Dr. Tarek El Sewedy
Department of Medical Laboratory Technology
Faculty of Allied Medical Sciences
Lipids and Fatty acids
(1)
Intended Learning Outcomes
By the end of this lecture, students will learn:
 General structure and functions of lipids.
 How to write the chemical formula of fatty acids.
 Classification of fatty acids.
 Lipid Nutritional facts.
Lecture Content
• Lipids and fatty acids structure .
• Physiological role of fatty acids.
• Classification of lipids.
• Nomenclature of fatty acids.
• Classification of fatty acids.
• Fats and diet
Lipids
 Lipids are heterogeneous compounds composed of C,H and O and may
contain P, N and S.
 They includes fats, waxes, phospholipids, and other physical-properties
related compounds.
• They have the common physical property of being:
• Insoluble in water
• Soluble in nonpolar solvents such as ether and chloroform.
 The monomers of lipids are fatty acids.
Fatty acids
• Fatty Acids Are Key Constituents (Monomers) of Lipids
• Among the most biologically significant properties of lipids are their
hydrophobic properties.
• This property is mainly due to a particular component of lipids: fatty
acids
Structure of Fatty Acids
 Fatty acids are hydrocarbon chains of various
lengths and degrees of unsaturation that
terminate with carboxylic acid groups.
 a. Stearic acid (saturated)
 B. Oleic Acid (unsaturated)
 The physical characteristics of the fatty acid (e.g.
number of double bonds) determine its
biochemical properties (e.g. solubility, melting
point)

Fats containing a high proportion of saturated
fatty acids, such as butter , have a relatively high
melting temperature and tend to be solid at room
temperature.
 Most vegetable oils, which contain higher levels
of monounsaturated or polyunsaturated fats, are
usually liquid at room temperature.
Physiological role of fatty acids
• First, fatty acids are building blocks of phospholipids and glycolipids. These
molecules are important components of biological membranes.
• Second, many proteins are modified by the covalent attachment of fatty
acids, which targets them to membrane locations.
• Third, fatty acids are fuel molecules. They are oxidized to meet the energy
needs of a cell or organism.
• Fourth, fatty acid derivatives serve as hormones and intracellular
messengers.
Lipids & Energy
Carbohydrates = 4.1
Kcal/gm
Energy
source
Fat=9.3 Kcal/gm
1. Classification of lipids
1. Simple
2. Complex
3. Precursor or Derived
Classification of lipids
• LIPIDS ARE CLASSIFIED AS SIMPLE OR COMPLEX Or DERIVED
A. Simple lipids: Esters of fatty acids with various alcohols.
1. Fats: Esters of fatty acids with glycerol.
2.
Waxes: Esters of fatty acids with higher molecular weight alcohols.
(Fatty Acid)
A. Simple lipids
Esters of fatty acids with various alcohols.
(Fatty Acid)
O
H2C
OH
HC
OH
O
HO
H2C
C
OH
glycerol
fatty acid
H2C
O
C
O
R
HC
O
C
O
R
H2C
O
C
R
R
triacylglycerol
(Fat)
Ester Bond
(Simple Lipid) FAT
Triacylglycerol(Triglycerides)
Glycerol: Three carbon trialcohol.
 Fatty acids: aliphatic carboxylic
acids.
 Could be monoglycerides,
diglycerides, or triglycerides,
depending on whether there
are one, two, or three fatty acid
chains present in the molecules.
b. Complex lipids
• Esters of fatty acids containing groups in addition to an alcohol and a fatty acid.
• a. Phospholipids: Lipids containing, in addition to fatty acids and an alcohol, a
phosphoric acid residue.
• b. Glycolipids: Lipids containing a fatty acid, alcohol, and carbohydrate.
• C. Other complex lipids: Lipids such as sulfolipids and Lipoproteins.
Lipids in Cell Membrane
(Phospholipds)
1 glycerol + 2 fatty acids + 1 phosphate group + 1 organic functional group = phospholipid
Phosphate groups – Interacts with water; because the phosphate head is polar.
Fatty acid ‘legs’ – Non-polar, do not interact with water and align themselves together to be
protected from the water while exposing the phosphate groups to the water.
C. Derived lipids
• These include lipid-soluble vitamins, and hormones.
Nomenclature of Fatty Acids
•
The name for a fatty acid is derived from the name of its parent hydrocarbon
by the substitution of oic for the final e. ex. the C18 fatty acid is called
octadecanoic acid because the parent hydrocarbon is octadecane (18)
•
The notation 18:0 denotes a C18 fatty acid with no double bonds, whereas
(18:3n
9,12,15) signifies that there are three double bonds at position 9,12
and 15 of carboxyl carbon.
•
Carbon atoms are numbered from the carboxyl carbon (carbon No. 1). The
carbon atoms adjacent to the carboxyl carbon (Nos. 2, 3, and 4) are also
known as the α, β, and γ carbons, respectively, and the terminal methyl
carbon is known as the ω or n-carbon
I-According to number of carbon atoms
Short chain
2-10 C atoms
Butyric acid (4 C)
long chain
>10 C atoms
Palmitic acid(16C)
II-According to presence or absence of double bond
Saturated
unsaturated
Palmitic acid, Butyric acid,
Caproic acid, Stearic acid
Monounsaturated Polyunsaturated
Oleic acid C18
Nervonic acid C24
Linoleic acid C18
Linolenic acid C18
Arachidonic acid C20
SATURATED FATTY ACIDS
Common
Name
Condensed
Formula
Capric
CH3(CH2)8COOH
Lauric
CH3(CH2)10COOH
Myristic
CH3(CH2)12COOH
Palmitic
CH3(CH2)14COOH
Stearic
CH3(CH2)16COOH
Arachidic
CH3(CH2)18COOH
Common Unsaturated Fatty Acids
Common
Names
RCOOH
Formula
# of
Double
Bonds
Double Bond Position
Palmitoleic
C15H29COOH
1
9
Oleic
C17H33COOH
1
9
Linoleic
C17H33COOH
2
9, 12
Linolenic
C17H31COOH
3
9, 12, 15
Arachidonic
C19H31COOH
4
5, 8, 11, 14
Unsaturated fatty acid are classified into
Cis
trans
• Cis and trans are terms that refer to the arrangement of the two hydrogen
atoms bonded to the carbon atoms involved in a double bond. In
the cis arrangement, the hydrogens are on the same side of the double bond.
In the trans arrangement, the hydrogens are on opposite sides of the double
bond
III-According to nutrition state
Essential
Non essential
Polyunsaturated
Linoleic acid C18
Arachidonic acid C20
Sarurated FA
Monounsaturated FA
1-Non essential fatty acids:
They can be synthesized in the human body
All saturated and monounsaturated FA's
Ex: Palmitoleic acid ( 16:1n;∆9)
higher concentrations in the liver
Ex: Oleic acid; ( 18:1n;∆9)
majority of olive oil
CH3(CH2)5CH=CH(CH2)7COOH
2- Essential fatty acids
Polyunsaturated fatty acids
Need to get them from diet because the body cannot manufacture them.
Alpha linolenic acid (18:3n;∆9,12,15): is the so-called "parent" fatty acid for
the omega 3 family of fatty acids because the liver can make other omega 3
fatty acids from it.
linoleic acid (LA) (18:2n; ∆9,12);
Is the "parent" fatty acid for the synthesis of other omega 6 fatty acids in the liver. It is
found in the lipids of cell membrane. It is abundant in many vegetable oils, and
sunflower oils.
Arachidonic acid (20;4n;5,8,11,14)
Repair and Growth of skeletal muscle tissue
Abundant fatty acids in the brain
Play a central role in inflammation
‫*‬
‫تغريد محمود ابراهيم مصطفى‬
‫فدوى سعد محمد‬
‫(أعادة)‬
‫سهى هشام بدر عباس‬
‫أسماء محمد حسن‬
‫روزالين راوبين يعقوب فرج‬
‫فاطمة سعد محمد‬
‫أسراء محمد حافظ‬
‫هاجر عبد الشفيع‬
‫هدير السيد أحمد‬
‫عال حازم علي حسن‬
‫رحمه مسعد عبد اللطيف غنيم‬
‫أسراء كامل السيد‬
‫نهاد خالد عبد اللطيف‬
‫السيد مصطفى السيد‬
‫أحمد شفيق محمد‬
‫هند أحمد أبراهيم‬
‫نورهان اشرف السيد الشرنوبي خليفة‬
‫سهيله نبيل حامد عبد القادر‬
‫عبد الرحمن السيد علي‬
‫محمود رامي عقيلة‬
ASSIGNMENTS
• Selected students are requested to prepare slides about one of the
following topics (To be delivered before next lecture):
• Lipids and disease
• Healthy lipids
• Unhealthy lipids
• Atherosclerosis
• Saturated Fatty acids
• Unsaturated fatty acids
• Triglyceridss
Complete:
* -----------,--------------------and------------------are essential
fatty acids.
* ----------------and --------------are saturated fatty acids.
* All --------------and---------------are non essential amino acids.
* ----------------------- is the parent compound of
glycerophspholipids.
* Lipids includes three main classes which are-----,--------and-------
1-Essential amino acids are synthesized in human body.
2-Saturated fatty acids have one or more double bonds.
3-
Alpha linolenic acid is non-essential amino acid.
4- Palmitoleic acid is essential amino acid.
Principles of Biochemistry, Donald J. Voet, Judith
G. Voet, Charlotte W. pratt; Willey, 3rd ed.