Macromolecules

4 major classes of macromolecules:carbohydrateslipidsproteinsnucleic acids

– monomers • building blocks• repeated small units

– polymers • Molecules consisting of 2 or more

monomers

Dehydration synthesis / CondensationDehydration synthesis / Condensation

3

H2O

HO

HO H

H HHO

Polymer Formation (synthesis)

-joins monomers by “taking” H2O out• one monomer donates OH–

• other monomer donates H+ • together these form H2O• requires energy & enzymes

enzymeDehydration synthesis / CondensationDehydration synthesis / Condensation

4

H2O

HO H

HO H HO H

Polymer Breakdown (digestion)

– use H2O to breakdown polymers • reverse of dehydration synthesis

• cleave off one monomer at a time

• H2O is split into H+ and OH–

– H+ & OH– attach to ends

– requires enzymes– releases energy

enzymeHydrolysisHydrolysis

Carbohydrates -Composed of C, H, O carbo-hydrate CH2O

C6H12O6

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

6C = hexose (glucose) 5C = pentose (ribose) 3C = triose (glyceraldehyde)

*5C & 6C sugars form rings in solution

6

Types of Carbohydrates

• Monosaccharides– 1 simple sugar (monomers)– glucose, galactose, fructose

• Disaccharides– 2 monosaccharides – sucrose, maltose, lactose

• Polysaccharides – 3 or more monosaccharides

(polymers)– starch, cellulose, chitin, glycogen

OH

OH

H

H

HO

CH2OH

HH

H

OH

O

Glucose

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glucose glucose maltose 1,4 glycosidic linkage

*Position of linkage determines function

glucose fructose sucrose 1,2 glycosidic linkage

8

Polysaccharides Polymers of sugars Function:

energy storage starch (plants) glycogen (animals)

structure = building materials cellulose (plants) chitin (arthropods & fungi)

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Unbranched vs Branched

starch(plant)

glycogen(animal)

p62 Fig 5.6

10

Structural PolysaccharidesCellulose makes up plant cell walls and differs from starch by glycosidic linkagesp63 Fig 5.7

starch cellulose

*isomers of glucose

alpha = below plane....all beta = above plane....every other

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Digesting starch vs. cellulose

cellulosehard todigest

cellulosehard todigest

starcheasy todigest

starcheasy todigest

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Structure

Cellulose -straight -chains...H-bonds

Starch-helical

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