PHAROS UNIVERSITY FACULTY OF ALLIED MEDICAL SCIENCE

BIOCHEMISTRY 1 (MGBC-201)

Dr. Tarek El Sewedy

Department of Medical Laboratory Technology

Faculty of Allied Medical Sciences

Lecture

Lipids and Fatty acids(1)

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.

Intended Learning Outcomes

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.

Carbohydrates = 4.1 Kcal/gm

Fat=9.3 Kcal/gm

Energy source

Lipids & Energy

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)

g ly c e ro l fa tty a c id tr ia c y lg ly c e ro l

H 2 C

HC

H 2 C

OH

OH

OH

H 2 C

HC

H 2 C

O

O

O

C R

O

C

C R

OR

O

HO C R

O

Esters of fatty acids with various alcohols.

A. Simple lipids

(Fatty Acid)

(Fat)

Ester Bond

(Simple Lipid) FAT

Triacylglycerol(Triglycerides)Glycerol: Three carbon tri-

alcohol.

Could be monoglycerides,

diglycerides, or triglycerides,

depending on whether there

are one, two, or three fatty acid

chains present in the molecules.

Fatty acids: aliphatic carboxylic acids.

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 long chain2-10 C atoms >10 C atoms

Butyric acid (4 C) Palmitic acid(16C)

II-According to presence or absence of double bond

Saturated unsaturated

Monounsaturated Polyunsaturated

Palmitic acid, Butyric acid, Caproic acid, Stearic acid

Oleic acid C18Nervonic acid C24

Linoleic acid C18Linolenic acid C18

Arachidonic acid C20

SATURATED FATTY ACIDSCommon

NameCondensed

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 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

Common Unsaturated Fatty Acids

Unsaturated fatty acid are classified into

transCis

• 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

Sarurated FA Monounsaturated FA

Polyunsaturated

Linoleic acid C18

Arachidonic acid C20

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) CH3(CH2)5CH=CH(CH2)7COOH

higher concentrations in the liver

Ex: Oleic acid; ( 18:1n;∆9)

majority of olive oil

Need to get them from diet because the body cannot manufacture them.

2- Essential fatty acids Polyunsaturated fatty acids

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

* Students selected for assignment محمد سعد فدوى

حسن محمد أسماء

محمد سعد فاطمة

الشفيع عبد هاجر

أحمد السيد هدير

اللطيف عبد خالد نهاد

السيد مصطفى السيد

محمد شفيق أحمد

أبراهيم أحمد هند

علي السيد الرحمن عبد

عقيلة رامي محمود

مصطفى ابراهيم محمود تغريد

) أعادة)

عباس بدر هشام سهى

فرج يعقوب راوبين روزالين

حافظ محمد أسراء

حسن علي حازم عال

غنيم اللطيف عبد مسعد رحمه

السيد كامل أسراء

خليفة الشرنوبي السيد اشرف نورهان

القادر عبد حامد نبيل سهيله

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

Study Questions

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--------

Correct the incorrect word:

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.

Suggested readings