Chapter 15
Lipids
SWBAT:
1. Describe a lipid
2. Describe the classes
of lipids
What are lipids?
Group of molecules not
defined by structure but by
common characteristics
They are:
• non-polar
• soluble in non-polar solvents like methylene
chloride, gasoline, ether
• not soluble in polar solvent like water
• fats, oils, fatty acids, waxes, steroids,
cholesterol, fat soluble vitamins
Lipids and Health
BMI: Body Mass Index:
Body Fat vs Obesity
Blood Lipids
CAD:
Coronary Artery Disease
Lipid deposits clogging arteries
in the body and heart
Risk Factors for CAD
• Hypertension, Diabetes, elevated cholesterol
• smoking
• sedentary lifestyle
• stress
• obesity
• male sex
• family history
• older age
Types of Lipids
Saponifiable Lipids:
• Prostaglandins
• Waxes
• Tricylglycerols
• Glycerophospholipids
Non-Saponifiable Lipids:
• Cholesterol
• Steroid hormones
Can be Hydrolyzed
Can NOT be
Hydrolyzed
Homework
Chapter 15.1
Pg 497
#15.2 – 15.4 (even)
Chapter 15
Fatty Acids
SWBAT:
1. Write structures of
fatty acids
2. ID saturated and
unsaturated fatty
acids
Fatty Acids
Contains a long carbon chain
attached to a carboxylic
acid on C1
Typically contain and even
number of carbon atoms –
between 10 and 20
Fatty Acids
They are:
• Aliphatic molecules – they
are both hydrophobic and
hydrophilic
• But…overall they are
hydrophobic
Hydrophobic Hydrophilic
Cell Membrane
Fatty Acids to know…
Lauric Acid (C12)
Myristic Acid (C14)
Palmitic Acid (C16)
Stearic Acid (C18)
Types of Fatty Acids
Saturated Fatty Acids:
• Only single bonds between
the carbon atoms
Monounsaturated Fatty Acids:
• Have one double bond in the
carbon chain
Polyunsaturated Fatty Acids:
• Have two or more double bonds
Unsaturated Fatty Acids
trans double bonds
cis double bonds
Shapes of Unsaturated
Fatty Acids
Fatty Acids:
Physical Properties
Saturated and trans Fatty Acids:
• High melting points (solids)
• Perfect alignment – high Van
de Waals intermolecular
attractions
• Trans fatty acids do not
naturally exist – they are
a man made product and
are the most stable fatty
acids
Fatty Acids:
Physical Properties
Unsaturated cis Fatty Acids:
• Lower melting point
(liquid at room temp)
• Do not have perfect
alignment due to kinks in
chain – low Van de Waals
• Less stable – double
bonds can break
Both are:
C18H36O2
Saturated
MP of 69°
Unsaturated
MP of 13°
Prostaglandins
They are:
• Small polyunsaturated Fatty
Acids that act like hormones
mediating a range of
symptoms from inflammation
to blood pressure
• Synthesized from
Arachidonic Acid (AA)
Prostaglandins
• Most have a hydroxyl group
on C11 and C15 and a trans
double bond at C13
• PGE - those with a ketone on C9
• PGF - those with a hydroxyl group on C9
Inflammation is a…
• Natural response to infection
and injury
• Disease like rheumatoid arthritis
(inflammation of the joints)
Why do we
care?
Non Steroidal AntiInflammatory Drugs
(NSAIDs)
Drug class that includes:
• Aspirin
• Ibuprofen
• Naproxen (Alveve)
• Ketoprofen (actron)
• Nabumetone (Relafen)
Long term use can result in
liver, kidney and
gastrointestinal damage
Video Links
NSAID effect and
side effect
Stomach side effect
Homework
Chapter 15.2
Pg 503
#15.6 – 15.18 (even)
Chapter 15
Waxes, Fats and Oils
SWBAT:
1. Write structural
formula of wax, fat or
oil
2. ID the reaction of a
fatty acid and an
Waxes
• Found in many plants and
animals (leaves, stems, skin,
fur and feathers)
• Is an ester of a saturated Fatty
Acid and a long-chain alcohol
(14-30 carbon atoms)
Fats and Oils:
Triacylglycerols
• The body stores Fatty Acids as
fats and oils
• Also called tryglycerides
• Produced by
esterification
of glycerol
and Fatty Acid
groups
Fats and Oils:
Triacylglycerols
Most fats and oils are mixed
triacylglycerolds with two or
three different Fatty Acids
from stearic acid
from palmitic acid
from myristic acid
can be saturated or unsaturated
Writing Structures for
Triacylglycerol
• Each Fatty Acid is attached by
an ester bond to one of the
hydroxyl groups in glycerol
Alcohol Part:
• In triglycerides
always glycerol
Carboxylic Acid Part:
• Three Fatty Acids
Fats and Oils:
Physical Properties
• A fat is a solid at room
temperature (fats in
meat, butter, cheese)
• There are exceptions
• Typically from an
animal source
• Oil is usually liquid at
room temperature (oils –
olive, peanut, sunflower)
• Typically from a plant
source
Fats and Oils:
Physical Properties
• Saturated Fatty Acids
have higher melting
points because they pack
together tightly
• Animal fats usually
contain more
saturated Fatty
Acids than
vegetable oils
Melting Points
Homework
Chapter 15.3
Pg 507-508
#15.20 – 15.28 (even)
Chapter 15
Chem Props of Triacylglycerols
SWBAT:
Draw the structure of the
product from a reaction
of triacylglycerol with
hydrogen, or an acid or
base
Hydrogenation
• Hydrogenation of unsaturated
fats converts carbon-carbon
double bonds to single bonds
• Hydrogen gas is heated
through oil with a nickel catalyst
• Partial hydrogenation
changes oil to a soft,
semisolid fat (crisco)
H2
Why?
• Chemical process patented
in the 1940’s
• used to convert oil surpluses
from soybean farming
• into spreadable fats
(margarines) to alleviate butter
shortage
Problem…
Incomplete hydrogenation leads
to the formation of transdouble bonds→ Trans Fats
trans fats in our food
Video Link
Trans Fats raise LDL (bad cholesterol ) levels in
the body
Consumption of Trans Fats is correlated with a rise
in CAD during 1960-2000
FDA prohibits use of Trans Fats & requires labeling
Hydrolysis
• Breaking the ester bond –
yielding fatty acid & glycerol
• First step in the digesting of
triglycerides in the body
• Carried out by the enzyme lipase
H+
lipase
• Glycerol is
soluble in
water
• Fatty
Acids are
not
Saponification (sapon = soap)
• Reacting triglycerides with a
strong base
• Yields glycerol and Fatty Acid
Salts (soap)
Glycerol tritearate + 3 NaOH
glycerol + 3 sodium stearate
What is Soap
• Soaps are aliphaic molecules
that have a polar part (facing
water molecules) and a nonpolar part (facing greasy dirt)
• Ancient soap making – Animal fats are
heated with a strong base (lye from burnt
limestone)
• Fatty acid salts – Sodium paltmitate:
Na+ -OOC-(CH2)14-CH3
• Soap Making Video
Food Labels
Food Labels
Olestra
• Fatty Acids from cottonseed
or soybean oils
• Composed of 6 to 8 longchain Fatty Acids attached to
sucrose rather than glycerol
• We can’t digest it
so “Fake Fat” goes
straight through
our system
• GI problems
occurred 
Homework
Chapter 15.4
Pg 512-513
#15.30 – 15.36 (even)
Chapter 15
15.5 Glycerophospholipids
SWBAT:
1. Describe the
characteristics of
glycerophospholipids
What are
Glycerophospholipids?
• Similar to triglycerides except
one hydroxyl group is replaced
by the ester of phosphoric acid
and an amino alcohol
• Bonded through a phosphodiester bond
Triglycerides
Glycerophospholipids
Amino Alcohols
• Three amino
alcohols found in
glycerophospholipids
are:
choline
ethanolamine
serine
Lecithins
• Lecithins contain choline
• Fatty Acids can be same,
different, saturated,
unsaturated or mixture
• Abundant in:
• brain tissue
• nerve tissue
• egg yolks
• wheat germ
• yeast
Cephalins
• Cephalins contain
ethanolamine and
sometimes serine
• Abundant in:
• brain tissue
• nerve tissue
• egg yolks
• wheat germ
• yeast
Polar?
• Hydrophobic
Tails
• Hydrophilic
Head Group
• Contain both polar and nonpolar regions
• Ionized alcohol and phosphate portion is
called “the head”
– Can hydrogen bond with water
• Two Fatty Acids represent “the tail”
Polar and Nonpolar
Regions
• Most abundant in lipids in
cell membrane
Polar Head
Nonpolar Tails
Homework
Chapter 15.5
Pg 515
#15.38 – 15.42
Chapter 15
Cholesterol & Steroid Hoemones
SWBAT:
Describe the
structure of steroids
General Structure
Steroidnucleus:
• Three cyclohexane rings A,B,C
• One cyclopentane ring D
Types of Steroids
•
•
•
•
Cholesterol
Lipoproteins
Steroid Hormones
Anabolic Steroids
Cholesterol
Most abundant steroid
in the body
• Why does it
have the
ending –ol?
Facts about Cholesterol
•
•
•
•
•
its part of every cell membrane
insulates nerve and brain tissue
forms bile for digestion
forms Vitamin D in skin
starting material for steroid hormones: sex
hormones, cortisone
• leads to heart attacks
Lipid Metabolism
• Cholesterol is so important
that the body does not rely
on what you eat….
• It manufactures 80% of the
cholesterol needed
• Serum Cholesterol Levels in your body can
be measured via blood tests: Lipid Panels
Lipid Panels
What health care
professional look for…
• Total Cholesterol
• HDL: High density Cholesterol – “good”
• LDL: Low density Cholesterol – “bad”
Why?
Lowering Cholesterol Levels is
a business….
Food industry:
fat free/cholesterol free items
lean meats
low fat dairy
hunt against saturated fats
Pharmaceutical industry:
statin drugs
HMG-CoA reductase inhibitors
LIPITOR
The most widely used drug in
the world…
• Pharmaceutical drug lowering
cholesterol levels
• Reaps 26 billion in sales
per year worldwide
• Side effects range from
diabetes, to cancer
Cholesterol Levels
Cholesterol levels show
individual variations due to:
• Genetics
• Age
• General health: cholesterol is an antiinflammatory, anti-stress substance, it can
rise due to reasons ranging from stress,
lack of sleep, drugs and chronic diseases
(diabetes)
• Diet: Plant based diets are correlated with
lower cholesterol levels
Cholesterol in Food
•
•
•
•
•
Egg
Crab/Shrimp
Beef
White chicken
Fish
250 mg
150 mg
85 mg
75 mg
40 mg
• All animal based food
contain cholesterol
• All plant based foods
contain no cholesterol
Cholesterol and CAD
• Artheriosclerosis is the main cause of CAD
• It is caused by plaque that clog arteries
• Plaque are cholesterol deposits
Q: What makes cholesterol form plaque?
A: Inflammation
Transporting Fats in
Blood
• Lipids are insoluble in the
blood (=water)
• Lipids are transported from
spherical vesicles called
Lipoproteins
• Skin: Phospholipids,
Proteins
• Inside: Cholesterol,
Triglycerides
Steroid Hormones
Sex Hormones
• Estrogen: development of
female sex characteristics
• Testosterone: development of male sex
characteristics including muscle anabolism
• Progesterone: prepares uterus for
fertilized egg
Steroid Hormones
Corticosteroids
• Steroid Hormones produced
by the adrenal glands
• Natural – Cortisone
• Drug – Prednisone
• Helps with:
• stress response
• immune response
• regulation of
inflammation
Anabolic Steroids
• Synthetic Testosterone
derivatives
• Promote muscle growth,
reduce body fat
• Short term side effects:
broken bones, ruptured
tendons, kidney pain
• Long term use lead to
kidney, heart, liver damage
• Legal steroid Tren
Homework
Chapter 15.6
Pg 522
#15.44 – 15.54 (even)
Chapter 15
15.7 Cell Membranes
SWBAT:
1. Describe the
composition and
function of the lipid
bilayer in cell
membranes
Cell Membrane
• Composed of phospholipid
bilayer
• Polar head & nonpolar tails
• Semipermeable – items can
enter and leave
Lipid Bilayer
• Double row arrangement of
phospholipids
• Hydrophilic polar
heads align on
outer edges of
membrane
• Hydrophobic
nonpolar tails
move to center
Fluid Mosaic Model
• Lipid bilayer contains
unsaturated Fatty Acid
• Cis double bonds causes a
non-rigid structure
• In liquid like
bilayer:
• Proteins
• Carbohydrates
• Cholesterol
Homework
Chapter 15.7
Pg 524 – 525
#15.56 – 15.62