LIPIDS by Endang Astuti Chemistry Department Lipids can be considered to be biological molecules...
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LIPIDS by Endang AstutiChemistry Department
Lipids can be considered to be biological molecules which are soluble in organic solvents, such as chloroform/methanol and are sparingly soluble in aqueous) solutions.
Their are three major classes of lipids: TriglyseridesPhospholipidssteroids
Energy storage
• Fates stored in adipose tissue
Cell membrane structure
• Creates a barrier for the cell.
• Controls flow of materials.
Hormones and Vitamins
• Hormones-communication between cells.
• Vitamins-assist in the regulation of biological processes.
Lipid functions
1. Structure of fatty acids
Fatty acids have a long hydrocarbon chain with a terminal carboxylic acid group. Most of fatty acids have an even number of carbon atoms in an unbranched chain.
Saturated fatty acids have no-double bonds between the carbon atoms, whereas mono- and polyunsaturated fatty acids have one or more double bonds.
The properties of a fatty acid depend on the chain length and the number of double bonds.
Fatty acids are long unbranched chains of carbon atoms.
A carboxyl (-COOH) group at one end gives the molecule its acidic properties.
Most naturally occurring fatty acids contain an even number of carbon atoms in their backbone chains. Although a few with odd numbers are found in all organisms, these make up only a minor fraction of the total.
Stearic acid
Oleic acid
COMMON BIOLOGICAL SATURATED FATTY ACIDS
Symbol common name systematic name structure mp( )℃
12:0 Lauric acid dodecanoic acid CH3(CH2)10COOH 44.2
14:0 Myristic acid tetradecanoic acid CH3(CH2)12COOH 52.0
16:0 Palmitic acid Hexadecanoic acid CH3(CH2)14COOH 63.1
18:0 Stearic acid Octadecanoic acid CH3(CH2)16COOH 69.6
20:0 Arachidic aicd Eicosanoic acid CH3(CH2)18COOH 75.4
COMMON BIOLOGICAL UNSATURATED FATTY ACIDS
Symbol common name systematic name structure mp
16:1 9D Palmitoleic acidHexadecenoic acid CH3(CH2)5CH=CH-(CH2)7COOH -0.5
18:1 9D Oleic acid 9-Octadecenoic acid CH3(CH2)7CH=CH-(CH2)7COOH 13.4
18:2 9,12D Linoleic acid 9,12 -Octadecadienoic acid CH3(CH2)4(CH=CHCH2)2(CH2)6COOH -9
18:3 9,12,15D -a Linolenic acid9,12,15 -Octadecatrienoic acid
CH3CH2(CH=CHCH2)3(CH2)6COOH -17
Reaction of fatty acid
2. triglyceride Ester of glycerol and a fatty acid.Principal functions is energy storage-fat.
May have 1-3 fatty acids which can each be different.
1-monoglycerid 2-diglyceride 3-triglycerid
CHOH
CH2OH
CH2OH
+ (R1,R2,R3 ) C
O
OH CH
H2C
H2C
O
O
O C
C
C
O
O
OR2
R1
R3
+ 3H2O
Examples of triglyceride
Sucrose Polyester, SPE
Physical Properties of glyceride
Solubility Generally, triglycerides are completely nonpolar, with no affinity for water. But, since bi- or mono-glyceride consist of a polar or hydrophilic head and one or two nonpolar or hydrophobic tails , they are called amphiphilic and can be used as
emulsifier. Melting Point Depending on chain length and number of double bond .
1. Saponification
Chemical Properties of triglyceride
Saponification Number The number of milligrams of KOH required to saponify 1g of fat; an approximate measure of the average molecular weight of a fat.
2. Alcoholysis
H 2C O O C R
H 2C O O C R ''
H C O O C R '+ 3 C H 3O H
C H 2O H
C H 2O H
C H O HR (R ',R '')C O O C H 3+ ¼î ÐÔ ß»¯¼Á
3. hydrolysis
CHOH
CH2OH
CH2OH
+ (R1,R2,R3 ) C
O
OH CH
H2C
H2C
O
O
O C
C
C
O
O
OR2
R1
R3
+ 3H2O
4. Halogenation or hydrogenation
Iodine number
5. Rancidity
Acid number
3 Phosphoglycerides
Lipids that contain a phosphate group.
Modified fat
Phosphate replaces on fatty acid chain.
Uses
Production of cell membranes.
Emulsifying agents.
CH2OH
C
CH2OH
HHO
1
2
3
Á¢Ìå רһ±àºÅ
Stereospecific numbering
CH2OH
C
H2C
HHO
O P
O
O£
O£
Phospho-glycerol
H2C
C
H2C
HO
O P
O
O£
O£
O C
O
R1
C
O
R2
phosphatidic acid
H2C
C
H2C
HO
O P
O
O
O£
O C
O
R1
C
O
R2
X
Phosphoglycerides
Nonglycerol lipids
Sphingomyelin
Sphingolipids Example
Glycosphingolipids
4. sterols
12
34
56
7
89
10
1112
13
14 15
1617
Cyclopentane Phenanthrene Cyclopentanoperhydro-phenanthrene
Cholesterol
Cholesterol is a waxy, fat-like compound that belongs to a class of molecules called steroids. It's found in many foods, in your bloodstream and in all your body's cells. If you had a handful of cholesterol, it might feel like a soft, melted candle. Cholesterol is essential for: Formation and maintenance of cell membranes
(helps the cell to resist changes in temperature and protects and insulates nerve fibers)
Formation of sex hormones (progesterone, estradiol , testosterone)
Production of bile salts, which help to digest food Conversion into vitamin D in the skin when
exposed to sunlight.
Most of the body's cholesterol is manufactured in the liver.
• The formation of
cholesterol involves a
series of complicated
biochemical reactions
that begin with the
widespread 2-carbon
molecule Acetyl CoA.
• Cholesterol is made
primarily in your liver
(about 1,000 milligrams
a day), but it is also
created by cells lining
the small intestine and
by individual cells in the
body.
• When your doctor takes a blood test to measure your cholesterol level, the doctor is actually measuring the amount of circulating cholesterol in your blood, or your blood cholesterol level.
• About 85 percent of your blood cholesterol level is endogenous , which means it is produced by your body. The other 15 percent or so comes from an external source -- your diet.
• Your dietary cholesterol originates from meat, poultry, fish, seafood and dairy products. It's possible for some people to eat foods high in cholesterol and still have low blood cholesterol levels. Likewise, it's possible to eat foods low in cholesterol and have a high blood cholesterol level.
This coronary artery is becoming dangerously blocked as the cholesterol builds up.
Structure of cholesterol
12
34
56
7
89
10
1112
13
14 1516
17
H O
20 22
23
24
25
26 27
18
19
21
Phytosterols (dari tanaman)
12
34
56
7
89
10
1112
13
14 15
1617
HO
2022
23
24
18
19
21
12
34
56
7
89
10
1112
13
14 15
1617
HO
2022
23
24
18
19
21
Stigmasterol Glusterol
steroid
vitamin E (tocopherol) • As an anti-oxidant that assists in protecting cellular and
subcellular membranes in the body.• Helping the body's immune system. • May slow down premature aging by way of its protective
effects from free radicals caused by environmental factors. • May prevent cancer growth.• May lower blood sugar levels in diabetic patients• Inhibits platelet formation that are associated with
atherosclerosis.Only a relatively small amount of vitamin E is required to meet normal daily requirements. Fortunately, this amount is easily obtained from foods such as oill, many grains, nuts, and fruits, as well as fatty parts of meats.
5. Biomembrane
It must keep its molecules of life ( DNA , RNA ,
and its assortment of proteins ) from dissipating
away.
It must keep out foreign molecules that damage
or destroy the cells components and molecules.
Composition of biomembrane
Lipids phospholipids cholesterol Glycosphingolipids
Protein intrinsic protein extrinsic protein
Others saccharide and ions
Biological membranesCARBOHYDRATEEXTERIOR OF CELL
LIPID BILAYERPERIPHERAL PROTEIN
INTEGRAL PROTEIN
CYTOPLASM SIDE
The Fluid Mosaic Model
Lipid bilayers are fluid, and individual phospholipids diffuse rapidly throughout the two dimensional surface of the membrane; Membrane proteins diffuse throughout the membrane in the same fashion.
To "flip-flop" through the membrane to the opposite side is uncommon. To do so required the hydrophilic head of the phospholipid to pass fully through the highly hydrophobic interior of the membrane, and for the hydrophobic tails to be exposed to the aqueous environment.
The Fluid Mosaic Model
旋转侧向移动
摆动翻转
Factors Influencing Fluidity of Biological Membrane
the ratio of saturated to unsaturated
hydrocarbon chains of the
phospholipids;
level of cholesterol in the cell
membrane;
Other factors such as ionic strength,
polar group of phospholipids.
Membrane Transport Mechanisms
Simple Diffusion Diffusion is always down a concentration gradient. Facilitated DiffusionActive Transport Active transport requires the expenditure of energy.
The Na+-glucose Co-transporting Mechanism
Na+-K+-ATP酶
Epithelial Cells are Joined Together