Fatty Acids
description
Transcript of Fatty Acids
Fatty Acids
Long-chain carboxylic acids that have an even number (usually 12-18) of carbon atoms.
Insoluble in water. Saturated or unsaturated.
Fatty Acids
Fatty acids
Fatty Acid Formulas
The formulas for fatty acids are written as
condensed and line-bond formulas.
For example fatty acid with 8 carbon atoms can
be written as:
CH3—(CH2)6—COOH
CH3—CH2—CH2—CH2—CH2—CH2—CH2—COOH
O ||
CH3—CH2—CH2—CH2—CH2—CH2—CH2—C—OH
OH
O
General nomenclature The carbon atoms of an acid are numbered (or
lettered with Greek lettering system, such as α, β, γ) either from the carboxyl group or from the carbon farthest removed from the carboxyl group (n or omega numbering system)
CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-COOH10 9 8 7 6 5 4 3 2 11 2 3 4 5 6 7 8 9 10ω δ γ β α
Systematic names
Saturated F.As.Saturated fatty acids have single C–C bonds.
Saturated fatty acids have: Molecules that fit closely together
in a regular pattern. Strong attractions between fatty
acid chains. High melting points that makes
them solids at room temperature.
Saturated F.As.
Unsaturated fatty acids have cis C=C bonds.
Unsaturated F.As.
Unsaturated fatty acids typically contain cis double bonds.
Unsaturated F.As.
Unsaturated fatty acids: Have nonlinear chains that do not allow molecules
to pack closely. Have low melting points. Are liquids at room temperature.
Unsaturated F.As.
Olive Oil
Olive oil contains a high percentage of oleic acid.
Oleic acid is a monounsaturated fatty acid with one cis double bond.
In a triacylglycerol, glycerol forms ester bonds with three fatty acids.
Triacylglycerols
Hydrogenation of Oils
Hydrogenation: Adds hydrogen
to double bonds in oils to form single bonds.
Produces solid shortening, margarine, and other products.
Omega-6 and Omega-3 F.As.The first double bond: At carbon 6 (omega-6) (e.g. vegetable oils) At carbon 3 (omega-3) (e.g. fish oils)
Essential fatty acids Mammals cannot synthesize the two main types of
polyunsaturated fatty acids: the linoleic (omega-6) and linolenic (omega-3)
Essential fatty acid deficiency is characterized by dermatitis and poor wound healing
Most prostaglandins are synthesized from arachidonic acid (a linoleic acid derivative)
Lack of these prostaglandins causes some aspects of the essential fatty acid deficiency syndrome
Essential fatty acids A small daily intake of linolenic acid is
recommended (this may be especially important when the nervous system is developing)
Docosahexaenoic acid (22:6 3,6,9,12,15,18) is needed for maximum development of the visual and central nervous systems during the neonatal period (it is present in large amounts in the retina and parts of the brain; it enhances the visual response and the function of certain domains in neural membranes)
ProstaglandinsProstaglandins have: 20 carbon atoms in their fatty acid chains. An OH on carbon 11 and 15. A trans double bond at carbon 13.
Prostaglandins in the Body
Prostaglandins are: Produced by injured
tissues. Involved in pain, fever,
and inflammation. Not produced when anti-
inflammatory drugs such as aspirin inhibit their synthesis.
Other eicosanoids
When a cell responds to a stimulus, bioactive mediators (prostaglandins, thromboxanes, leukotrienes, and others) often are formed from the lipids contained in its membranes.
Thromboxanes regulate blood coagulation. Leukotrienes play a role in allergic and inflammation
responses. They were isolated from leukocytes (white blood cells).