Chapter 14: Carbohydrates
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Simple Sugars have the formula Cn(H2O)n and
were once thought to be “hydrates” of Carbon.
The Carbon cycle.
____________
6CO2 + 6H2O + energy  C6H12O6 + 6O2
__________
Types of Carbohydrates



Monosaccharides – do not hydrolyze into smaller
units.
Disaccharides – consist of two mono units joined
together – these will hydrolyze (break apart).
Polysaccharides – consist of many mono units
and are sometimes called “complex
carbohydrates.”
Monosaccharides



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Have between three and eight C atoms.
Number of C’s determines whether it is a triose
(3), tetrose (4), pentose (5), hexose (6), etc.
All have at least two –OH groups and the term
polyhydroxy- is sometimes used.
Will have either an aldehyde or ketone group.
Aldehyde = aldose and ketone = ketose.
Molecules are written with the C backbone in a
vertical direction.
Monosaccharides

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Glyceraldehyde
Ketose or Aldose?
______________
O
H
C
H
C
OH
CH 2OH
Monosaccharides



Erythulose
Ketose or Aldose?
______________
CH 2OH
H
C
O
C
OH
CH 2OH
Monosaccharides and Chirality



Most monosaccharides have several chiral C’s.
If the lowest chiral C has the OH group on the
left, then it is called the L isomer. If it is on the
right, then it is called the D isomer.
Hint: C’s with double to the O are not chiral and
the -CH2OH groups are also not chiral.
Chiral Carbons

How many chiral carbons?
CH 2OH
O
H
C
H
C
OH
CH 2OH
H
C
O
C
OH
CH 2OH
Glucose


How many chiral
carbons? ___
Is this the D isomer?
H
O
C
H
C
OH
HO
C
H
H
C
OH
H
C
OH
____
CH 2OH
Fructose


How many chiral carbons?
___
Is this the D isomer? ____
CH2OH

C == O

HO — C — H

H — C — OH

H — C — OH

CH2OH
Some Important
MonoSaccharides
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Glucose, aka dextrose – the most important one.
D-glucose (p. 486) is oxidized in the body to produce
energy.
L-glucose (p. 488) cannot be oxidized.
D-galactose (p. 489) is an aldohexose and is obtained as
from disaccharides and is a close cousin of glucose.
D-fructose (p. 489) is a ketohexose and is twice as sweet
as sucrose. This is found in fruit juices and honey.
Cyclic Structures


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The structures of the mono
units are easy to show using
the vertical, open chain
system.
However, they actually
exist as five and sixmembered rings.
See also p. 492-3
Oxidation of Monosaccharides
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All aldoses like glucose and galactose can be
easily oxidized to yield carboxylic acids.
These are often referred to as “reducing sugars.”
Benedict’s reagent (Cu+2) is used to test for
glucose in the urine. The extent of a color
change indicates how much glucose is present in
the urine.
Disaccharides
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Composed of two mono units.
Some common ones are:
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Sucrose (Cane sugar) = Glucose + Fructose
Lactose (Milk sugar) = glucose + galactose
Maltose (Malt sugar) = glucose + glucose
In the presence of water and an acid catalyst,
these linked molecules will split apart back into
their mono units.
Sweetness Scale


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All sugars and sugar
substitutes vary in sweetness.
Sucrose is assigned a
sweetness of 100.
Some artificial sweeteners
have a caloric value, but
because they are many, many
times sweeter than regular
sugar they are used in much
smaller quantities.
Polysaccharides


This is essentially a polymer of glucose units (usually).
Plant Starch, like that found in potatoes and rice, exists
in two forms: Amylose and Amylopectin.

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Amylose is a long,continuous chain of glucose molecules.
Typically has 250 – 4000 units.
Amylopectin is a branched chain of glucose molecules.
Branches are about every 25 units.
See p. 487.
Animal Starch is also called ___________. This is
essentially a branched chain as well.

Branches are about every 10 – 15 units.
Amylose and Amylopectin
Polysaccharides

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____________, found in cell walls of plants and animals, is also a
long chain of glucose units much like amylose.
The linkage between each unit is different and is resistant to
hydrolysis.
Human’s do not possess the enzymes to break this material down for
energy as some animals do.
We often refer to this material in our diet as “fiber.”
Ch. 15 Lipids


Lipids are a family of compounds that are __________ in
water (ie. Non-polar).
Classes of Lipids:

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Waxes = fatty acid and long chain alcohol (ester)
Fats & Oils = glycerol + three fatty acids
Phospholipids = glycerol + 2 fatty acids + phosphate + an
amino alcohol
Sphingolipids = fatty acid + sphingosine + phosphate + an
amino alcohol
Glycolipids = fatty acid + glycerol or sphingosine + one
monosaccharide.
Steroids = a fused ring structure of three cyclohexanes and one
cyclopentane.
Fatty Acids



Long chain carboxylic acids.
12 – 18 Carbon’s are the most common.
Stearic acid is most often found in animal fat.
CH3CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2COOH
And it can also be represented like this:
O
C
OH
Fatty Acids


Can be saturated – all C-C single bonds.
Can be mono-unsaturated – one C-C double bond.
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Can be poly-unsaturated – more than one C-C double
bond.
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Ex) Oleic Acid found in olives and corn.
CH3(CH2)7CH=CH(CH2)7COOH
Ex) Linoleic Acid found in soybeans and sunflowers.
CH3(CH2)4CH=CHCH2CH=CH(CH2)4COOH
In the Unsaturated acids, the cis isomer is usually found.
Common ones shown on p. 499.
Physical Properties


The repeating zig-zag shape of saturated fatty
acids allows them to fit close together leading to
strong attractions. As a result, these are solids at
room temperature.
The unsaturated fatty acids do not stack together
because of the double bonds. As a result, these
are liquids at room temperature.
Physical Properties
OH
C
O
OH
C
O
C
O
OH
Physical Properties
O
C
OH
O
C
OH
O
C
OH
Waxes


A wax is an ester of a fatty acid plus a long chain
alcohol.
The reaction for Beeswax is:
O
CH3(CH2)14 C
O
OH + HO (CH2)29CH3
CH3(CH2)14
C
O
(CH2)29 CH 3
+ H2O
Fats and Oils
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Fats and oils are the most common lipids.
Often called triglycerides because they are a triester of glycerol and three fatty acids.
Tristearin consists of three stearic acid molecules
reacting with glycerol.
A Fat is a triglyceride that is ______ at room
temeprature. Source = animals.
An Oil is a triglyceride that is usually a ______
at room temperature. Source = plants.
Making a Fat


In Tri-Stearin, the “R” groups would be –(CH2)16CH3
Three water molecules are also produced.
Reactions of Fats and Oils

Unsaturated oils can be converted into saturated
ones by Hydrogenation. This reaction was
shown for the alkenes.
R

HC
CH
R
+ H2
R
H2C
CH2
Oxidation of Oils occurs with exposure to O2.
This occurs more easily at the C-C double
bonds. Thus, vegetable oils must have antioxidants added to retard this process.
R
Other Lipids

Phospholipids are found in the structure of cell
membranes.
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Sphingolipids are found in the brain and nerve
tissues.

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They regulate what passes into and out of cells.
They increase the speed of the nerve impulses as well
as form a protective coating over the nerves.
Glycolipids are also abundant in the brain and
nerve cells.
Steroids and Cholesterol

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Steroids are any
compounds containing
the steroid nucleus.
Cholesterol is the most
important and
abundant steroid in the
body.
You cannot exist with
out this substance!
Cholesterol
H3C
CH 3
CH 3
HO
CH 3
CH 3
The Importance of Cholesterol



All hormones have as their base structure the
steroid nucleus (pictured earlier).
Thus, the sex hormones and the adrenocortical
hormones depend on cholesterol for their
synthesis.
See molecules on p. 538 and you will see the
cholesterol structure contained in these
molecules.
Estrogen and Testosterone
CH 3
OH
CH 3
CH 3
HO
O
Estrogen
Testosterone
OH
Ch. 16 Amino Acids and Proteins
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
The human body produces over _________ different
proteins.
These are grouped together by their function. Some of
these are (Table 16.1):


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Structural – provide structural components. Examples are
Collagen found in tendons and cartilage and Keratin found in the
hair and skin.
Contractile – provides for the movement of muscles. Myosin and
Actin contract the muscle fibers.
Transport – carries essential substances through the body.
Hemoglobin transports oxygen to the cells.
Types of Proteins - continued
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Storage – provides for storage of nutrients. Casein
stores protein in milk and Ferritin stores iron in the
spleen and liver.
Hormone – helps regulate body metabolism. Insulin
regulates blood sugar levels.
Enzyme – catalyze biochemical reactions. Sucrase
catalyzes the hydrolysis of sucrose.
Protection – recognition and destruction of foreign
substances. Immunoglobulins stimulate the immune
response.
The Amino Acids
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Are the building blocks of
all proteins.
________ versions of
these.
All contain the carboxylic
acid and amine functional
groups.
Center C is called the
______ Carbon.
R
O
H
N
C
C
OH
H
H
The Amino Acids
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The R group is different for
all 20 amino acids.
The R group may be nonpolar like an H or a –CH3 or
polar or acidic or basic.
The alpha Carbon is also
chiral (except in Glycine).
All 20 are found on p. 556.
R
O
H
N
C
C
OH
H
H
Amino Acids
OH
CH3
H2N
C
H
O
CH2
C
OH
H2N
C
H
O
C
OH
•Alanine, on the left, is a non-polar amino acid.
•Serine, on the right, is a polar amino acid.
The Amino Acids

Because amino acids have both an acidic end and a basic
end, they may auto-ionize to form what is called a
zwitterion – the H+ is transferred from one end to the
other.
R
R
O
H
N
C
C
+
H
H
N
OH
H
H
H
O
C
C
O_
H
The Peptide Bond
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Amino acids link together by the reaction of a
carboxylic acid on one with the amine of another.
This is a condensation reaction similar to that of
the polyamides.
The linkage between the two is called a peptide
bond.
Reaction between Glycine and Alanine
H
O
H
CH 3
Heat
H2N
C
C
+
OH
H
H
H2N
C
H
H
O
C
C
H
N
CH 3
N
C
H
H
COOH
+ H2O
COOH
Primary Structure
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Chains of 3 – 50 amino acids are called polypeptides.
When more than 50 amino acids are joined, we usually
call it a protein.
For a polypeptide of only 5 amino acids, the number of
combinations possible is staggering (sort of like playing
the Lottery!).
The specific sequence of amino acids in a protein is
called the primary structure and is determined by our
____ code.
Our ___ codes for only a limited number of specific
sequences for making proteins.
Secondary Structure


Secondary Structure refers to how the amino acids next to
or near each other are arranged in space. Hydrogen
bonding (HB) forces within three or four nearby amino
acids are the most common type of interaction.
The three most common types of secondary structures
(p.542-3) are:



Alpha Helix - which is a corkscrew shape of the chain that results
from HB between every fourth amino acid. All of the R groups
then are pointed outward.
Beta-Pleated Sheet – rows of amino acids are held flat with HB
keeping them rigid.
Triple Helix – is three peptide chains woven together like a braid.
HB is also a powerful force that holds this together.
Alpha Helix Structure

Two models of the alpha helix:
Tertiary Structure


Tertiary Structure is the overall 3D shape of the
protein. This also involves Hydrogen Bonding
as well as cross-linking across much greater
distances.
Thus, you may get a hydrogen bond or cross-link
between one amino acid on the peptide and
another one that is hundreds of amino acids
away.
Tertiary Structure

A cross-link is
formed by the
oxidation of the
thiol group found in
the amino acid
Cysteine.
SH
CH2
H2N
C
H
O
C
OH
Tertiary Structure
The formation of the disulfide across a great
distance in the chain would like this.
 People with curly hair have many of these
cross linkages.

H
H
H
H
[O]
R
C
H
SH
+
HS
C
H
R
R
C
H
S
S
C
H
R
Tertiary Structure

Two types of tertiary structures:
 Globular proteins, like hemoglobin and insulin,
have a very compact and round shape. The nonpolar R groups point inward and the polar R
groups point outward and this makes these
proteins soluble in water.
 Fibrous proteins, like keratin (hair, skin), consist
of long, thin, fibrous shapes.
Albumin



A protein made in
the liver.
It is found in large
concentrations in
blood serum.
The pink portions
are alpha-helix and
the yellow portions
are beta-pleated
sheet sections.
Quaternary Structure



Some proteins consist of two
or more sub-units (tertiary
structures).
The overall protein structure is
then referred to a quaternary
structure.
Hemoglobin consists of four
heme units – each unit being
able to transport one O2
molecule.
Overview of Protein Structures
Overview of Protein Structures