Chapter 5: Macromolecules Macromolecules Large organic molecules built by smaller molecules. 4 major...
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Transcript of Chapter 5: Macromolecules Macromolecules Large organic molecules built by smaller molecules. 4 major...
Macromolecules• Large organic molecules built by smaller
molecules.• 4 major classes of
macromolecules:– carbohydrates– lipids– proteins– nucleic acids
H2O
HO
HO H
H HHO
Polymers:• Long molecules built by linking repeating
building blocks in a chain – Monomers are small building blocks – covalent bonds between
Dehydration synthesis
H2O
HO
HO H
H HHO
To build a polymerTake out water: called dehydration synthesis or condensation reaction:
– joins monomers by “taking” H2O out• one monomer loses OH–
• other monomer loses H+
– requires energy & enzymes
enzymeDehydration synthesis
Condensation reaction
H2O
HO H
HO H HO H
To break down a polymerAdd H2O to breakdown polymers
• reverse of dehydration synthesis
• H2O is split into H+ and OH–
– H+ & OH– attach to ends
– requires enzymes– releases energy
Hydrolysis
Digestion
enzyme
Carbohydrates- composed of C, H, O
Carb-o – hydrateUsed for:
– energy – energy storage– raw materials – structural materials
– Building blocks are sugars
sugar sugar sugar sugar sugar sugar sugarsugar
Sugars: end in -ose
• Monosaccharides: glucose fructose• Disaccharides: glucose + fructose = sucrose
• Others: maltose, lactose, dextrose
Simple & complex sugars• Monosaccharides
1 monomer – glucose
• Disaccharides2 monomers– sucrose
• Polysaccharides – large polymers– starch
Building sugars• Dehydration synthesis
glycosidic linkage
|glucose
|glucose
monosaccharides disaccharide
|maltose
H2O
Building sugars• Dehydration synthesis
|fructose
|glucose
monosaccharides
|sucrose
(table sugar)
disaccharide
H2O
Polysaccharides • Polymers of sugars• Function:
– energy storage • starch (plants)• glycogen (animals)
Glucose stored in liver
– structure• cellulose (plants)• chitin (arthropods & fungi)
Chitin: polysaccharide in lobster shells, insect bodies
(a) The structure of the chitin monomer.
O
CH2OH
OHH
H OH
H
NH
C
CH3
O
H
H
(b) Chitin forms the exo- skeleton of arthropods. This
cicada is molting, shedding its old exoskeleton and emergingin adult form. It is also found in
Fungal Cell Walls.
(c) Chitin is used to make a strong and flexible surgical
thread that decomposes after the wound or incision heals.
OH
Linear vs. branched polysaccharides
starch(plant)
glycogen(animal)
energystorag
e
slow release
fast release
Polysaccharides
• Molecular structure determines function
isomers of glucose structure determines function…
in starch in cellulose
Cellulose • Most abundant organic
compound on Earth– herbivores have evolved a mechanism to digest
cellulose– most carnivores have not
• that’s why they eat meat to get their energy & nutrients
• cellulose = undigestible roughage