Lecture 5 Lecture 5 Sept 9, 2005Sept 9, 2005MACROMOLECULES #1MACROMOLECULES #1

Carbohydrates Carbohydrates

And LipidsAnd Lipids

- Polymers - Polymers

-CarbohydratesCarbohydratesmonomers and polymersmonomers and polymers

- Lipids- Lipids

Lecture outline:Lecture outline:

Principles of Building Polymers:Principles of Building Polymers:

- biological polymers are built from biological polymers are built from simple simple small unitssmall units called called monomersmonomers

- addition of each monomeric unit occurs with theaddition of each monomeric unit occurs with theremoval of a removal of a water moleculewater molecule

A A condensation dehydrationcondensation dehydration reaction reaction

- ends are chemically distinct ends are chemically distinct directionalitydirectionality of synthesis of synthesis

- requires requires energy inputenergy input for polymerization; for polymerization;uses carrier molecules to activate monomersuses carrier molecules to activate monomers

MODULAR DESIGN

SIMPLICITY AND VERSATILITYASSEMBLY-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-OH H-YYY-OH H-ZZZZZ-OH

H-XXXX- YYY-ZZZZZ-OH

HOH HOH

Hydrolysisdeath by water

Monomers

Polymer

Endless variety of Polymers

Order of MonomersDifferent 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

HO H1 2 3 HO

HO H1 2 3 4

H

H2O

Short polymer Unlinked monomer

Longer polymer

Dehydration removes a watermolecule, forming a new bond

Figure 5.2A

• Polymers can disassemble by– Hydrolysis

(b) Hydrolysis of a polymer

HO 1 2 3 H

HO H1 2 3 4

H2O

HHO

Hydrolysis adds a watermolecule, breaking a bond

Figure 5.2B

Monomers Polymers

CARBOHYDRATESCARBOHYDRATESSugars and Sugar DerivativesSugars and Sugar Derivatives

Monosaccharides Polysaccharides

Simple Sugars

Glucose Fructose

Ribose

storagestarch: amylose amylopectin glycogen

structureFiber: cellulose

Monomers: Monomers: Polymers: Polymers:

Long chains of monomers

OligosaccharidesOligosaccharidesInformational structuresInformational structures

MONOSACCHARIDES = Carbohydrate Monomers

•1 Carbonyl - aldehyde or ketoneR-C-H R1-C-R2

==O O

•All Other CARBONS each have ONE alcohol group

R-OH

Expect them to be HYDROPHILICExpect them to be HYDROPHILIC

AldoAldosugarsugar

KetoKetosugarsugar

Triose sugars(C3H6O3)

Pentose sugars(C5H10O5)

Hexose sugars(C6H12O6)

H C OH

H C OH

H C OH

H C OH

H C OH

H C OH

HO C H

H C OH

H C OH

H C OH

H C OH

HO C H

HO C H

H C OH

H C OH

H C OH

H C OH

H C OH

H C OH

H C OH

H C OH

H C OH

C OC O

H C OH

H C OH

H C OH

HO C H

H C OH

C O

H

H

H

H H H

H

H H H H

H

H H

C C C COOOO

Ald

os

es

Glyceraldehyde

Ribose

Glucose Galactose

Dihydroxyacetone

Ribulose

Ke

tos

es

FructoseFigure 5.3

Monosaccharides Vary in length

3, 4, 5, 6 or 7 carbons

Carbon with Carbon with 4 different functional groups 4 different functional groups

Chiral or asymmetric carbonChiral or asymmetric carbon = = “handed” carbon“handed” carbon

Also differ by Also differ by SPATIAL GEOMETRYSPATIAL GEOMETRY

RightRighthandedhanded

““D” formD” form

LeftLefthandedhanded

““L” formL” form

Stereoisomers Stereoisomers not the same not the same

Plane Plane of of

symmetrysymmetry

Not chiralNot chiral

ChiralChiral

Not chiralNot chiral

ChiralChiral

ChiralChiral

ChiralChiral

Triose sugars(C3H6O3)

Pentose sugars(C5H10O5)

Hexose sugars(C6H12O6)

H C OH

H C OH

H C OH

H C OH

H C OH

H C OH

HO C H

H C OH

H C OH

H C OH

H C OH

HO C H

HO C H

H C OH

H C OH

H C OH

H C OH

H C OH

H C OH

H C OH

H C OH

H C OH

C OC O

H C OH

H C OH

H C OH

HO C H

H C OH

C O

H

H

H

H H H

H

H H H H

H

H H

C C C COOOO

Ald

os

es

Glyceraldehyde

Ribose

Glucose Galactose

Dihydroxyacetone

Ribulose

Ke

tos

es

FructoseFigure 5.3

Spatial Geometry yields a variety of forms

8 8 Forms!Forms!

5 and 6 Carbon Sugars CIRCULARIZE in WaterTo FORM RINGS

FischerFischerprojectionprojection

HaworthHaworthprojectionprojection

H

H C OH

HO C H

H C OH

H C OH

H C

O

C

H

1

2

3

4

5

6

H

OH

4C

6CH2OH 6CH2OH

5C

HOH

C

H OH

H

2 C

1C

H

O

H

OH

4C

5C

3 C

H

HOH

OH

H

2C

1 C

OH

H

CH2OH

H

H

OH

HO

H

OH

OH

H5

3 2

4

(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.

OH3

O H OO

6

1

Figure 5.4

Circularization causes another Circularization causes another chiralchiral carbon carbon

-D-Glucose-D-Glucose -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

HOH H

OH

O H

OH

CH2OH

H

HO

H

HOH

H

OH

O H

OH

CH2OH

H

O

H

HOH H

OH

O H

OH

CH2OH

H

H2O

H2O

H

H

O

H

HOH

OH

OH

CH2OH

CH2OH HO

OHH

CH2OH

HOH

H

H

HO

OHH

CH2OH

HOH H

O

O H

OHH

CH2OH

HOH H

O

HOH

CH2OH

H HO

O

CH2OH

H

H

OH

O

O

1 2

1 41– 4

glycosidiclinkage

1–2glycosidic

linkage

Glucose

Glucose Glucose

Fructose

Maltose

Sucrose

OH

H

H

Figure 5.5

monomeric sugars coupled together by

CONDENSATION REACTION

GlycosidicGlycosidicbondbond

Holds carbohydrates togetherHolds carbohydrates together

BreakdownBreakdownDoes notDoes notRequireRequireEnergyEnergyInputInput

SynthesisSynthesisRequires Requires

EnergyEnergyInputInput

Sucrose (glucose+ fructose) Cane SugarLactose (glucose+galactose) Milk SugarMaltose (glucose+glucose) Beer

Dextran (short chain of glucose) Digested StarchFurans (short chain of fructose) Onions

OligoSaccharides

DiSaccharides

Disaccharides, Oligosaccharides and Polysaccharides(two)(two) (few)(few) (many)(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 polysaccharideFigure 5.6

MitochondriaGiycogen granules

0.5 m

(b) Glycogen: an animal polysaccharide

Glycogen

Figure 5.6

Glycogen (or Amylopectin)Glycogen (or Amylopectin)

Polysaccharides of glucose chains inPolysaccharides of glucose chains inan a(1->4) linkage, with a(1->6) an a(1->4) linkage, with a(1->6) branchesbranches

Structural Polysaccharides

• CelluloseCellulose– Is also a polymer of glucose

– But has different glycosidic linkages than starch

– We can readily digest starchesbut 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

CH2OH

HOH H

H

OH

OHH

H

HO

4

C

C

C

C

C

C

H

H

H

HO

OH

H

OH

OH

OH

H

O

CH2OH

H

HH

OH

OHH

H

HO

4OH

CH2OH

O

OH

OH

HO

41

O

CH2OH

O

OH

OH

O

CH2OH

O

OH

OH

CH2OH

O

OH

OH

O O

CH2OH

O

OH

OH

HO4

O1

OH

O

OH OHO

CH2OH

O

OH

O OH

O

OH

OH

(a) and glucose ring structures

(b) Starch: 1– 4 linkage of glucose monomers

1

glucose glucose

CH2OH CH2OH

1 4 41 1

Figure 5.7 A–C

Starches: glycosidic linkage OH “down”

Cellulose: glycosidic linkage OH “up”

Cellulose ß(1->4) Cellulose ß(1->4) linkagelinkageAmylose a(1->4) Amylose a(1->4) linkagelinkage

Plant cells

0.5 m

Cell walls

Cellulose microfibrils in a plant cell wall

Microfibril

CH2OH

CH2OH

OH

OH

OO

OHO

CH2OHO

OOH

OCH2OH OH

OH OHO

O

CH2OH

OO

OH

CH2OH

OO

OH

O

O

CH2OHOH

CH2OHOH

OOH OH OH OH

O

OH OH

CH2OH

CH2OH

OHO

OH CH2OH

OO

OH CH2OH

OH

Glucose monomer

O

O

O

O

O

O

Parallel cellulose molecules areheld together by hydrogenbonds between hydroxyl

groups attached to carbonatoms 3 and 6.

About 80 cellulosemolecules associate

to form a microfibril, themain architectural unitof the plant cell wall.

A cellulose moleculeis an unbranched glucose polymer.

OH

OH

O

OOH

Cellulosemolecules

Figure 5.8

Polysaccharides Polysaccharides although although

hydrophillichydrophillicareare

generally generally Insoluble in waterInsoluble in water

-orders too much water around polymerorders too much water around polymer-Polymer tends to hydrogen bond to itselfPolymer tends to hydrogen bond to itself-Polymer falls out of solutionPolymer falls out of solution

Starch

““polymer effect”polymer effect”

Polymer forms Polymer forms

Secondary StructuresSecondary Structures

Polymer hydrogen bonding Polymer hydrogen bonding to to Itself Itself

If If Denature Denature Secondary Structure Secondary Structure

(Break Hydrogen Bonds of Polymer with Itself)(Break Hydrogen Bonds of Polymer with Itself)

Water will Hydrogen bondWater will Hydrogen bondWith PolymerWith Polymer

RESULT IS BOUND WATERRESULT IS BOUND WATER GELGEL

Can FORCE polymer to stay Hydrated Can FORCE polymer to stay Hydrated

Sugar DerrivativesSugar Derrivatives

DisruptDisruptSecondary Secondary StructuresStructures-remain remain Hydrated!Hydrated!

Characteristics?Characteristics?

Some OtherSugar Derivatives or Modified Sugars

Missing one or more components:

a. 5 carbon RIBOSE and DEOXYRIBOSE missing one alcohol

b. Glycerol - 3 Carbon Sugar withalcohol 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

- ---- -H H H

OH

OH

OH

HH

a.a.

b.b.

c.c.

Questions?Questions?

LIPIDSLIPIDShydrophobic characterhydrophobic character

TriglyceridesPhospholipids Steroids

“Other”

FATSOILS-long termstorage depot

MEMBRANESMembranes

Hormones

Fatty Acids and Glycerol

Fatty Acid: carboxylic acid with LONG hydrocarbon chain

F.A differ by:F.A differ by:

ChainChainlengthlength

saturationsaturation

• Fats– Are constructed from two types of smaller

molecules, a single glycerol and usually three fatty acids

(b) Fat molecule (triacylglycerol)

H HH H

HHH

HH

HH

HH

HH

HOH O HC

C

C

H

H OH

OH

H

HH

HH

HH

HH

HH

HH

HH

H

HCCC

CC

CC

CC

CC

CC

CC C

Glycerol

Fatty acid(palmitic acid)

H

H

H

H

HH

HH

HH

HH

HH

HH

HH

HH

HHHH

HHHHHHHHHHHH

H

HH

H HH

H HH

HH

HH

HH

HH

HHHHHHHHHHH

HH

H

H H H H H H H H HH

HH H H H

H

HH

HHHHHH

HHHHH

HH

HO

O

O

O

OC

C

C C C C C C C C C C C C C C C C C

C

CCCCCCC

CCCCCCCCC

C C C C C C C C C C C CC

CC

O

O

(a) Dehydration reaction in the synthesis of a fatEster linkage

Figure 5.11

Triglycerides: 3 fatty acids

linked to Glycerolby CONDENSATION

SYNTHESIS

ESTER LinkageESTER Linkage

Properties in WaterProperties in Water

Insoluble !Insoluble !AllAll

hydrophobichydrophobic

TriglyceridesTriglycerides

FATS OILSSolid 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 nicelyStack nicely

• Unsaturated fatty acids– Have one or more double bonds

(b) Unsaturated fat and fatty acidcis double bondcauses bending

Oleic acid

Figure 5.12

Do not Stack wellDo not Stack well

Free Fatty Acids

Hydrolyzed Triglycerides

PolarPolar(charged)(charged)HeadHead

Very Very HydrophobicHydrophobicTailTail

micellemicelle

FattyFattyAcidsAcids

monolayermonolayer

amphipathicamphipathic

PhospholipidsPhospholipids

NonpolarPolar

Fatty acid tails

Fatty acid tailsGly

cero

l

Phosphate

HeadGroup

Fig 3-27

Glycerol linked to 2 fatty acids

• Phospholipid structure– Consists of a hydrophilic “head” and

hydrophobic “tails”

CH2

O

PO O

O

CH2CHCH2

OO

C O C O

Phosphate

Glycerol

(a) Structural formula (b) Space-filling model

Fatty acids

(c) Phospholipid symbol

Hy

dro

ph

ob

ic t

ail

s

Hydrophilichead

Hydrophobictails

–

Hy

dro

ph

ilic

he

ad CH2 Choline

+

Figure 5.13

N(CH3)3

Phospholipid Head GroupsPhospholipid Head Groups

Hydrophillic! Polar groupsHydrophillic! Polar groups

Phospholipid BilayerPhospholipid Bilayer

Form Form BoundariesBoundaries

Hydrophilichead

WATER

WATER

Hydrophobictail

Figure 5.14

Nonpolar FA tailsNonpolar FA tails

Polar HeadgroupsPolar Headgroups

Polar HeadgroupsPolar Headgroups

3-D Ball (Sphere)

Vesicle or

Liposome Crosssection

Sheet

Inside

Outside

Hormones:Hormones:Signal moleculesSignal molecules

SummarySummary•Principles of Building PolymersPrinciples of Building Polymers

Directional assembly from simple unitsDirectional assembly from simple unitsRequires energy inputRequires energy inputCondensation dehydration reactionsCondensation dehydration reactions

•CarbohydratesCarbohydratesmonosaccharidesmonosaccharidespolysaccharidespolysaccharides

•LipidsLipidsTriglyceridesTriglyceridesphospholipidsphospholipidssteroidssteroids

Next Time:

More Macromolecules

Proteins Proteins

Nucleic AcidsNucleic Acids