3. Terms to be learned
• Triacylglycerol three fatty acids esterified to glycerol
• cis-C=C double bond; the hydrogens on each of the
two carbon atoms are on the same side of the C=C
plane (as opposed to trans-C=C bonds in which the
hydrogen atoms are on opposite sides)
• essential fatty acids; polyunsaturated fatty acids;
synthesized by plants but not by mammals
• fatty acid; unbranched hydrocarbon chain with a
carboxylic acid functional group at one end and acyl
group at the other end (CH3)
• Lipoprotein; protein with covalently attached lipids
Dr. Siham Gritly 3
4. • Bilayers; two lipid layers stacked so that the
hydrocarbon chains face each other, and the head
groups face out and interact with water
• Liposome lipid bilayers forming small vesicles in
aqueous solution
• Micelle aggregation of lipids in aqueous solution
• phospholipids (or glycerophospholipids) major
components of cell membrane; two fatty acids and
phosphoric acid esterified to glycerol
(CH2OH—CHOH—CH2OH)
• polyunsaturated (fatty acid) fatty acid containing
more than one C=C double bond
Dr. Siham Gritly 4
5. • saturated (fatty acid); fatty acid containing
no double bonds
• Amphipathic; a molecule that has a polar
region at one end location and a nonpolar
region at another
• Sphingolipids; complex lipids with
sphingosine, a C18 amino alcohol, as backbone;
found predominantly in nerve and brain tissue
Dr. Siham Gritly 5
6. Lipids
fats, oils, steriod and waxes
• Lipids are long hydrocarbon molecules
• Lipids are chemical compound naturally
occurring substance; consist of carbon, hydrogen,
and oxygen,
• widely found in plant and animal kingdoms.
• A molecule of dietary fat consists of several fatty
acids (containing long chains of carbon and
hydrogen atoms), bonded to a glycerol. They are
typically found as triglycerides (three fatty
acids attached to one glycerol backbone).
Dr. Siham Gritly 6
7. Classification of fats according to National
Academy of Sciences
• Total fat, provide 20-35 % of total energy intake
• Saturated fatty acids, risk of (Coronary Heart Disease
CHD) milk fat, coconut
• Cis monounsaturated fatty acids, (olive oil) prevent
(CHD), peanut oil
• Cis polyunsaturated fatty acids of two type health
benefit; fish oil, sunflower oil, corn oil, fish oil
• 1-Omega 6 fatty acids
• 2-Omega 3 fatty acids
• Trans fatty acids, risk of (CHD), margin, shortening
Dr. Siham Gritly 7
8. Common properties of lipids
• Insoluble in water; Most lipids are strictly nonpolar
and hydrophobic, so they dissolve in nonpolar
substances, such as ether, chloroform and benzene.
• Lipids are heterogeneous group of compounds related
more by their physical rather than by chemical
properties
• Lipids contain large regions of just carbon and
hydrogen, as carbon-carbon bonds and carbon-
hydrogen bonds
Dr. Siham Gritly 8
9. • Stored in adipose tissues (triacylglycerols)
• Related health problems such as obesity,
atherosclerosis
• the proportion of oxygen is low, so lipids are
mostly hydrocarbons
• The chemical structure of fats and oils, the most
common lipids, is based on fatty acid building
blocks and an alcohol, glycerol
• Fats are "hard" or solid at room temperature
• Oils are liquids at room temperature
Dr. Siham Gritly 9
10. major functions of lipids in human
body;
• They serve as structural components of biological
membranes, cellular constituents (lipoproteins)
• *main source of energy, provide the body with 2/3
of energy (9 kal) They provide energy reserves, in
the form of triacylglycerols
• *main source of fat soluble vitamins A, K, E D
• *protection against traumatic injury an shock
• *maintain body temperature
• Electrical insulator
Dr. Siham Gritly 10
11. Classification of lipids
• Simple lipids;-ester of fatty acid and alcohols
• 1-fats; ester of fatty acids with glycerol
• 2-waxes; ester of fatty acids with monohyri
alcohol
• Complex lipids;- ester of fatty acid containing
additional to alcohol and fatty acids other groups
• 1-phospholipids; containing phosphoric acid and
nitrogen containing bases such as
glycerophospholipid and sphingphospholipids
Dr. Siham Gritly 11
12. • 2-glycolipids; containing fatty acid,
sphingosine and carbohydrates
• 3-other complex lipid; lipoproteins
• Derived lipids;- include glycerol, steroid,
alcohol in addition to glycerol and sterols
Dr. Siham Gritly 12
13. Fatty Acids (FA)
• Fatty acids are long-chain hydrocarbon
molecules containing a carboxylic acid
• The numbering of carbons in fatty acids
begins with the carbon of the carboxylate
group.
Dr. Siham Gritly 13
14. Fatty acids structure
• Fatty acids consists of a carboxyl group
attached to a long hydrocarbon chain and
methyl group (CH3) at the other end
CH3(CH2)nCOOH
Dr. Siham Gritly 14
15. • Essential fatty acids and nonessential
• essential fatty acids; that they must be provided in the
diet.
• plants are capable of synthesizing linoleic and α-linolenic
acid, humans can acquire these fats by consuming a variety
of plants or else by eating the meat of animals that have
consumed these plant fats.
• These two essential fatty acids are also referred to as
omega fatty acids. The use of the Greek omega, ω, refers to
the end of the fatty acid opposite to that of the –COOH
group.
• Linoleic acid is an omega-6 PUFA and α-linolenic is an
omega-3 PUFA
Dr. Siham Gritly 15
16. The carbon chains of fatty acids can
vary in 3 ways
• 1-The number of carbons in the chain or the
Length of chain in fatty acid
• 4 – 22 carbons long
• Short chains are more soluble
• Short chains are more easily broken down
• Short chains oxidize more easily
Dr. Siham Gritly 16
17. • 2-Degree of saturation. The extent to which
the chain is saturated with hydrogen
• Saturated
• Monounsaturated
• Polyunsaturated
• Most plant fats are unsaturated,
• Fish oils are unsaturated
• Other animal fats tend to be saturated
Dr. Siham Gritly 17
18. • 3-The shape of the chain (straight or bent)
• The shape of carbon chain varies with
saturation
• Saturated and trans fatty acids have straight
carbon chain
Dr. Siham Gritly 18
19. Nomenclature of fatty acids
• 1-Fats may be classified as saturated or
unsaturated depending on the structure of the
fatty acids involved.
• 2-delta ∆ and omega ω systems
• 3-cis and trans geometric isomerisms
Dr. Siham Gritly 19
20. Saturated and unsaturated fatty acids
• Saturated acids end in; anoic
• Unsaturated fatty acid end in; enoic
• Saturated fatty acids; containing no double bond.
Based on acetic acid—CH3-COOH
where CH2 is added between methyl group and
carboxylic acid CH3-CH2-CH2------COOH
Eg. Stearic acid CH3(CH2)14COOH
Palmitic acid
Saturated fatty acids of less than eight carbon atoms are
liquid at physiological temperature
Dr. Siham Gritly 20
26. delta ∆ and omega ω systems
• Delta and omega systems are other
nomenclature of fatty acids
• The delta ∆ system the notation describe the
chain length and the number and position of the
double bonds
• The linoleic acid notation is 18:2 ∆9, 12
• This means 18 carbon in the chain, 2 double
bond at position 9 and 12
• In delta numbering start from the carboxyl end
of the fatty acid
Dr. Siham Gritly 26
27. delta ∆ and omega ω systems
α-Linolenic acid (ALA) 18:3Δ9,12,15 (no-3)
Essential fatty acid; An omega-3
polyunsaturated fatty acid
Arachidonic acid 20:4Δ5,8,11,14 An omega-
6 polyunsaturated fatty acid
Precursor for eicosanoid synthesis
Dr. Siham Gritly 27
28. • Omega system ω counts from the methyl end of
fatty acid hydrocarbon chain; the notation for
linoleic acid is 18:2 ω 6 or 18:2 n 6
• This means that carbon number of linoleic acid is
18 and 2 indicates the number of double bond in
position 6 counting from methyl group end of the
carbon chain
• The suggestion is that; The double bond in fatty
acid always separated by three carbon so if the
location of double bond of omega number one
known the other double bond will be known
Dr. Siham Gritly 28
30. Omega-3 (ω3) and omega-6 (ω6) fatty acids
• Omega-3 (ω3) and omega-6 (ω6) fatty acids
are unsaturated "Essential Fatty Acids" (EFAs)
that need to be included in the diet because the
human metabolism cannot create them from
other fatty acids
Alpha-linolenic acid is an omega-3 fatty acid
because it has a double bond three carbons
away from the "omega" carbon
Dr. Siham Gritly 30
31. Physiologically Relevant Fatty Acids
adapted from 1996–2012 themedicalbiochemistrypage.org, LLC |
info @ themedicalbiochemistrypage.org
Numerical
SymbolCommon Struture Comments
Name
Often found attached to the
Myristic acid
N-term. of plasma
membrane-associated
14:0
cytoplasmic proteins
Palmitic acid
End product of mammalian
fatty acid synthesis
16:0
Stearic
acid18:0
Dr. Siham Gritly 31
32. Physiologically Relevant Fatty Acids
adapted from 1996–2012 themedicalbiochemistrypage.org, LLC |
info @ themedicalbiochemistrypage.org
Oleic acid
An omega-9
monounsaturated fatty acid
18:1Δ9
Linoleic acid Essential fatty acid
An omega-6 polyunsaturated
18:2Δ9,12 fatty acid
Dr. Siham Gritly 32
33. Physiologically Relevant Fatty Acids
adapted from 1996–2012 themedicalbiochemistrypage.org, LLC | info @
themedicalbiochemistrypage.org
α-Linolenic
Essential fatty acid
acid (ALA)
An omega-3
polyunsaturated fatty acid
18:3Δ9,12,15
An omega-6 polyunsaturated
Arachidonic acid
fatty acid
Precursor for eicosanoid
20:4Δ5,8,11,14
synthesis
Eicosapentaenoi
An omega-3 polyunsaturated
c acid (EPA)
fatty acid
enriched in fish oils
20:5Δ5,8,11,14,17
Docosahexaenoi
An omega-3 polyunsaturated
c acid (DHA)
fatty acid
enriched in fish oils
22:6Δ4,7,10,13,16,19
Dr. Siham Gritly 33
35. Orientation of Cis and trans bond of
unsaturated fatty acids
• The steric geometry of unsaturated fatty acids can
also vary such that the acyl groups can be oriented on
the same side or on opposite sides of the double bond.
• A cis configuration; hydrogen atoms are on the same
side of the double bond. The more double bonds the
chain has in the cis configuration, the less flexibility
it has
• cis bonds limit the ability of fatty acids to be closely
packed, and therefore could affect the melting
temperature of the membrane or of the fat
Dr. Siham Gritly 35
36. • A trans configuration, means that the next two
hydrogen atoms are bound to opposite sides of
the double bond. As a result, they do not cause
the chain to bend much, and their shape is
similar to straight saturated fatty acids
Dr. Siham Gritly 36
37. Cis Configuration and
Trans Configuration
When the acyl groups are both on the same side of the double
bond it is referred to as a cis bond, such as is the case for oleic
acid (18:1).
When the acyl groups are on opposite sides the bond is
termed trans such as in elaidic acid, the trans isomer of oleic
acid
Cis Configuration Trans Configuration
Dr. Siham Gritly 37
38. Trans (Elaidic acid) the trans isomer of oleic acid
Elaidic acid is the principal trans unsaturated fatty acid
often found in partially hydrogenated vegetable oils
Dr. Siham Gritly 38
39. Cis Oleic acid
is a cis unsaturated fatty acid that has one double bond,
"bend or curve. it comprises 55–80% of olive oil
Dr. Siham Gritly 39
40. Glycerol C3H8O3
• Glycerol has three hydroxyl group attached to
each C atom ( alcohol) that are responsible
for its solubility in water
• The glycerol backbone is central to all lipids
known as triglycerides
Dr. Siham Gritly 40
41. Lipids and fats present in the body
in three different forms
• 1-neutral fats (triglycerides)
• 2-cholesterol (present only in animal origin)
• 3-phospholipids (largest lipid components in
the body)
Dr. Siham Gritly 41
42. 1-Triglycerides
• Triglycerides are the main dietary fats in
human body. It is a naturally occurring ester of
three fatty acids and glycerol that is the chief
constituent of fats and oils
• Triglycerides are alcohol glycerol (hydroxyl
group HO-) and three fatty acids (carboxyl
group COOH).
Dr. Siham Gritly 42
43. • In triglycerides, the hydroxyl groups of the
glycerol join the carboxyl groups of the fatty
acid to form ester bonds
• Ester bond a compound formed from an
alcohol and an acid by removal of water
Dr. Siham Gritly 43
44. Basic Structure of Triacylglycerides
Triglycerides consists of three fatty acids and
glycerol
Dr. Siham Gritly 44
45. • The main fatty acids ;
• 1-stearic acid a (saturated fatty acid)
• 2-oleic acid (unsaturated one double bond,
olive)
• 3-palmitic acid (saturated, poultry, beef, milk,
palm oil)
Dr. Siham Gritly 45
46. Lipids are stored as triacylglycerol in adipose tissues ,
three fatty acids are joined to glycerol by an ester
linkage
Dr. Siham Gritly 46
48. One molecule of the alcohol, glycerol Attached to the glycerol
(by dehydration synthesis) are 3 fatty acids. The fatty acids
determine the characteristics or properties of the fat. The bond
formed between the –OHs of the alcohol and the carboxyl
COOH of the fatty acid is an ester bond
Dr. Siham Gritly 48
49. 2-cholesterol
• *Are member of groups called sterols, it is
alcohol found only in tissues and cells of
animals' origin.
• Sterols (Steroids) are composed of
hydrocarbon chains with four interconnected
rings.
Dr. Siham Gritly 49
50. Cholesterol is a lipid (fat) which is produced by the
liver. Cholesterol is vital for normal body function.
Every cell in our body has cholesterol in its outer layer
Dr. Siham Gritly 50
51. • *main function of cholesterol;
• It enter in the formation of bile acids,
• *Essential component of the structural
membranes of all cells especially brain and nerve
cells
• *They form a part of certain enzymes
• *Enter in the formation of steroid hormones such
as esterogens, progesterone and testosterones
• *Enter in the formation of vitamin D.
Dr. Siham Gritly 51
52. The structure of sterols is very different from that of the long
carbon chains seen in fatty acids and phospholipids.
The carbons in the structure of sterol are mostly arranged in many
rings
Dr. Siham Gritly 52
54. 3-phospholipids
• *phospholipids are any lipids containing
phosphorus. they are the largest lipid
components of the body after triglycerides.
Most phospholipids additional to phosphate
containing choline
• *they form in all cells of the body
• *in plasma, they are present in combination
with proteins and lipoproteins, which evolved
in transport of fat and cholesterol
Dr. Siham Gritly 54
55. • *they form part of certain enzymes
• *main constituents of all cell membranes
• Phospholipids; a group called CHNOPS, or the
six elements of life:
• Carbon, Hydrogen, Nitrogen, Oxygen,
Phosphorus, Sulfur
Dr. Siham Gritly 55
56. The basic structure of phospolipids
phospholipids are similar to fats, except they contain a
phosphorous group and two fatty acids instead of three
Dr. Siham Gritly 56
57. Functions of phospholipids
• 1. Act as building blocks of the biological cell
membranes in almost all organisms, form the outer
cell membrane and help the cell maintain its internal
structures.
2. Participate in the transduction of biological signals
across the membrane.
3. Act as efficient store of energy as with
triglycerides.
.
Dr. Siham Gritly 57
58. • 4. Play an important role in the transport of fat
between gut and liver in mammalian digestion.
5. An important source of acetylcholine which
is the most commonly occurring
neurotransmitter substance Peripheral nervous
system (PNS) and central nervous systems
(CNS) occurring in mammals
Dr. Siham Gritly 58
59. Phospolipids; consisting of a water-soluble head and a fat-
soluble tail
Contain phosphorous Component of cell membranes Serve as
emulsifiers (allow fats and water to mix and travel in and out of
cells into watery fluid on both sides
Dr. Siham Gritly 59
60. example of phospholipids in the body
• -lecithin; neurotransmitter consist of glycerol, fatty
acids, phosphoric acid and cholin (nitrogen-containing
base). found in liver, egg yolk, soy beans. the main
function; transport and utilization of fatty acids with the
action of enzyme as well as it prevent mental
retardation.
• *cephalins; for blood clotting (thromboplastin)
• *sphingomyelins; nerve tissues and brain, function act
as insulator around the verve fibers, found in egg yolk,
liver.
• *glycolipids; serve tissues, cell membranes and help in
fat transport.
Dr. Siham Gritly 60
61. The structure of phospholipids is very similar to that
of triglycerides, except a fatty acid is replaced with a
compound that contains the mineral phosphorus and
often has nitrogen attached
Dr. Siham Gritly 61
62. The benefit of the phospholipid structure is that the
phosphate region makes the molecule highly amphipathic,
ideal for the cell membrane structure
Hydrophilic portion in the phosphate region
Hydrophobic portion in the fatty acid
Dr. Siham Gritly 62
63. Phospholipids are major component of all cell
membrane as they can form lipid bilayers. Most
phospholipids contain a diglyceride a phosphate group
and choline
Dr. Siham Gritly 63
68. • Lehninger. Principles of bochemistry. by Nelson and Cox, 5th
Edition; W.H. Freeman and Company
• Emsley, John (2011). Nature's Building Blocks: An A-Z Guide to the
Elements (New ed.). New York, NY: Oxford University Press. ISBN
978-0-19-960563-7.
• Koppenol, W. H. (2002). "Naming of New Elements (IUPAC
Recommendations 2002)" (PDF). Pure and Applied Chemistry 74
(5): 787–791. doi:10.1351/pac200274050787.
http://media.iupac.org/publications/pac/2002/pdf/7405x0787.pdf.
• What Are the Primary Functions of Phospholipids? | eHow.com
http://www.ehow.com/facts_7349125_primary-functions-
phospholipids_.html#ixzz2FzYc7HnG
Dr. Siham Gritly 68
69. • Campbell, Neil A.; Brad Williamson; Robin J. Heyden (2006). Biology: Exploring Life.
Boston, Massachusetts: Pearson Prentice Hall
• A. Burtis, Edward R. Ashwood, Norbert W. Tietz (2000), Tietz fundamentals of clinical
chemistry
• Maton, Anthea; Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna Quon
Warner, David LaHart, Jill D. Wright (1993). Human Biology and Health. Englewood Cliffs,
New Jersey, USA: Prentice Hall. pp. 52–59
• Maitland, Jr Jones (1998). Organic Chemistry. W W Norton & Co Inc (Np). p. 139. ISBN 0-
393-97378-6.
• Nelson DL, Cox MM (2005). Lehninger's Principles of Biochemistry (4th ed.). New York,
New York: W. H. Freeman and Company.
• Matthews, C. E.; K. E. Van Holde; K. G. Ahern (1999) Biochemistry. 3rd edition. Benjamin
Cummings.
• http://wiki.answers.com/Q/What_is_dehydration_synthesis#ixzz2BuiK645
Dr. Siham Gritly 69
