 Smaller organic molecules join together to
form larger molecules
 macromolecules
 4 major classes of macromolecules:
 carbohydrates
 lipids
 proteins
 nucleic acids
 Long molecules covalently bonded by linking chains
of repeating smaller units
 polymers
 monomers = repeated small units
 each cell has millions
of diff macromolecules
Think: 26 letters of
alphabet for all possible
combinations
 Hydrolysis
 use H2O to break apart monomers
 reverse of condensation reaction
 H2O is split into H and OH
 H & OH group attach where the covalent
bond used to be
 ex: digestion is
hydrolysis
 http://nhscience.lonestar.edu/biol/dehydrat/dehydrat.
html
 So what’s all this talk about carbs??
 Atkin’s Diet & South Beach Diet
1. contain C, H, O
2. 1:2:1 ratio
3. provide energy or storage
4. many end in “ose”
5. three main groups –
monosaccharides, disaccharides,
polysaccharides
 Carbohydrates are composed of C, H, O carbo -
hydr - ate
CH2O
(CH2O)x
C6H12O6
 Function:
 energy
 raw materials
energy storage
u structural materials
u
 Monomer: single sugar molecules
(monosaccharides)
 ex: sugars & starches
 Most names for sugars end in -ose
 Classified by number of carbons
 6C = hexose (glucose)
 5C = pentose (fructose, ribose)
 3C = triose (glyceraldehyde): imp
intermediate in metabolic process of cell
respiration (burning glucose for energy)
What functional groups?
carbonyl
aldehyde
ketone
hydroxyl
2005-2006
 5C & 6C sugars form rings in aqueous solutions
 in cells!
Carbons are numbered
C6'
5' C
O
4' C
C 1'
C 3'
C 2'
 Monosaccharides
 simple 1 monomer sugars
 glucose
 Disaccharides
 2 monomers
 sucrose
 Polysaccharides
 large polymers
 starch
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simplest form of carbohydrates
building blocks for larger carbohydrates
(also called monomers)
usually contain molecular formula C6H12O6
isomers: glucose, fructose, galactose
glucose (blood sugar), fructose & galactose (fruit
sugars)
can occur as straight (open) chains or as rings
numbering of carbon atoms in ring depends on
the straight chain (always # the carbon atoms so
that the carbon attached to the functional group
is the smallest number possible)
Glucose in the open chain and ring form
 Dehydration synthesis: putting together monomers by
taking out water (req’s energy & enzymes)
monosaccharides
|
glucose
|
fructose
structural isomers
“Let’s go to the video tape!”
(play movie here)
disaccharide
|
sucrose
glycosidic linkage: can be
alpha or beta which
changes the orientation
of the 2 monosaccharides
to each other
Lactose: β-1,4 linkage
(the 1,4 tells you where the 2
molecules are bonded to each
other)
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C12H22O11 (molecular formula)
2 monosaccharides joined
twice the energy
sucrose (table sugar) = 1 glucose + 1 fructose
maltose (found in sugar cane) =
1 glucose + 1 glucose
lactose (milk sugar) = 1 glucose + 1 galactose
maltose has alpha linkage (bottom to bottom)
sucrose has alpha linkage (bottom to bottom)
lactose has beta linkage (top to bottom)
1,4 or 1,2 numbering tells you what carbon
numbers the linkage is being formed at
 Polymers of sugars
 costs little energy to build
 easily reversible = release energy
 Function:
 energy storage
 starch (plants)
 glycogen (animals)
 building materials = structure
 cellulose (plants)
 chitin (arthropods & fungi)
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(C6H10O5)n [molecular formula]
N= 5-5,000 monosaccharides
Form chains of polymers
(repeating monomer units)
2 main functions: food storage and structure
Food storage
Structure
cellulose
plant starches animal starches
amylose amylopectin
glycogen
chitin
2005-2006
α -1,4 linkage on the straight chain
α -1,6 linkage at the branch points
(every 10 glucose molecules)
 Molecular structure determines function
isomers of glucose
u How does structure influence function…
u
Amylose:
straight chain with α -1,4 linkage
Amylopectin: - α -1,4 linkage on the straight chain with
α -1,6 linkage at the branch points (every 30 glucose
molecules)
Amylose
 straight chain that forms a
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helical structure in water
uses α glucose
α-1,4 linkage
used for storage (starch) in
plants
soluble in water
Cellulose
 straight chain
 uses β glucose
 β-1,4 linkage (every other
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glucose subunit is inverted)
cannot be digested by
animals (lack the enzyme
cellulase)
used for support
makes up plant cell walls
insoluble in water
Parallel cellulose molecules are held together by
hydrogen bonds.
 Most abundant
organic compound
on Earth
 Cross-linking
between polysaccharide
chains: rigid & hard
to digest
Think herbivores:
spend a lot of time
digesting food w/help
of microbes
Cow
can digest cellulose well; no
need to eat supplemental
sugars
Gorilla
can’t digest cellulose well; must
supplement with sugar source,
like fruit
2005-2006
 forms the exoskeletons
of arthropods
 used to make a strong
and flexible surgical
thread that decomposes
after the wound or
incision heals
 makes up the cell walls of
some fungi
The structure of the chitin monomer
 Which food will get into your
blood more quickly?

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
apple
rice cakes
corn flakes
bagel
peanut M&M
2005-2006
 Ranking of carbohydrates based on their immediate
effect on blood glucose (blood sugar) levels
 Carbohydrate foods that breakdown quickly during
digestion have the highest glycemic indices. Their
blood sugar response is fast & high.
2005-2006
 Which food will get into your
blood more quickly?

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
apple
rice cakes
corn flakes
bagel
peanut M&M
36
82
84
72
33
2005-2006
Let’s build some
Carbohydrates!