The document provides an extensive overview of lipids, defining them as organic compounds that serve various biological functions including energy storage, cellular structure, and hormone production. It covers the classification of lipids, types of fatty acids, their properties, structures, and essential roles in the body, such as aiding digestion and protecting organs. Additionally, it discusses the significance of lipids in nutrition and metabolism, emphasizing their importance in a balanced diet.

3. Presentation
PRESENTATION TOPICS:
Lipids.
PRESENTED BY
Mishal Mehreen.

4. LIPIDS
Lipids
Definition:
Lipids are a heterogeneous group of organic compounds that are
insoluble in non polar organic solvent.
They naturally occur in most plants, animals, microorganismsand are
used as cell membrane components,. Energy storage molecules,
insulation,and hormones.
Lipids as hydrophobic compound,are components of cellular membranes.
Lipids are also used to store energy.

5. LIPIDS
Properties of Lipids:
• Lipids may be either liquids or non crystalline solids at room
temperature.
• Pure fats and oils are colorless, odorless and tasteless.
• They are energy rich organic molecules
• Insoluble in water
• Soluble in organic solvent like alcohol, chloroform, acetone,
benzene etc.
• No ionic charges
• Solid triglgcerols (Fats) have high proportions of saturated fatty
acids.
Liquid triglgcerols (Oils) have high proportions of unsaturated fatty acids.

6. FATTY ACIDS
Fatty Acids:
Fatty acids are the building blocks of the fat in our
bodies and in the food we eat. During digestion the body
breaks down fats into fatty acids, which can then be
absorbed into the blood. Fatty acids molecules are
usually joined together in groups of three, forming a
molecule called a triglyceride.

7. FATTY ACIDS
Fatty acids is the important component of lipids (fat-soluble
component of living cells) in plants, animals and microorganism.
Generally, a fatty acid consist of an even number of carbon
atoms, with hydrogen atom along the length of chain and
carboxyl group (-COOH) and the other end. It is that carboxyl
group that makes it an acid. If the carbon to carbon bonds are all
single, the acid is saturated. If any of the bond is a double or
triple, the acid is unsaturated and is more reactive. Fatty acids
are not found in free-state in nature. Commonly, they exist in
combination with glycerol in the form of triglyceride.

8. FATTY ACIDS
• Uses of fatty acids:
• Fatty Acids have a wide range of commercial applications.
• They are used not only in production of numerous food
products, but also in soaps, detergents and cosmetics.
• Soaps are the sodium and potassium salts for fatty acids.
• Some skin care product contain fatty acids which can help to
maintain healthy skin appearance and function.
• Fatty acids, particularly omega-3 fatty acids, are also commonly
sold as dietary supplements.

9. Classification of Fatty acids
Due to the fact that biosynthesis of fatty acids mainly occur with the
sequential addition of 2 carbon units fatty acids are divided into two types.
I.Even carbon fatty acids.
Most of the fatty acids natural lipids are of even
carbons, usaully ranges from 14C-20C. Even fatty acids, palmatic acids
(16C), stearic acid (18C) are most common.
II.Odd carbon fatty acids.
Odd chain fatty acids are found particularly
in ruminant fat and milk (e.g. heptadecanoic acid). Some plant-based fatty
acids, also have an odd number of carbon atoms. Amoung he odd chain
fatty acids, propionic acid (3C) and valeric acid (5C) are well known.

10. Due to the presence and absence of double bond fatty acids are divided into
two types.
I.Saturated fatty acids.
Saturated fatty acids do not contain double bonds.
Occurance and nature: The saturated fatty acids having
less than eight carbon atoms are liquid at room temperature
and are volatile.
Melting point: Melting point of saturated fatty acids
increases with the increase of carbon atoms, in fatty acid
chain.
II.Unsaturated fatty acids.
Unsaturated fatty acids contain double bonds.
Melting point: Melting point of unsaturated fatty acids increases
with the decrease in the number of double bond, in a fatty acid
chain.

11. Solubility: Solubility of fatty acids increase with the
increase of double bond and decrease with the decrease in
number of double bond.
Unsaturated fatty acids are further classified according to the degree of
there unsaturation.
i.Monounsaturated fatty acids.
ii.Polyunsaturated fatty acids.
I.Monounsaturated fatty acids.
Monosaturated fatty acids contain only one double bond.
They are found nearly in all fats.
For example, oliec acid CH3(CH2)7CH=CH(CH2)7COOH.
II.Poly unsaturated fatty acid.
Polyunsaturated fatty acids contain more than one double bond (DB).

12. Biologically three unsaturated fatty acids have importance i.e.
linoleic acid (2DB), linolenic acid (3DB) and Arachidonic acid (4DB).
Essential fatty acids: Polyunsaturated fatty acids, which are not
synthesized in the body, are known as “Essential fatty acids”.
Therefore these should be taken in the diet.
Presence: Oils cointain significant quality of polyunsaturated fatty
acids e.g. oil from corn, wheat germ, peanut, soya bean etc.
Lack of essential fatty acid can produce growth retardation and
other deficiency symptoms e.g. eczematous rash and
thrombocytopenia.

14. STRUCTURE OF LIPIDS
• Structure of lipids
Lipids are made of the elements Carbon, Hydrogen and Oxygen, but
have a much lower proportion of water than other molecules such as
carbohydrates. Unlike polysaccharides and proteins, lipids are not
polymers—they lack a repeating monomeric unit. They are made from two
molecules: Glycerol and Fatty Acid.
Lipids are an essential component of the cell membrane. The
structure is typically made of a glycerol backbone, 2 fatty acid tails
(hydrophobic), and a phosphate group (hydrophilic). As such, phospholipids
are amphipathicLipids are composed of a glycerol molecule bonded to long
hydrocarbon chain(s) (can be single or multiple) and, depending on the lipid,
to other molecules—such as a phosphate group (phospholipids).

15. STRUCTURE OF LIPIDS
Lipids consist of repeating units called fatty acids. Fatty
acids are organic compounds that have the general formula
CH3(CH2)nCOOH, where n usually ranges from 2 to 28 and is
always an even number. There are two types of fatty acids:
saturated fatty acids and unsaturated fatty acids.
The phosphate group is the negatively-charged polar head,
which is hydrophilic. The fatty acid chains are the uncharged,
nonpolar tails, which are hydrophobic. Since the tails are
hydrophobic, they face the inside, away from the water and meet
in the inner region of the membrane.

16. STRUCTURE OF LIPIDS
Hydrophilic structure :
Hydrophilic molecule or portion of a molecule is one whose
interactions with water and other polar substances are more
thermodynamically favorable than their interactions with oil or other
hydrophobic solvents. They are typically charge-polarized and
capable of hydrogen bonding.
Hydrophobic structure :
The hydrophobic interaction is mostly an entropic effect
originating from the disruption of the highly dynamic hydrogen
bonds between molecules of liquid water by the nonpolar solute
forming a clathrate-like structure around the non-polar molecules
“Hydrophobic literally means “the fear of water”. … The water
molecules then form more hydrogen bonds with themselves and the
nonpolar molecules clump together. The hydrophobic effect is
caused by nonpolar molecules clumping together”

17. CLASSIFICATION OF LIPIDS
• Classification of Lipids:
There is no internationally accepted system for the
classification of lipds. That is why they are classified variously
by various authors. Many lipids have ester linkages, which are
susceptible to saponification (formation of soap), which is a
common reaction of esters. Some complex lipids are non-ester,
and hence Non-saponifiable. Considering this difference lipid
compounds can be classified into two major categories:
i.Sponified Lipids.
ii.Non-Sponified Lipids.

18. CLASSIFICATION OF LIPIDS
Saponifiable Lipids
The lipids which consist of compounds whose molecules have one or
more groups that can hydrolyzed or saponified are called Saponifiable
lipids, e.g. Acylglycerols, Waxes, Phospholipids, Sphingolipids and
Glycolipids
1. Acylglycerols:
• Acylglycerols are composed of glycerol and fatty acids. The most
widely occurring acylglycerols is triacylglycerol, also called or neutral
lipids.
• Chemically, acylglycerols can be defined as esters of fatty acids and
alcohol. An ester is compound produced as a result of a chemical
reaction of an alcohol with an acid and a water molecule is released.

19. CLASSIFICATION OF LIPIDS

20. CLASSIFICATION OF LIPIDS
2. Waxes:
Waxes are esters of long chain alkanes long chain monohydric alcohols,
Ketones and long chain fatty acids. Waxes are solid with high melting
points. They are slippery to feel, harder and less soluble in common
solvents. The feathers of birds and fur of some animals have similar coating
which serve as a water repellent. Waxy coatings also prevent infection in
both plants and animals.
3. Phospholipids:
Phospholipids are the saponifiable lipids. They are derivatives of
phosphatidic acids, which is composed of glycerol, fatty acids and
phosphoric acid. Nitrogenous bases such as choline, ethanolamine and
serine are important components of phospholipids. When the esterifying
nitrogenous compound is choline base, the resulting phospholipids is called
Phosphatidyl Choline or Lecithins; but when it is ethanolamine. Some
cephalins contain the amino acids serine rather than ethanol amine, so they
are called Phosphatidyl serines.

21. CLASSIFICATION OF LIPIDS
4. Sphingolipids:
These lipids contain sphingosine instead of
glycerol as their backbone. Sphingosine is long chain aliphatic
amine to which a saturated fatty acids is attached through an
amide linkage and a phosphorylcholine group is attached to the
primary alcohol group. The sphingolipids are generally found in
animals. They were first isolated from brain and nervous.

22. CLASSIFICATION OF LIPIDS
Non-Saponifiable Lipids:
“The lipids which lack groups that can be
hydrolyzed or sponified are called non-sponifiable lipids.”
Carotenoids ( carotenes and xanthophylls ) and terpenoids (
terpenes and steroids ).
1. Carotenoids:
Carotenoids are lipids compounds that range
in color from yellow to orange. They are found nearly in all
higher plants. They are two kinds of carotenoids;

23. CLASSIFICATION OF LIPIDS
i. Carotenes:
These are pure
hydrocarbons ( C40 H56)
and are futher two types –
a- carotene and B-carotene.
ii. Xanthophyll:
These are oxygen
containg hydrocarbons
such as Lutein.

24. CLASSIFICATION OF LIPIDS
1.Terpene:
The terpenes include certain fat soluble vitamins such as
vitamin A,B and K.
2. Terpenoids:
Terpenoids are very large and important groups of
compounds which are made up of simple repeating units.

25. CLASSIFICATION OF LIPIDS
ii.Steroids
Steroids are high formula weight aliphatic compounds,
whose molecules are include the charactersristic of ring structure
called Steroids Nucleus.

26. STORAGE LIPIDS
• Storage Lipids:
Thoes Lipids that are stored in the Living bodies for energy
source are called storage Lipids.
The fats and oils used almost universally as stored form of
energy in living organisms are highly reduced compounds.
Lipids are such biomolecules that contain the highest
proportion of energy.
Not all but some lipids are used as energy.

27. STORAGE LIPIDS
• Fatty Acids
• Triacylglycerols
• Waxes
These are the storage Lipids.
Structure and detail of all these Lipids are discussed
earlier.

28. STORAGE LIPIDS
Fattyy Acids
Carboxylic Acids (COOH is C1)
Hydrocarbon tails (C4 – C36)
Saturated fatty acids N:0
Unaturated Fatty acids
Double bonds specified by (Δn)
Branches
Solubility
Longer chains
More hydrophobic, less soluble
Double bonds increase solubility
Melting points
Depend on chain length and saturation
Double bonds lead acyl chain disorder and low melting
temps
Unsaturated Fas are liquid at Room Temperature
TRIGLYCEROLS
• Glycerol head group HO-CH2-CH(OH)-CH2-
OH
• Ester linkage from each hydroxyl to Fatty
acid
• Carboxylate charge is lost
• TAGs more hydrophobic than FAS
• Energy source
• Concentrated source of energy
• Energy derived from oxidation reactions
• More completely reduced state yields 2x the
energy/g as Carbohydrates
• Pure non-aqueous phase
• Lipases hydrolize the ester linkages to
release Fatty Acids
• Vegetable Oils – unsaturated
• Catalytic hydrogenation reduces double
bonds
• Less specific than enzymatic methods
makes some trans-fats

29. STORAGE LIPIDS
WAXES
Esters of long chain fatty Acids with long chain
alcohols
Higher melting points
Hydrophobic

30. USES OF LIPIDS
USES OF LIPIDS IN HUMAN BODY
Lipids, also known as fats, play many important roles in our
body, from providing energy to producing hormones. You
wouldn’t be able to digest and absorb food properly without lipids.
Of course, eating more fat than you need can lead to weight gain,
but in proper amounts lipids are a healthy part of your diet.
Energy Production and Storage
The primary role of lipids in our body is to provide energy
for muscles and body processes.

31. USES OF LIPIDS
About half of the fuel
your body needs when at
rest or during everyday
activity comes from lipids.
Digestion and Absorption
Lipids in your body are essential for proper digestion and
absorption of food and nutrients.
Bile acids produced from lipids in your liver allow fat and water
to mix in your intestines and aid in the breakdown and absorption of
food.

32. USES OF LIPIDS
Insulation and Protection
Lipids are also used to insulate and protect your body. You have a layer of
fat just below your skin, than helps to keep your internal body temperature
regular despite the external temperature.
Cell Wall Structure:
The essential lipids, linoleic acid and linoleic acid, are vital to your health,
they cannot be made in your body and must come from your diet. These lipids
provide structure and support for the walls of every cell in your body.
Communication between cells is also dependent upon lipids in your cells
‘membranes.
Hormone Production
Cholesterol is a type of lipid needed to provide important steroid
hormones in your body.
Estrogen, testosterone, progesterone and the active form of vitamin are

33. USES OF LIPIDS
Absorption of Fats:
As muscles in your stomach churn
food, fats begin to break down, but digestion
of triglycerides and cholesterol doesn’t begin
in earnest until they leave your stomach and
enter your small intestine.
Entry into Bloodstream
Once inside the intestinal cells,
micelles go through another repackaging.
They’re now covered in a mixture of lipids
and proteins. This new coating allows facts to
travel through water-based environments in
your body.

34. USES OF LIPIDS
Fate of Circulating Fats
Once they’re in your bloodstream, lipoproteins have
different jobs. One type of lipoprotein carries fatty acids to tissues
that need them for energy, such as muscles.
Medium-Chain Triglycerides
Most of the fats in your diet consist of long-chain fatty
acids, which have 12 to 22 molecules of carbon. These facts are
digested like carbohydrates, which means they’re absorbed into
the small intestine and enter the blood stream. From there, they
travel to the liver, where they’re metabolized and used for energy.