Lecture 5 Sept 9, 2005 MACROMOLECULES #1 Carbohydrates And Lipids

- Polymers -Carbohydrates monomers and polymers - Lipids Lecture outline:

Principles of Building Polymers: - biological polymers are built from simple small units called monomers - addition of each monomeric unit occurs with the removal of a water molecule A condensation dehydration reaction - ends are chemically distinct directionality of synthesis - requires energy input for polymerization; uses carrier molecules to activate monomers

MODULAR DESIGN SIMPLICITY AND VERSATILITY ASSEMBLY-LINE MENTALITY Don’t have to make every structure from scratch Simplified chemistry, repeating link Dehydration Synthesis

Dehydration Synthesis make by taking water away H-XXXX-OHH-YYY-OHH-ZZZZZ-OH H-XXXX-YYY-ZZZZZ-OH HOH Hydrolysis death by water Monomers Polymer

Endless variety of Polymers Order of Monomers Different Amounts of each monomer H-YYY-XXXX-ZZZZZ-OH H-XXXX-ZZZZZ-YYY-OH H-XXXX-YYY-ZZZZZ-OH H-ZZZZZ-YYY-ZZZZZ-OH

Monomers form larger molecules by condensation reactions called dehydration reactions (a) Dehydration reaction in the synthesis of a polymer HOH H H H2OH2O Short polymer Unlinked monomer Longer polymer Dehydration removes a water molecule, forming a new bond Figure 5.2A

Polymers can disassemble by –Hydrolysis (b) Hydrolysis of a polymer HO H H H2OH2O H Hydrolysis adds a water molecule, breaking a bond Figure 5.2B

Monomers Polymers

CARBOHYDRATES Sugars and Sugar Derivatives Monosaccharides Polysaccharides Simple Sugars Glucose Fructose Ribose storage starch: amylose amylopectin glycogen structure Fiber: cellulose Monomers: Polymers: Long chains of monomers Oligosaccharides Informational structures

MONOSACCHARIDES = Carbohydrate Monomers 1 Carbonyl - aldehyde or ketone R-C-H R 1 -C-R 2 == O O All Other CARBONS each have ONE alcohol group R-OH Expect them to be HYDROPHILIC Aldosugar Ketosugar

Triose sugars (C 3 H 6 O 3 ) Pentose sugars (C 5 H 10 O 5 ) Hexose sugars (C 6 H 12 O 6 ) H C OH HO C H H C OH HO C H H C OH C O H C OH HO C H H C OH C O H H H HHH H H HHH H H H C CCC O O O O Aldoses Glyceraldehyde Ribose Glucose Galactose Dihydroxyacetone Ribulose Ketoses Fructose Figure 5.3 Monosaccharides Vary in length 3, 4, 5, 6 or 7 carbons

Carbon with 4 different functional groups Chiral or asymmetric carbon = “handed” carbon Also differ by SPATIAL GEOMETRY

Righthanded “D” form Lefthanded “L” form Stereoisomers not the same Planeofsymmetry

Not chiral Chiral Chiral Not chiral Chiral Chiral Chiral

Triose sugars (C 3 H 6 O 3 ) Pentose sugars (C 5 H 10 O 5 ) Hexose sugars (C 6 H 12 O 6 ) H C OH HO C H H C OH HO C H H C OH C O H C OH HO C H H C OH C O H H H HHH H H HHH H H H C CCC O O O O Aldoses Glyceraldehyde Ribose Glucose Galactose Dihydroxyacetone Ribulose Ketoses Fructose Figure 5.3 Spatial Geometry yields a variety of forms 8Forms!

5 and 6 Carbon Sugars CIRCULARIZE in Water To FORM RINGS Fischerprojection Haworthprojection

H H C OH HO C H H C OH H C O C H H OH 4C4C 6 CH 2 OH 5C5C H OH C H OH H 2 C 1C1C H O H OH 4C4C 5C5C 3 C H H OH OH H 2C2C 1 C OH H CH 2 OH H H OH HO H OH H (a) Linear and ring forms. Chemical equilibrium between the linear and ring structures greatly favors the formation of rings. To form the glucose ring, carbon 1 bonds to the oxygen attached to carbon 5. OH 3 O H O O 6 1 Figure 5.4

Circularization causes another chiral carbon  -D-Glucose  -D-Glucose

Dehydration reaction in the synthesis of maltose. The bonding of two glucose units forms maltose. The glycosidic link joins the number 1 carbon of one glucose to the number 4 carbon of the second glucose. Joining the glucose monomers in a different way would result in a different disaccharide. Dehydration reaction in the synthesis of sucrose. Sucrose is a disaccharide formed from glucose and fructose. Notice that fructose, though a hexose like glucose, forms a five-sided ring. (a) (b) H HO H H OH H OH O H CH 2 OH H HO H H OH H OH O H CH 2 OH H O H H OH H OH O H CH 2 OH H H2OH2O H2OH2O H H O H HO H OH O H CH 2 OH HO OH H CH 2 OH H OH H H HO OH H CH 2 OH H OH H O O H OH H CH 2 OH H OH H O H OH CH 2 OH H HO O CH 2 OH H H OH O O – 4 glycosidic linkage 1–2 glycosidic linkage Glucose Fructose Maltose Sucrose OH H H Figure 5.5 monomeric sugars coupled together by CONDENSATION REACTION Glycosidicbond Holds carbohydrates together

Breakdown Does not RequireEnergyInput SynthesisRequiresEnergyInput

Sucrose (glucose+ fructose)Cane Sugar Lactose (glucose+galactose)Milk Sugar Maltose (glucose+glucose)Beer Dextran (short chain of glucose) Digested Starch Furans (short chain of fructose)Onions OligoSaccharides DiSaccharides Disaccharides, Oligosaccharides and Polysaccharides (two)(few)(many)

Polysaccharides Long chains of Millions of monomers most common polymers made ONLY of GLUCOSE monomers Storage reserves: Starch amylose amylopectin, glycogen Structure: cellulose Chloroplast Starch Amylose Amylopectin 1  m (a) Starch: a plant polysaccharide Figure 5.6

Mitochondria Giycogen granules 0.5  m (b) Glycogen: an animal polysaccharide Glycogen Figure 5.6

Glycogen (or Amylopectin) Polysaccharides of glucose chains in an a(1->4) linkage, with a(1->6) branches

Structural Polysaccharides CelluloseCellulose –Is also a polymer of glucose –But has different glycosidic linkages than starch –We can readily digest starches but cannot digest cellulose

Cellulose is indigestable to animals –Cows and termites have microbes in their stomachs to facilitate this process Figure 5.9

(c) Cellulose: 1– 4 linkage of  glucose monomers H O O CH 2 OH H OH H H H H HO 4 C C C C C C H H H OH H H O CH 2 OH H H H OH H H HO 4 OH CH 2 OH O OH HO 4 1 O CH 2 OH O OH O CH 2 OH O OH CH 2 OH O OH O O CH 2 OH O OH HO 4 O 1 OH O O CH 2 OH O OH O O (a)  and  glucose ring structures (b) Starch: 1– 4 linkage of  glucose monomers 1  glucose  glucose CH 2 OH Figure 5.7 A–C Starches:   glycosidic linkage OH “down” Cellulose:   glycosidic linkage OH “up”

Cellulose ß(1->4) linkage Amylose a(1->4) linkage

Plant cells 0.5  m Cell walls Cellulose microfibrils in a plant cell wall  Microfibril CH 2 OH OH OHOH O O O CH 2 OH O O OH O CH 2 OH OH O O CH 2 OH O O OHOH O O OHOH O O OH CH 2 OHOH O O CH 2 OH OH O CH 2 OH O O OHCH 2 OH OH  Glucose monomer O O O O O O Parallel cellulose molecules are held together by hydrogen bonds between hydroxyl groups attached to carbon atoms 3 and 6. About 80 cellulose molecules associate to form a microfibril, the main architectural unit of the plant cell wall. A cellulose molecule is an unbranched  glucose polymer. OH O O Cellulose molecules Figure 5.8

Polysaccharides although hydrophillic aregenerally Insoluble in water -orders too much water around polymer -Polymer tends to hydrogen bond to itself -Polymer falls out of solution Starch “polymer effect”

Polymer forms Secondary Structures Polymer hydrogen bonding to Itself

If Denature Secondary Structure (Break Hydrogen Bonds of Polymer with Itself) Water will Hydrogen bond With Polymer RESULT IS BOUND WATER GEL

Can FORCE polymer to stay Hydrated Sugar Derrivatives DisruptSecondaryStructures -remain Hydrated! Characteristics?

Some Other Sugar Derivatives orModified Sugars Missing one or more components: a. 5 carbon RIBOSE and DEOXYRIBOSE missing one alcohol b. Glycerol - 3 Carbon Sugar with alcohol in place of an aldehyde c. Sugar amines, Sugar acids have amine or carboxylic acid group or something else in place of an alcohol H - C - C - C - H HHH OH H a. b. c.

Questions?

LIPIDS hydrophobic character TriglyceridesPhospholipids Steroids “Other” FATS OILS -long term storage depot MEMBRANES Membranes Hormones Fatty Acids and Glycerol

Fatty Acid: carboxylic acid with LONG hydrocarbon chain F.A differ by: Chainlength saturation

Fats –Are constructed from two types of smaller molecules, a single glycerol and usually three fatty acids (b) Fat molecule (triacylglycerol) H H H H H H H H H H H H H H H H O Figure 5.11

Triglycerides: 3 fatty acids linked to Glycerol by CONDENSATION SYNTHESIS ESTER Linkage

Properties in Water Insoluble ! Allhydrophobic Triglycerides

FATSOILS Solid Liquid WHY? Saturated Unsaturated or Polyunsaturated Like Fig 3-28

Saturated fatty acids –Have the maximum number of hydrogen atoms possible –Have no double bonds (a) Saturated fat and fatty acid Stearic acid Figure 5.12 Stack nicely

Unsaturated fatty acids –Have one or more double bonds (b) Unsaturated fat and fatty acid cis double bond causes bending Oleic acid Figure 5.12 Do not Stack well

Free Fatty Acids Hydrolyzed Triglycerides Polar(charged)Head VeryHydrophobicTail micelle FattyAcids monolayer amphipathic

Phospholipids Nonpolar Polar Fatty acid tails Glycerol Phosphate Head Group Fig 3-27 Glycerol linked to 2 fatty acids

Phospholipid structure –Consists of a hydrophilic “head” and hydrophobic “tails” CH 2 O P O O O CH CH 2 OO C O C O Phosphate Glycerol (a) Structural formula (b) Space-filling model Fatty acids (c) Phospholipid symbol Hydrophobic tails Hydrophilic head Hydrophobic tails – Hydrophilic head CH 2 Choline + Figure 5.13 N(CH 3 ) 3

Phospholipid Head Groups Hydrophillic! Polar groups

Phospholipid Bilayer FormBoundaries

Hydrophilic head WATER Hydrophobic tail Figure 5.14 Nonpolar FA tails Polar Headgroups

3-D Ball (Sphere) Vesicle or Liposome Cross section Sheet Inside Outside

Hormones: Signal molecules

Summary Principles of Building PolymersPrinciples of Building Polymers Directional assembly from simple units Requires energy input Condensation dehydration reactions CarbohydratesCarbohydratesmonosaccharidespolysaccharides LipidsLipidsTriglyceridesphospholipidssteroids

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