Lipids chem Flashcards
LIPIDS: BIOLOGICAL FUNCTION 9
Storage of Energy, Insulation from environment, Water Repellant, Buoyancy control and acoustics in marine mammals, Membrane Structure, Cofactors for Enzymes, Signaling molecules, Pigments, Antioxidants
Classification Lipids 7
Fatty Acids, Waxes, Triglycerides, Phospholipids and Glycolipids, Steroids, Ecosanoids, Membranes
Eight Major Categories of Biological Lipids
Fatty Acids, Glycerolipids, Glycerophospholipids, Spingolipids, Sterol Lipids, Prenol lipids, Saccharolipids, Polyketides
2 major categories based on structure and function:
Lipids that contain fatty acids (Complex lipids)
Lipids that do not contain fatty acids
Two major categories based on their reaction thru
saponification:
Saponifiable lipids
Nonsaponifiable lipids
Saponifiable lipids types 2
Simple lipids
Complex lipids
are the building blocks of many lipids.
Fatty Acid
Saturated Fatty Acid General Formula
CH3(CH2 )nCOOH
Necessary for specific biochemical functions and
must be supplied in the diet.
Essential fatty acids
Two nomenclature systems are used to identify the
length and double bond in the fatty acid
Delta Numbering, Omega Numbering
fatty acids that are essential nutrients
Omega-3 fatty acid
Two types of unsaturated fatty acids
Omega-3, Omega-6
Omega 3 Fatty Acid benefits in human body
reduce the risk of cardiovascular disease by
decreasing blood clot formation, blood triglyceride
levels, and growth of atherosclerotic plaque.
precursor for the synthesis of
prostacyclin, which inhibits clumpingof
platelets and thus reduces clot formation.
EPA
one of the major fatty acids in the
phospholipids of sperm and brain cells, as well
as in the retina; it has also been shown to
reduce triglyceride levels, although the
mechanism is not understood.
DHA
Seems to reduce the incidence of
cardiovascular disease, however it is not clear
whether it acts alone or because it is the
precursor of DHA and EPA
ALA
Also an essential fatty acid, required for the
synthesis of arachidonic acid,
Linoleic acid
are precursors of prostaglandins
that exhibit anti-inflammatory effects
Omega 3 FA
are precursors to prostaglandins
that have inflammatory effects.
Omega-6 FA
Decreases as the chain length increases.
Solubility
Decreases as the chain length decreases. Decreases as the number of double bonds increases.
Melting Point
Have straight –chain structures that allow
their molecules to fit close together and form
strong attractions.
Saturated FA
form by partial dehydrogenation of unsaturated fatty acids.
Trans fatty acids
Are esters composed of three fatty acids
joined to the trihydroxy alcohol, glycerol.
Triglycerides or triacylglycerols (TAG)
The advantage of fats over polysaccharides:
Fatty acids carry more energy, Fatty acids carry less water
if the reacting fatty acid molecules are not all identical,
Mixed Triacylglycerol
is a triester formed from
the esterification of glycerol with three identical
fatty acid molecules.
Simple Triacylglycerol
Current recommended amounts are: total fat
intake in calories:
- Monounsaturated fat
- Polyunsaturated
- Saturated fats
15%
10%
< 10%
Bad Fats vs. Good fats
o Saturated fats
o Monounsaturated fats
o Trans-monounsaturated fats
o Polyunsaturated fats
o Omega 3 and 6 are important “good fats”
= “bad fats”
= “good fats”
= “bad fats”
= both good and bad
= are important “good fats”
Heart SatFat Graph
Canola Oil
Safflower Oil
Sunflower Oil
Corn Oil
Olive Oil
Soybean Oil
Margarine, tub*
Peanut Oil
Margarine, stick*
No heart SatFat Graph
Cottonseed Oil
Solid Vegetable shortening
Lard
Palm Oil
Butter
Palm Kernel Oil
Coconut Oil
Physical Properties of Tags:
Pure fats and oils are….
colorless, tasteless, and odorless.
The characteristic colors, odors, and flavors
associated with lipids are imparted to them by
foreign substances
They are poor conductors of heat and electricity and therefore, serves as _______
excellent insulators for the body.
CHEMICAL PROPERTIES OF TAGs 5
Hydrogenation
Halogenation
Hydrolysis
Oxidation
Saponification
Addition of H2 to double bonds of unsaturated fatty acids in lipids, converting them to single bonds of saturated fatty acids.
HYDROGENATION
Complete hydrogenation gives a __________,
whereas the partial hydrogenation of a liquid vegetable
oil changes it to a _____________.
very brittle product; soft, semisolid fat.
Addition of water to ester bonds of lipids in
the presence of strong acids or digestive
enzymes called ________
Lipases; HYDROLYSIS
Addition of halogen across double (=) bond, this increases degree of saturation
- A test for unsaturation
HALOGENATION
Reaction of lipids with a strong base (alkaline hydrolysis) to give glycerol and salts of the fatty acids (called _____).
SAPONIFICATION; soaps
Products of the reaction are (Saponification)
- An alcohol
- An ionized salt which is a soap.
- Soaps have a long uncharged hydrocarbon tail
- Also have a negatively charged carboxylate group at end.
- Form micelles that dissolve oil and dirt particle.
The salts of fatty acids are also called _____,
and are considered ______. meaning they
have a part that is _______ along with
a part that is __________.
Soaps; amphipathic; very hydrophobic; very hydrophilic
They do not form insoluble products with hard
water.
Detergents
Double bonds in triacylglycerols are subject to
oxidation with oxygen in air (an oxidizing agent)
-Leads to C=C breakage
OXIDATION
Fat and oil develops a disagreeable odor caused by hydrolysis and oxidation.
Rancidity
Under moist and warm conditions, hydrolysis of the ester linkages occurs, liberating the volatile acids (butyric or caproic acids). Microorganisms present in the air furnish the enzyme (lipases) that catalyze the process.
Hydrolytic rancidity
Occurs in triglycerides containing unsaturated fatty acid
Oxidative rancidity
Are compounds added to foods in very small amounts (0.01–0.001%) to suppress rancidity. They have a greater affinity for oxygen than the lipid to which they are added and thus function by preferentially depleting the supply of adsorbed oxygen. Some naturally occurring
antioxidants used in the food industry are _____, ______, ________
Antioxidants; BHT, BHA, Vitamin E