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Macromolecules

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Macromolecules Smaller organic molecules join

together to form larger moleculesMacromolecules

4 major classes of macromoleculesCarbohydrates

Lipids

Proteins

Nucleic acids

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Polymers

Long molecules built by linking chain of repeating smaller units

Polymers

Monomers = repeated small units

Covalent bonds

Fig. 5-2a

Dehydration removes a watermolecule, forming a new bond

Short polymer Unlinked monomer

Longer polymer

Dehydration reaction in the synthesis of a polymer

HO

HO

HO

H2O

H

HH

4321

1 2 3

(a)

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How to build a polymer Condensation reaction

Dehydration synthesis

Joins monomers by “taking” water out1 monomer provides OH

Other monomer provides H

Together they form water

Requires energy and enzymes

Fig. 5-2b

Hydrolysis adds a watermolecule, breaking a bond

Hydrolysis of a polymer

HO

HO HO

H2O

H

H

H321

1 2 3 4

(b)

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How to break down a polymer Hydrolysis

Use water to break apart monomersReverse of condensation reaction

Water is split into H and OH

H and OH group attach where the covalent bond used to be

Example:

digestion is hydrolysis

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Carbohydrates

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Carbohydrates Composed of C,H,O

Carbo –hydr --ateCH2O(CH2)x C6H12O6

FunctionEnergy Raw materialsEnergy storageStructural materials

Monomer: sugars Example: sugars and starches

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Sugars

Most names for sugars end in –ose Classified by number of carbons

6C = hexose (glucose)

5C = pentose (fructose, ribose)

3C = triose (glyceraldehyde)

Dihydroxyacetone

Ribulose

Ket

ose

sA

ldo

ses

Fructose

Glyceraldehyde

Ribose

Glucose Galactose

Hexoses (C6H12O6)Pentoses (C5H10O5)Trioses (C3H6O3)

Functional Groups?

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Sugar structure

5C and 6C sugars form rings in aqueous solutions

In cells!

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Numbered carbons

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Simple and complex sugars

MonosaccharidesSimple 1 monomer sugarsGlucose

Disaccharides2 monomersSucrose

PolysaccharidesLarge polymersstarch

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Building sugars

Dehydration synthesis

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Building sugars

Dehydration synthesis

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Polysaccharides

Polymers of sugarsCosts little energy to build

Easily reversible = release energy

FunctionEnergy storage

Starch (plants)

Glycogen (animals)

Building materials – structureCellulose (plants)

Chitin (arthropods and fungi)

Fig. 5-6

(b) Glycogen: an animal polysaccharide

Starch

GlycogenAmylose

Chloroplast

(a) Starch: a plant polysaccharide

Amylopectin

Mitochondria Glycogen granules

0.5 µm

1 µm

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Polysaccharide diversity

Molecular structure determines function

Isomers of glucose

How does structure influence function….

Glucose Glucose

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Digesting starch vs. cellulose

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

(c) Cellulose: 1–4 linkage of glucose monomers

Fig. 5-9

Glucosemonomer

Cellulosemolecules

Microfibril

Cellulosemicrofibrilsin a plantcell wall

0.5 µm

10 µm

Cell walls

Cellulose is most abundant organic compound on earth

Fig. 5-10

The structureof the chitinmonomer.

(a) (b) (c)Chitin forms theexoskeleton ofarthropods.

Chitin is used to makea strong and flexiblesurgical thread.