = it breaks into 2 bits 2  E.g. Hydrolysis reaction 6CO2 + 6H2O + Energy -> C6H12O6 + 6O2 (photosynthesis) Condensation reaction C6H12O6 + 6O2 -> 6CO2 + 6 H2O+ Energy (686 kcal). (respiration) 3  Lesson objectives To define organic molecules To list examples of functional groups To discuss the synthesis of organic molecules To discuss the different types of carbohydrates 4  Organic molecules What is an organic molecule? A molecule that is normally found in or produced by living systems.. Typically consists of carbon atoms in rings or long chains,  where other atoms (e.g. hydrogen, oxygen, and nitrogen) are attached. 5  Molecules are the building blocks of life The chemistry of carbon: o Biological molecules consist mainly of carbon atoms o Bonded to other carbon atoms o Or to atoms of O, S, N or H o Can form 4 covalent bonds o Carbon molecules can form straight chains, branches or rings 6 These generate a lot of molecular structures & shapes 7  Hydrocarbons Only contain carbon & hydrogen Covalent between carbon & hydrogen energy rich Because of these they make good fuels 8 Examples of hydrocarbons 9 Gasoline used for fuel in cars is also rich in energy 10  Functional groups Due to similar electro-negativities, C-C & C-H hydrocarbon molecules are non-polar However, most organic molecules contain other atoms These atoms often have different electro- negativities Hence they are polar 11  Remember: Electronegativities of elements important to life Element Electronegativity Oxygen 3.5 Chlorine 3.1 Nitrogen 3.0 Carbon 2.5 Phosphorous 2.1 Hydrogen 2.1 Sodium 0.9 Potassium 0.8 12  Specific groups attached to C-H molecules are called functional groups E.g. –OH (hydroxyl group) Functional groups maintain their chemical properties Biological chemical reactions involve functional groups 13 More examples of functional groups 14  Building Biological Molecules and H2O Condensation/dehydration Reaction 2 substances combine = form one new compound plus water H2O Hydrolysis Reaction Water is “added” to one compound = it breaks into 2 bits 15  Remember… Hydrolysis reaction 6CO2 + 6H2O + Energy -> C6H12O6 + 6O2 (photosynthesis) Condensation reaction C6H12O6 + 6O2 -> 6CO2 + 6 H2O+ Energy (686 kcal). (respiration) 16 Making Biological Molecules Condensation Hydrolysis 17  Condensation reaction Called dehydration synthesis because – OH group & H are removed H2O removed Energy is required to break the chemical bonds as water is removed Cell must supply energy to build macromolecules 18  Hydrolysis Reverse of dehydration Molecule of water is added Release the energy that was stored in the bonds 19  Four main categories of Organic molecules Carbohydrates Proteins Lipids and Nucleic acids ( DNA and RNA) 20  Carbohydrates Carbohydrates are the main energy source for living things The name "carbohydrate" means a "hydrate of carbon.“ Chemically, carbohydrates are organic molecules in which carbon, hydrogen, and oxygen bond together in the ratio: Cx(H2O)y where x and y are whole numbers that differ depending on the specific carbohydrate 21 Carbohydrates are made from simple sugars 22 Carbohydrates Make up a large group of molecules o Have similar atomic compositions o Differ in size, chemical properties & biological functions 23  Carbohydrates have four major biological roles They are used as a source of stored energy They are used to transport stored energy within complex organisms They serve as carbon skeletons that can be rearranged to form new molecules They form extracellular assemblies such as cell walls that provide structure to organisms 24  Monosaccharides are simple sugars All living things contain the monosaccharide glucose o It is the “blood sugar” o Used to store & transport energy in in humans o Exists in straight chains and ring forms o Ring forms dominant because they are stable in water 25  Four categories of biologically important Carbohydrates All carbohydrates are made up of units of sugar (also called saccharide units). Simple sugars = carbohydrates that contain a single sugar unit = monosaccharides (Monomers) or Two sugar units = disaccharides (Dimers) Three-twenty= Oligosaccharides (oligo, “several”) Many sugar units (>2) = polysaccharides (Polymers) 26  Types of sugars An aldose is a monosaccharide (a simple sugar) that contains only one aldehyde (-CH=O) group per molecule. A ketose is a sugar containing one ketone (-C=O) group per molecule 27 Examples of ketoses and aldoses 28  Different Monosaccharides contain different numbers of carbons The building blocks of all higher carbohydrates. All have a general molecular formula (CH2O)n. further classified, based on the number of carbon atoms in a molecule Trioses - contain 3 carbon atoms: glyceraldehyde Tetroses - contain 4 carbon atoms: malate Pentoses - contain 5 carbon atoms: ribose, deoxyribose, ribulose hexoses - contain 6 carbon atoms: glucose, fructose, galactose 29  Some monosaccharides are structural Isomers Are compounds with the same O H O H molecular formula but different structural formulas. C C Isomers have different H – C – OH HO – C – H arrangements of atoms. HO – C – H H – C – OH H – C – OH HO – C – H H – C – OH HO – C – H CH2OH CH2OH D-glucose L-glucose 30  D-Glucose: Three hydroxyl groups & one hydrogen group are on the right side L-Glucose: They are on the left 31 Three Monosaccharides C6H12O6 32 Structural differences between Glucose, Galactose & Fructose 33 34 35  Glycosidic bonds link monosaccharides Disaccharides Made up of combination of 2 monosaccharides Could be the same or different types of monosaccharides Sucrose, common “table sugar”, consists of a glucose unit bonded to a fructose unit The 2 monosaccharides form covalent bonds The covalent bonds are called glycosidic bonds The bonding results in loss of an H2O molecule 36  Formation of Disaccharides Same monomers Different monomers NB: dehydration 37 Common table sugar- Different monomers 38 Breaking up: hydrolysis NB: Digestion of sucrose 39  Transport disaccharides Most organisms transport glucose in their bodies In humans it is transported as monosaccharide In plants & other organisms it is converted in transport form 40  In transport form is less readily metabolized Transported in disaccharide form Disaccharide is effective glucose reservoir Glucose utilizing enzymes cannot use it Enzymes that can break are only found in the tissues where it should be used 41  E.g. of transport disaccharides Sucrose (Glucose + Fructose) in plants Glucose + Galactose= Lactose in mammals Adults have reduced levels of lactase Therefore cannot use lactose efficiently 42  Polysaccharides…. Consist of several hundred monosaccharide units forming giant chains of monosaccharides joined by glycosidic bonds Polysaccharides are not soluble in water The monosaccharide units may be of the same type or different types If same type = homopolysaccharide Starch & cellulose = made up of glucose only If different types = heteropolysaccharide 43  Polysaccharides store energy & provide structural materials 44 Important Polysaccharides: Storage: starch & glycogen Consists of glucose Glycogen: subunits shorter chains Product of photosynthesis Plant energy storage molecule Glycogen is a similar molecule in animals. Starch and glycogen can be digested by animals. 45 Important Polysaccharides: Structural: Cellulose Composed of glucose subunits Different bond from starch formed Structural component in plants cell walls Cannot be digested by animals 46 Important Polysaccharides: Structural: Chitin Glucose subunits Partly derived from non-sugars (nitrogen) Composes exoskeletons of insects Water proof Note similarity to cellulose. 47 48  Summary Questions Comments 49 The Chemical Basis of Life-4 ORGANIC MOLECULES: 1. Carbohydrates Dr G. Tsheboeng 235/231 1 Recap: Making Biological Molecules and H2O Condensation Reaction 2 substances combine = form one new compound plus water H2O Hydrolysis Reaction Water is “added” to one compound = it breaks into 2 bits 2  E.g. Hydrolysis reaction 6CO2 + 6H2O + Energy -> C6H12O6 + 6O2 (photosynthesis) Condensation reaction C6H12O6 + 6O2 -> 6CO2 + 6 H2O+ Energy (686 kcal). (respiration) 3  Lesson objectives To define organic molecules To list examples of functional groups To discuss the synthesis of organic molecules To discuss the different types of carbohydrates 4  Organic molecules What is an organic molecule? A molecule that is normally found in or produced by living systems.. Typically consists of carbon atoms in rings or long chains,  where other atoms (e.g. hydrogen, oxygen, and nitrogen) are attached. 5  Molecules are the building blocks of life The chemistry of carbon: o Biological molecules consist mainly of carbon atoms o Bonded to other carbon atoms o Or to atoms of O, S, N or H o Can form 4 covalent bonds o Carbon molecules can form straight chains, branches or rings 6 These generate a lot of molecular structures & shapes 7  Hydrocarbons Only contain carbon & hydrogen Covalent between carbon & hydrogen energy rich Because of these they make good fuels 8 Examples of hydrocarbons 9 Gasoline used for fuel in cars is also rich in energy 10  Functional groups Due to similar electro-negativities, C-C & C-H hydrocarbon molecules are non-polar However, most organic molecules contain other atoms These atoms often have different electro- negativities Hence they are polar 11  Remember: Electronegativities of elements important to life Element Electronegativity Oxygen 3.5 Chlorine 3.1 Nitrogen 3.0 Carbon 2.5 Phosphorous 2.1 Hydrogen 2.1 Sodium 0.9 Potassium 0.8 12  Specific groups attached to C-H molecules are called functional groups E.g. –OH (hydroxyl group) Functional groups maintain their chemical properties Biological chemical reactions involve functional groups 13 More examples of functional groups 14  Building Biological Molecules and H2O Condensation/dehydration Reaction 2 substances combine = form one new compound plus water H2O Hydrolysis Reaction Water is “added” to one compound = it breaks into 2 bits 15  Remember… Hydrolysis reaction 6CO2 + 6H2O + Energy -> C6H12O6 + 6O2 (photosynthesis) Condensation reaction C6H12O6 + 6O2 -> 6CO2 + 6 H2O+ Energy (686 kcal). (respiration) 16 Making Biological Molecules Condensation Hydrolysis 17  Condensation reaction Called dehydration synthesis because – OH group & H are removed H2O removed Energy is required to break the chemical bonds as water is removed Cell must supply energy to build macromolecules 18  Hydrolysis Reverse of dehydration Molecule of water is added Release the energy that was stored in the bonds 19  Four main categories of Organic molecules Carbohydrates Proteins Lipids and Nucleic acids ( DNA and RNA) 20  Carbohydrates Carbohydrates are the main energy source for living things The name "carbohydrate" means a "hydrate of carbon.“ Chemically, carbohydrates are organic molecules in which carbon, hydrogen, and oxygen bond together in the ratio: Cx(H2O)y where x and y are whole numbers that differ depending on the specific carbohydrate 21 Carbohydrates are made from simple sugars 22 Carbohydrates Make up a large group of molecules o Have similar atomic compositions o Differ in size, chemical properties & biological functions 23  Carbohydrates have four major biological roles They are used as a source of stored energy They are used to transport stored energy within complex organisms They serve as carbon skeletons that can be rearranged to form new molecules They form extracellular assemblies such as cell walls that provide structure to organisms 24  Monosaccharides are simple sugars All living things contain the monosaccharide glucose o It is the “blood sugar” o Used to store & transport energy in in humans o Exists in straight chains and ring forms o Ring forms dominant because they are stable in water 25  Four categories of biologically important Carbohydrates All carbohydrates are made up of units of sugar (also called saccharide units). Simple sugars = carbohydrates that contain a single sugar unit = monosaccharides (Monomers) or Two sugar units = disaccharides (Dimers) Three-twenty= Oligosaccharides (oligo, “several”) Many sugar units (>2) = polysaccharides (Polymers) 26  Types of sugars An aldose is a monosaccharide (a simple sugar) that contains only one aldehyde (-CH=O) group per molecule. A ketose is a sugar containing one ketone (-C=O) group per molecule 27 Examples of ketoses and aldoses 28  Different Monosaccharides contain different numbers of carbons The building blocks of all higher carbohydrates. All have a general molecular formula (CH2O)n. further classified, based on the number of carbon atoms in a molecule Trioses - contain 3 carbon atoms: glyceraldehyde Tetroses - contain 4 carbon atoms: malate Pentoses - contain 5 carbon atoms: ribose, deoxyribose, ribulose hexoses - contain 6 carbon atoms: glucose, fructose, galactose 29  Some monosaccharides are structural Isomers Are compounds with the same O H O H molecular formula but different structural formulas. C C Isomers have different H – C – OH HO – C – H arrangements of atoms. HO – C – H H – C – OH H – C – OH HO – C – H H – C – OH HO – C – H CH2OH CH2OH D-glucose L-glucose 30  D-Glucose: Three hydroxyl groups & one hydrogen group are on the right side L-Glucose: They are on the left 31 Three Monosaccharides C6H12O6 32 Structural differences between Glucose, Galactose & Fructose 33 34 35  Glycosidic bonds link monosaccharides Disaccharides Made up of combination of 2 monosaccharides Could be the same or different types of monosaccharides Sucrose, common “table sugar”, consists of a glucose unit bonded to a fructose unit The 2 monosaccharides form covalent bonds The covalent bonds are called glycosidic bonds The bonding results in loss of an H2O molecule 36  Formation of Disaccharides Same monomers Different monomers NB: dehydration 37 Common table sugar- Different monomers 38 Breaking up: hydrolysis NB: Digestion of sucrose 39  Transport disaccharides Most organisms transport glucose in their bodies In humans it is transported as monosaccharide In plants & other organisms it is converted in transport form 40  In transport form is less readily metabolized Transported in disaccharide form Disaccharide is effective glucose reservoir Glucose utilizing enzymes cannot use it Enzymes that can break are only found in the tissues where it should be used 41  E.g. of transport disaccharides Sucrose (Glucose + Fructose) in plants Glucose + Galactose= Lactose in mammals Adults have reduced levels of lactase Therefore cannot use lactose efficiently 42  Polysaccharides…. Consist of several hundred monosaccharide units forming giant chains of monosaccharides joined by glycosidic bonds Polysaccharides are not soluble in water The monosaccharide units may be of the same type or different types If same type = homopolysaccharide Starch & cellulose = made up of glucose only If different types = heteropolysaccharide 43  Polysaccharides store energy & provide structural materials 44 Important Polysaccharides: Storage: starch & glycogen Consists of glucose Glycogen: subunits shorter chains Product of photosynthesis Plant energy storage molecule Glycogen is a similar molecule in animals. Starch and glycogen can be digested by animals. 45 Important Polysaccharides: Structural: Cellulose Composed of glucose subunits Different bond from starch formed Structural component in plants cell walls Cannot be digested by animals 46 Important Polysaccharides: Structural: Chitin Glucose subunits Partly derived from non-sugars (nitrogen) Composes exoskeletons of insects Water proof Note similarity to cellulose. 47 48  Summary Questions Comments 49