Ch. 5 - Macromolecules• Smaller organic molecules join together to
form larger molecules– macromolecules
• 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 (polymerization)– monomers
• building blocks• repeated small units
– covalent bonds
Dehydration synthesis
H2O
HO H
HO H HO H
How to break down a polymer• 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
HydrolysisDigestion
enzyme
OH
OH
H
H
HO
CH2OH
HH
H
OH
O
Carbohydratesenergy
molecules
Carbohydrates• Carbohydrates are composed of C, H, O
carbo - hydr - ateCH2O
• Function:– energy – energy storage – structural materials
• Monomer: simple sugars= glucose, fructose, galactose
sugar sugar sugar sugar sugar sugar sugarsugar
C6H12O6(CH2O)x
Numbered carbons
C
CC
C
CC
1'
2'3'
4'
5'6'
O
energy stored in C-C bonds
Simple & complex sugars• Monosaccharides
– simple 1 monomer sugars– These link to form:
• Disaccharides– 2 monomers– sucrose
• Polysaccharides – large chains of monosaccharides– Starch, glycogen
OH
OH
H
H
HO
CH2OH
HH
H
OH
O
Glucose
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
– costs little energy to build– easily reversible = release energy
• Function:– energy storage
• starch (plants)• glycogen (animals)
– in liver & muscles
– structure• cellulose (plants)• chitin (arthropods & fungi)
Polysaccharide diversity
• Molecular structure determines function
isomers of glucose structure determines function…
in starch in cellulose
Digesting starch vs. cellulose
starcheasy todigest enzyme
enzyme
cellulosehard todigest
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• Cell walls of plants!!
Chitin, a different structural polysaccharide
(a) The structure of the chitin monomer.
OCH2OH
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
Cowcan digest cellulose well, with the help of bacteria in gut, no need to eat other sugars
Gorillacan’t digest cellulose well; must add another sugar source, like fruit to diet
1. Which of the following is a polymer?A. Carbon atomsB. Simple sugar (aka monosaccharide)C. GlucoseD. CelluloseE. Deoxyribose
2. Starch and Glycogen both:I. Serve as energy storage for organismsII.Provide structure and supportIII. Are structural isomers of glucose
I onlyII onlyI and II onlyI and III onlyI, II, and III