ANSC 433 Lecture Notes - Lecture 8: Carboxylic Acid, Glycerophospholipid, Triglyceride
23 May 2018
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8. ANSC 433: Animal Nutrition & Metabolism Chantal Coutu
1
L I P I D S
Function of Carbohydrates
- Provide energy for normal maintenance and reproductive functions
- Source of essential fatty acids
- Carrier of fat-soluble vitamins
- Integral constituents of cell membranes
- Animals also store energy in fat since it does’t hold uh ater, i.e. ore eerg opat
Classification of Lipids
- Glycerol base = where we consider fats and oils
- Talk about glycolipids and phosphoglycerides to certain extent
- Talk about eicosanoids and steroids
• Not highly abundant in feed soures = h o’t disuss
any further (same goes for waxes)
Definition and Structure of Fatty Acids
- Fatty acids consist of a hydrocarbon chain with a carboxyl acid group at one end
- The general structure is RCOOH, where R is a carbon chain of variable length
Degree of Saturation
- Saturated chain each C atom has two hydrogen bonds
- Unsaturated one or more pair of C are attached by a double bond
- Important because this defines the chemical property of the FA
Configuration of Double Bonds
- Cis form when hydrogen atoms lie on the same side of the double bond
• Makes fold on itself
• Fold and turn in the opposite direction
- Trans form when hydrogen atoms like on the opposite side of the double bond
• Makes it more rigid and straight
• Made industrially through partial hydrogenation
Nomenclature of Fatty Acids
- Replace the final –e of the name of the parent hydrocarbon by the suffix -oic
- The position of the double bond is indicated by reference to:
• Delta () system: from the carboxyl carbon (carbon atom 1)
▪ Example: Linoleic acids (18:2 9,12)
▪ # carbons:# double bonds position of double bond
• Omega () system: terminal methyl as carbon 1 (the carbon)
▪ Example: Linoleic acids (18:2 n-6)
▪ N = count number of carbons from back end to double bond = indicate which carbon the double
bond is at, i.e. 18 – 6 = 9
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8. ANSC 433: Animal Nutrition & Metabolism Chantal Coutu
2
Fatty Acids most common in Animal and Plant Tissues
- Common names used to describe FA, came from historical use
or where isolated
• Should use chemical name whenever possible
- Table on right
Essential Fatty Acids
- Dietary essential fatty acids:
• Linoleic acid (18:2 n-6) or (C18:2)
• Alpha-linoleic acid (18:3 n-3) or (C18:3)
• Deficiency of these two: growth or reproduction failure, skin something
- Arachidonic acid (C20:4) is the metabolic essential fatty acids, but can be synthesized
- Functions of essential fatty acids:
• Integral components of cell membranes
• Precursors for eicosanoids
- Essential classification: Absence = impact growth or phenotype
Fatty Acids composition of common fats and oils
- Plant fats tend to contain unsaturated fats
- Table on right
Mono-, di- and triacylglycerols
- An ester is formed by the reaction of an alcohol with an organic
acid
- A monoglyceride, diglyceride and triglyceride would have the
following general structures
- Where R, R’ ad R represet three differet fatt aids
Triacylglycerol
- In stereochemical terms, the position occupied by the fatty acids are not identical
- Where R, R’ ad R’’ represet three differet fatt aids
- Simple when all three positions are occupied by the same fatty acid
- Mixed when the positions are occupied by more than one fatty acid
Glycolipids
- The lipids of grasses and clovers are predominantly galactolipids
- The fatty acids of the galactoside of grasses and clovers consists largely of linoleic and -
linolenic acids
- Rumen microorganism are able to break down the galactolipids to give galactose, fatty acids and
glycerol
• Cleave off glucose moiety and use as energy
- Have glucose moiety
- For nutritional purposes = in grasses as galactolipids
Phosphoglycerides
- Esters of glycerol in which only two of the alcohol groups are esterified by FA
• The third esterified by phosphoric acid
• The simplest phosphoglycerides = phosphatidic acid since it is the parent compound
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Document Summary
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