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Biological Molecules
Focus on Carbohydrates
(See pages 31-41)
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MACROMOLECULE
(Polymers)
MONOMER
Carbohydrates
Monosaccharides
(Simple Sugars)
Proteins
Amino Acids
Lipids (Fats)
Fatty Acids and
Glycerol
Nucleotides
Nucleic Acids
(DNA/RNA)
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General Reactions
MONOMERS
Hydrolysis
Dehydration
Synthesis
5H2O
5H2O
POLYMER
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Carbohydrates
Carbohydrates are polymers of monosaccharides
(simple sugars).
 They are the first macromolecule to be
metabolized within the cells of the body (ie. they
are involved in cellular respiration before fats
and proteins, meaning that they are the
PRIMARY source of energy for the body).
 Cellular Respiration (Mitochondria):
6CO2 + 6H2O + ATP
Glucose + 6O2
(C6H12O6)
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Glucose is a simple sugar and the main monomer of
carbohydrates (polysaccharides) in the body.
Carbohydrates are broken down by the digestive
system, first in the mouth, then in the small intestine.
The final result of digestion is GLUCOSE which is
small enough to enter the bloodstream and
eventually, cells.
Aside from providing energy, carbohydrates also
associate with both the phospholipids and proteins
of cell membranes, in order to provide each cell with
an “I.D. tag” for cell-to-cell recognition.
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
There are three levels of carbohydrate structure based
purely on size differences:
1. Monosaccharides (One simple sugar):
Three major types:
A. Glucose – the primary energy source for
the body. Most polysaccharides are
eventually broken down to glucose by
our digestive system.
-- found naturally in green plants
-- chemical formula = (C6H12O6)
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Structure of Glucose:
OR

Each vertex in the above right drawing
represents a carbon ( C ) molecule (they are
numbered 1 to 6).
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B. Galactose – found in milk
-- possesses the same chemical
formula as glucose but has
one different arrangement of –H
and –OH on carbon #4.
C. Fructose – found in fruits
-- same formula as glucose, but a
much different –H, –OH, and C
arrangement.
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
Glucose, galactose, and fructose are all
structural ISOMERS of each other,
meaning that they each possess the same
chemical formula, but exhibit a different
arrangement of the atoms.
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Sugar Ray Leonard
After his first fight he ditched his
old nickname:
Monosaccharide Ray Leonard
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2. Disaccharides (Two Sugars):
-- formed when two monosaccharides
undergo DEHYDRATION SYNTHESIS
(producing a water molecule as well).
Three Major Types:
A. Maltose – Made up of two glucose
molecules (studied in Biology 12)
B. Sucrose – Made up of one glucose and
one fructose molecule
C. Lactose – Made up of one glucose and
one galactose molecule
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Maltose Formation by Dehydration
Synthesis
+
GLUCOSE
GLUCOSE
+H2O
MALTOSE
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Oxygen “Bridge”
Formula for Maltose: C12H22O11 – which is
equal to 2 x Glucose minus one water…
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The EMPIRICAL formula for carbohydrates is
CH2O.
However, a ‘carb’ made up of two glucose molecules
forms one water molecule during its construction.
Similarly, a “carb” made up of 50 glucose molecules
forms 49 water molecules.
To find the formula of any “carb,” all one needs to
know is either how many glucose molecules are
involved OR how many water molecules are formed.
Eg. A “carb” with 17 glucose molecules has a formula
of: 17 x (C6H12O6) – 16 x (H2O) = C102H172O86
So, the empirical formula is only a guide, it’s not exact.
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3. Polysaccharides (Long chains of sugars):
-- a POLYMER of monosaccharides.
-- three polysaccharides are common in living things (all are
polymers of glucose, but differ in their branching patterns):
A. Starch – storage form of glucose in
plants.
-- few side branches (very simple
arrangement)
-- the existing side branches all span
in the same direction
-- relatively straight molecule but adopts an
energy-efficient helical shape.
-- see figure 2.19 p. 33
-- easy to digest
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B. Glycogen – storage form of glucose in
animals.
-- more branched than starch (see
fig. 2.20 p. 33)
-- also easy to digest as the branching
allows digestion to occur at several
points simultaneously.
-- the liver converts excess glucose to
glycogen and stores it.
-- muscles also convert glucose to
glycogen and store it.
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C. Cellulose – the structural component of
plant cell walls.
-- possesses a much different type of
linkage between glucose molecules
(see fig. 2.21 p. 33).
-- humans are unable to digest
cellulose molecules; they pass right
through our digestive tract as fibre or
roughage.
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-- cows (and other ruminant animals)
are able to digest cellulose due to the
presence of symbiotic bacteria that exist in
their stomachs, bacteria which humans do
not house.
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I’ll RUN WILD on
you Atkins…eat your
CARBS, brother!!!
Damn, I’m lookin’ good!
Probably because of my
diet!
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