LIPIDS
Ryan Jeffery, Ali Loperena, Neil Jethani, Dee
White, Sammy Soliman, Nicolette Canale, Jon
Chernov, Keith Wright
OBJECTIVE B.4.1
Ryan Jeffery
WELCOME BACK!

It’s very nice to see you all again!

Now let’s get to work
OBJECTIVE 4.1

Assessment Statement


Compare the composition of the three types of lipids
found in the human body.
Teacher’s Notes

Examples include triglycerides (fats and oils),
phospholipids (lecithin), and steroids (cholesterol).
TRIGLYCERIDES
Fatty Acid Chains can very in length!
Chains are always EVENLY numbered in length!
COMPOSITION OF A TRIGLYCERIDE

Triglycerides have two parts
Glycerol
 Fatty Acids


Glycerol
Seen in Green
 3 Carbon atoms bonded to 3 Hydroxyl Groups


Fatty Acids
Carboxyl group
 Bonded to a hydrocarbon chain approximately 16 to
18 carbons long

EXAMPLES
Fat Molecules and Oils
 Both are found in abundance in fast food
 Both are linked to an increased risk of heart
disease and stroke.

PHOSPHOLIPIDS
Choline Group
Glycerol
Fatty Acid Chain
PHOSPHOLIPIDS

Make up most of the plasma membrane


PHOSPHOLIPID Bi-layer
First discovered in egg yolk by Theodore Nicolas
in 1847
LECITHIN

First phospholipid discovered


Specifically Phosphatidylcholine
Composed of:
Glycerophosphoric Acid (one saturated, one
unsaturated fatty acid)
 Choline Head


Found in:
Animal Tissue
 Plant Tissue
 Egg Yolks

STEROIDS*
STRUCTURE

20 Carbon Atoms

Form Four Rings
Three Cyclohexane rings (C6H12) (A,B,C)
 One Cyclopentane ring (C5H10) (D)
 Yes, that’s more than 20 C – They share

Varying functional groups
 Varying oxidation states

CHOLESTEROL
OBJECTIVE B.4.2
Ali Loperena
B.4.2 Outline the difference between HDL and LDL
cholesterol and outline its importance.
•
•
Cholesterol has a four ring structure
characteristic of all steroids.
The structure of cholesterol is called the steroid
backbone
•
•
Look for this in the hormones section and in the
medicines and drugs unit.
Cholesterol is transported around the body by
lipoproteins.
4.2 OUTLINE THE DIFFERENCE BETWEEN HDL
AND LDL CHOLESTEROL AND OUTLINE ITS
IMPORTANCE.
HDL
LDL
Full Name
High Density
Lipoproteins
Low Density
Lipoproteins
Approximate Size
8-11 nm
18-24 nm
•LDL transports cholesterol to the arteries where it
lines the walls. Atherosclerosis (thickened arteries) can
lead to cardiovascular disease.
•Major sources of LDL are saturated fats. In
particular those derived from lauric (C12 ), mystiric
(C14 ), and palmitic (C16 ).
•HDL can remove cholesterol from the arteries and
transport it back to the liver.
OBJECTIVE B.4.3
Neil Jethani
B.4.3 DESCRIBE THE DIFFERENCE IN
STRUCTURE BETWEEN SATURATED AND
UNSATURATED FATTY ACIDS.
SATURATED- carboxyl group connected to ONLY
single bonded C atoms bonded to H atoms. (C-C)
 UNSATURATED- carboxyl group connected to c
atoms with at least one group of double bonded C
atoms. (C=C)



The double bond causes fats (ex. triglyceerides) to have a
lower melting/boiling point-the double bond tends to keep
the fat flat-linear----usually oils at room temp
Steric effect (relevant to shape): the interjection of
double bonded C atoms prevent the fatty acid
molecules from approaching each other closely and
hence interacting via Van der Waals’ forces.
B.4.3 DESCRIBE THE DIFFERENCE IN
STRUCTURE BETWEEN SATURATED AND
UNSATURATED FATTY ACIDS.
Most naturally occurring fats and oils contain a
mixture of saturated, mono-unsaturated and
polyunsaturated fatty acids and are classified
according to the predominant type in the
mixture.
 Examples:


Unsaturated: Linseed soil (flax plant) has a low
percentage of saturated fatty acid.


Vegetable lipids are usually unsaturated
Saturated: Beef tallow (from beef fat) has a high
percentage of saturated fatty acids.

Animal lipids tend to be saturated
B.4.3 DESCRIBE THE DIFFERENCE IN
STRUCTURE BETWEEN SATURATED AND
UNSATURATED FATTY ACIDS.
SATURATED
UNSATURATED
B.4.3 DESCRIBE THE DIFFERENCE IN
STRUCTURE BETWEEN SATURATED AND
UNSATURATED FATTY ACIDS.
Summative Table
Type
Molec. Structure Phys. Structure
Van der Waals
Saturated
All single bonds
C-C
Greater (more
High (solid at
atoms)  stronger room temp)
interaction
Unsaturated
One C=C (mono-) Double-bonds
or several C=C
 kinked chain
(poly-)
Straight chains
Lesser (fewer
atoms)  weaker
interaction
Melting Points
Low (liquid at
room temp)
OBJECTIVE B.4.4
Dee White
B.4.4 COMPARE THE STRUCTURES OF THE TWO
ESSENTIAL FATTY ACIDS LINOLEIC (OMEGA–6
FATTY ACID) AND LINOLENIC (OMEGA–3 FATTY
ACID) AND STATE THEIR IMPORTANCE.
Linoleic (omega-6 fatty acid) Linolenic (omega-3 fatty acid)
 Poly-unsaturated fatty acid
 Poly-unsaturated fatty acid
 Carboxylic acid with an 18
 Carboxylic acid with an 18
carbon chain and two cis
carbon chain and three cis
double bonds (C=C)
double bonds (C=C)
 cis means on the same
 cis means on the same side
side
 The first double bond is located
 The first double bond is
at the third carbon from the
located at the sixth carbon
methyl end (aka- the omega
from the methyl end (aka- the
omega end) and the second is
end), the second is located at the
located at the ninth.
sixth, and the third is located at
the ninth.
omega end
omega end
Carboxylic Acid
Carboxylic Acid
Why so important?






Linoleic (omega-3 fatty acid) and Linolenic (omega-6 fatty acid)
are ESSENTIAL for human health.
We must have them in our diets because our metabolism cannot
synthesize them from food components.
A lack of omega-6 fatty acids causes dry hair, hair loss, and poor
wound healing.
Omega-3 fatty acids are thought to decrease the chances of
cardiovascular diseases and prostate cancer.
Both of these fatty acids are thought to help lower LDL
cholesterol.
Linoleic and linolenic are found in vegetable oils such as
sunflower oil, poppy seed oil, corn oil, and canola oil; as well as in
soybeans, hemp, and walnuts.
OBJECTIVE B.4.5
Ms M
B.4.5 DEFINE THE TERM IODINE NUMBER
AND CALCULATE THE NUMBER OF C=C
DOUBLE BONDS IN AN UNSATURATED
FAT/OIL USING ADDITION REACTIONS.
OBJECTIVE B.4.6
Sammy Soliman
B.4.6 DESCRIBE THE CONDENSATION OF
GLYCEROL AND THREE FATTY ACID
MOLECULES TO MAKE A TRIGLYCERIDE (2)

Glycerol:






3-carbon backbone
carbon 1 and 3 have two hydrogen and one hydroxyl
group attached
carbon 2 has one hydrogen and one hydroxyl group
attached
all bonds are covalent
the hydroxyl groups are polar allowing for dipole-dipole
interactions
Fatty Acid:


long carbon chain backbone
all bonds are covalent and non-polar
B.4.6 DESCRIBE THE CONDENSATION OF
GLYCEROL AND THREE FATTY ACID
MOLECULES TO MAKE A TRIGLYCERIDE (2)

Fatty Acid (continued):

two types:
Saturated – all single bonds (no more hydrogen atoms can
be accepted)
 Unsaturated – at least one or more double bonds between
carbon atoms (can accept at least or more hydrogen atoms
making it saturated)




Carbon 1 has a single bond with a hydroxyl group and a
double bond with an oxygen (carboxyl group)
Middle carbons have 2 hydrogen attached in saturated
fats and can vary between two, one, or no hydrogen
attached in unsaturated fats depending on the
placement of double bonds
End carbons have three hydrogen attached
B.4.6 DESCRIBE THE CONDENSATION OF
GLYCEROL AND THREE FATTY ACID MOLECULES
TO MAKE A TRIGLYCERIDE

Triglyceride:



(2)
Composed of three fatty acids attached to one glycerol
molecule via three separate ester bonds
Formed by a condensation reaction
Condensation Reaction:




Requires three fatty acids and one glycerol
The three fatty acids are bonded to the glycerol molecule
through a process known as esterification
The hydroxyl groups of the glycerol and the hydrogen in
the hydroxyl groups of the acids are lost during the
process
Each oxygen from the hydroxyl groups of the fatty acids
are then bonded to a separate carbon of the glycerol by
an ester bond forming a triglyceride
B.4.6 DESCRIBE THE CONDENSATION OF
GLYCEROL AND THREE FATTY ACID MOLECULES
TO MAKE A TRIGLYCERIDE

(2)
Condensation Reaction (continued):

The three hydroxyl groups and the three hydrogen
atoms that were lost form three water molecules (the
reason the reaction is called a condensation reaction)
B.4.6 DESCRIBE THE CONDENSATION OF
GLYCEROL AND THREE FATTY ACID
MOLECULES TO MAKE A TRIGLYCERIDE (2)
Hydroxyl
Group
Fatty
Acid Tail
Glycerol
Carboxyl Group
Ester bond
Triglyceride
B.4.6 DESCRIBE THE CONDENSATION OF
GLYCEROL AND THREE FATTY ACID
MOLECULES TO MAKE A TRIGLYCERIDE (2)

Condensation Reaction
OBJECTIVE B.4.7
Nicolette Canale
B.4.7 DESCRIBE THE ENZYME-CATALYSED
HYDROLYSIS OF TRIGLYCERIDES DURING
DIGESTION
Essentially the reverse of B.4.6
 During digestion
 Triglycerides broken down (hydrolyzed) by enzymes
(lipases)  glycerol and fatty acids
 In turn these are broken down by a series of redox
reactions  carbon dioxide, water, and energy

B.4.7
OBJECTIVE B.4.8
Jonathan Chernov
B.4.8 EXPLAIN THE HIGHER ENERGY VALUE
OF FATS AS COMPARED TO CARBOHYDRATES
(3)

Fats: Long hydrocarbon chains; most of the mass
in a fatty acid or triglyceride is from carbon, and
a small percentage is from oxygen


Carbohydrates: Contain equal proportions of
carbon and oxygen and twice as much hydrogen
atoms


Ex: C18H38O6
Ex: C6H12O6 (fructose)
When fats and carbohydrates are metabolized,
the main products are CO2 and H2O

The carbon and hydrogen form strong bonds with
oxygen which result in the large release of energy
B.4.8 EXPLAIN THE HIGHER ENERGY VALUE
OF FATS AS COMPARED TO CARBOHYDRATES

Reason: Amount of oxidation that takes place as the
compounds are converted to CO2 and H2O
Fats require more oxidation to be converted than
carbohydrates
 Carbohydrates have one oxygen atom for every carbon
atom, so each carbon atom needs only one more oxygen and
each pair of hydrogen atoms need one more oxygen



In fats most carbons are bonded to hydrogen atoms, so
when fats are metabolized they form more new C-O bonds,
releasing more energy than carbohydrates



Carbohydrates make fewer C-O bonds because the bonds
already exist
Each carbon atom needs two oxygen atoms instead of one,
while each hydrogen needs one oxygen
The bond enthalpy of the C-O bond is high, so when it
forms a large amount of energy is released
Fat molecules require about half as much oxygen for
the same number of carbon atoms

Oxidation of fats is longer, but produces more energy
B.4.8 EXPLAIN THE HIGHER ENERGY
VALUE OF FATS AS COMPARED TO
CARBOHYDRATES

When comparing fats and carbohydrates gram to
gram:
More oxygen is included in the weight of a
carbohydrate
 Fats have more carbon atoms per gram when
weighed, which means they will release about twice
as much energy as carbohydrates

Fats: 9 kilocalories/gram
 Carbohydrates: 4 kilocalories/gram

B.4.8 EXPLAIN THE HIGHER ENERGY
VALUE OF FATS AS COMPARED TO
CARBOHYDRATES

Examples of metabolization reactions:
Fat: O2 + C58H112O6  CO2 + H2O + energy
 Carbohydrate: C6H12O6 + 6 O2  6 CO2 + 6 H2O +
energy

OBJECTIVE B.4.9
Keith Wright
OBJECTIVE B.4.9
Describe the important
roles of lipids in the
human body and the
negative effects that can
have on health.
MEMBRANES
Lipids compose the selectively-permeable
membranes required for diffusion.
 Phospholipids consist of a polar, hydrophilic
phosphate ‘head’ and two hydrophobic fatty acid
‘tails’.

MEMBRANES

The fact that one end of the phospholipid will
always point toward water and one will always
point away creates the structure of the
phospholipid bilayer.
ENERGY STORAGE
•
•
•
•
Triglyceride lipids are used to store energy.
Because the three hydrocarbon chains of a
triglyceride are hydrophobic, they remain stable
in the presence of less water.
Thus, lipids require only one-sixth the amount of
water to be activated that glycogen does.
When fully metabolised, one triglyceride yields
NADH, FADH2 and Acetyl CoA, which are used
in Cellular Respiration to produce 14 ATP.
STEROIDS
Steroid Hormones are cholesterol-based
molecules that are used in cell-signalling.
 Steroids consist of the cyclohexane rings and one
cyclopentane ring, to which various functional
groups are attatched.

STEROIDS
Steroids act by binding to surface proteins on the
cell membrane, or in the cytoplasm. The
hormone-protein complex enters the nucleus and
binds to a specific gene sequence, increasing or
decreasing the frequency of transcription.
 Video:
http://www.youtube.com/watch?v=oOj04WsU9ko

INSULATION
Lipids are natural insulators.
 Lipids are covalent compounds that do not
conduct heat or electricity easily.
 Lipid-filled cells called adipocytes found in the
subcutaneous layer of skin for an insular barrier
to help maintain body temperature.

HEALTH EFFECTS
Ω-3 FATTY ACIDS
Ω-3s are unsaturated hydrocarbon chains that
have a carbon double-bond from the third Carbon
down.
 Certain Ω-3s reduce the risk of heart disease by
increasing circulation and breaking down the
fibrin protein responsible for bloodclots.
 This clears the blood vessels and lightens the
heart’s workload, thus decreasing the risk of
heart attack and heart disease.

CHOLESTEROL & LDLS
Cholesterol is a steroid that is important for
biomolecular synthesis and membrane fluidity.
 LDL is a small lipoprotein containing cholesterol.
 A high-cholesterol diet can result in a high
concentration of LDLs in the bloodstream.
 These LDLs accumulate on the walls of arteries,
where they harden and obstruct bloodflow.

CHOLESTEROL & LDL
OBESITY
Obesity is the excess accumulation of body fat.
 Energy-rich carbohydrates and lipids from the
diet that are not metabolised are stored as lipids
in the adipocytes.
 Increased need for lipid storage leads to the
growth of more adipose tissue, increasing body
mass.

OBESITY
This increased body mass and weight puts strain
on the heart, joints, and skeleton, resulting in
increased risk of heart disease, arthritis, and
thrombosis.
 Increased lipid concentration hampers the
functioning of the liver, kidneys, and brain.

FATTY LIVER DISEASE
OTHER DISEASES
Gallstones
Osteoarthritis
Chronic Acid Reflux