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General formula for fatty acids
CnH2n+1COOH
When fatty acids are not attached to other molecules they are called
Free fatty acid
Why are fatty acids considered to be amphipathic compounds
They have a hydrophilic carboxylic group and hydrophobic aliphatic tail
Which part of fatty acid is hydrophilic?
COOH ; carboxylic group
Which part of the fatty acid is hydrophobic?
Aliphatic tail
What number (even / odd) straight chain fatty acids are found abundantly in plant and animals
Even number straight chains
Example of fatty acid with 16 carbons
Palmitic acid
Example of fatty acid with 18 carbon is
Stearic acid
What possess the ability to synthesize odd- and branched-chain fatty acids?
Bacteria
Why ruminant animal fat contains odd-numbered fatty acids(15)
Due to the action of bacterial in the rumen
What are saturated fatty acids?
Saturated fatty acids are fatty acids where there hydrocarbon chain contains no double bonds.
Butyric (n-butanoic) can be found in
Butter
Caproic (n-hexanoic) can be found in ?
Coconut
Palm oils
Caprylic (n-octanoic)
Coconut
Palm oil
Capric (n-decanoic)
Coconut
Palm oil
Lauric (n-dodecanoic)
Laurel oil
Spermaceti
Myristic (n-tetradecanoic)
Butter
Fats
Palmitic (n-hexadecanoic)
Palm tree
Animal
Plant fats
Stearic (n-octadecanoic)
Animal
Plant fats
Arachidic (n-eicosanoic) 20 carbons
Groundnut oil
Behenic (n-docosanoic)
Groundnut oil
Lignoceric (n-tetracosanoic)
Groundnut oil
Rapeseed oils
Cerotic (n-hexacosanoic)
Wool fat
What are unsaturated fatty acids?
Fatty acids that contain double bonds in there hydrocarbon chains
What is a unsaturated fatty acid with one carbon carbon double boned called?
Monoethanoid acids
What is an unsaturated fatty acid with two carbon carbon double boned called?
Diethanoid acids
What is an unsaturated fatty acid with three carbon carbon double boned called?
Triethanoid acid
What are essential fatty acid?
They are fatty acid the body is unable to synthesis but is necessary for the human diet. As it helps with memory, helps with skin, help to reduces cardiac problem and builds immunity
Where do fatty acids bend?
They bend at the carbon carbon double bond
Why are linoleic acid and linolenic acid considered essential fatty acids
Because they are unable to be synthesis by the body. The body contain the enzyme 4,5,6,9 desaturase meaning they are unable to form double bonds any other place other than carbon 4,5,6 and 9. In linoleic there is a carbon carbon double bond at carbon 12 which the enzyme is unable to form a double bond there. In linolenic acid there is a carbon carbon double bond at carbon 12 and carbon 15; where the enzyme is unable to form a bond there.
Linolenic acid is what type of omega acid?
Omega 3 fatty acid
Linoleic acid is what type of omega fatty acid
Omega 6 fatty acid
Many naturally occurring fatty acids contain
2-3 double bonds in the cis position
Why do carbon chain of saturated fatty acids tend to be fully extended?
To minimize the repulsion between neighboring methylene groups
What type of fatty acids are solid ?
Saturated fatty acids because they do not have any bend in there chain and are tightly packed together, hence having stronger Van der Waals attractions compared to unsaturated fatty acids
Why do unsaturated fatty acid have a lower melting and boiling point than saturated fatty acids?
Unsaturated fatty acids are not tightly packed together, they have double bonds in there chain that causes rigid bends in the chain that interferes with the packing causing weaker Van der Waals forces of attraction between molecules.
Unsaturated fatty acids appears as _____ at room temperature?
Liquid
Where are saturated fatty acid found?
In animals
Where are unsaturated fatty acid found?
In plants
Where are saturated fatty acids stored?
Liver
Bone
Where are unsaturated fatty acid stored?
Seed
Fruits
Effect of oxidative rancidity on saturated fatty acid
Observed less frequency
Effect of oxidative rancidity on unsaturated fatty acid
Observed more frequently
Fatty acids are important sources of ?
Fuel
When metabolized what do fatty acids yield?
Large quantities of ATP
What organs in the body does fatty acids fuel?
Heart
Skeletal muscle
Where are enzymes responsible for desaturating fatty acids found?
In the endoplasmic reticulum
How does desaturase enzyme work?
Adding cis double bonds
How is the body abl to convert Stearic acid to oleic acid
When the enzyme 4,5,6,9 desaturase inserts a double bond but is incapable of inserting further double bonds.
How can unsaturated fatty acids from vegetable oil have their double bond removed?
By adding hydrogen (Hydrogenation)
What are hydrogenated fat?
Saturated fat even though derived from vegetable oil.
What happens when unsaturated fatty acids react with gaseous hydrogen?
Forms saturated fatty acid
What reagent or agents are need for the hydrogenation of unsaturated fatty acids?
Hydrogen gas
Catalyst : nickel, Pt
What is partial hydrogenation?
When a little of hydrogen gas is used to convert some of the carbon carbon double bonds to single bonds but not all. The unsaturated bonds that remain that were normally in the cis position are changed to the trans position.
Partial hydrogenation forms what type of compounds?
Semi solid trans unsaturated compounds
Complete hydrogenation of unsaturated fatty acids forms what type of compounds?
Solid saturated compounds
What is hydrogenation of fatty acids used for?
Manufacture of:
Candles
Vegetable shortening
Margarines
Trans fat have what type of shape?
More linear shape
Why do trans fat have a linear shape?
Because trans compounds are able to interlock, hence are able to be tightly packed together.
Benefit of trans fat
Give products longer shelf life
Negative impact of trans fat
Raises bad cholesterol (low density lipoprotein)
Why is complete hydrogenation of fatty acid avoided?
Because saturated fatty acids are hard and brittle
What is halogenation of unsaturated fatty acid?
Halogens can be added to unsaturated fatty acids at room temperature
Oxidation of unsaturated fatty acid can form?
Two aldehyde
If unsaturated fatty acid is exposed to excess oxygen what is formed?
Two carboxylic acids
What happens to unsaturated fatty acid when comes in contact with KMnO4 under mild conditions?
The glycols are formed at the sites of double bonds
What happens to unsaturated fatty acid when comes in contact with KMnO4 under vigorous conditions?
The reagent cleaves the molecules at the double bond and oxidizes the terminal portions to the carboxyl groups.
Hence two carboxylic acids are made.
What is the oxidative rancidity of highly unsaturated oils?
Highly unsaturated oils are spontaneously oxidized by atmospheric oxygen and ordinary temperatures.
Example of an oil that is less susceptible to oxidative rancidity
Olive oil
Example of an oil that is more susceptible to oxidative rancidity
Flax seed oil
Is oxidative rancidity of fatty acids a slow or fast reaction
Slow reaction
Oxidative rancidity of unsaturated oils causes or forms?
Short chain fatty acids and aldehyde resulting in a rancid odor or taste to the fats.
Function of lipids
Store energy
Function of lipids
Acts as food storage
Are lipids soluble or insoluble?
Insoluble
Function of lipids
Membranes structure involvement
Function of lipids
High insulating capacity
Function of lipids(phospholipids)
Absorption and transport of fatty acids
Function of lipids (Cholesterol)
Play a role in hormone synthesis
Function of lipids (Vitamin A, D,E,K)
Carriers of fat soluble vitamins
Function of lipids (Squalamine - steroid found in sharks)
Antibiotic agent
Function of lipids
Aid to waterproof the body
Classification of Lipids
Simple lipids
Compound lipids
Derived lipids
Another name for simple lipids
Homolipids
Another name of compound lipids
Heterolipids
Example of homolipids
Triacylglycerol
Oils
Waxes
Example of heterolipids
Phospholipids
Glycolipids
What are derived lipids?
Lipids formed or derived from simple and compound lipids
Example of derived lipids
Steroids
Eicosanoids
Fat soluble vitamins
Saponifiable lipids
Formation of soaps, must have linkage present
For soponifcation of lipids to take place you need?
Sodium hydroxide
What is the most abundant of all lipids
Triacylglycerol
What makes up 98% of total dietary lipids?
Triacylglycerol
The remaining 2% of dietary lipids are?
Phospholipids
Cholesterol
Triacylglycerol Is the major component of what?
Fat storage in plant and animal cells mainly in adipocytes
Why are Triacylglycerol much better adapted than glycogen to serve as a storage form of energy?
They are longer to digest and have a greater satiety value
Are Triacylglycerol Polar or non polar?
Non polar
Are Triacylglycerol Soluble to insoluble in water?
Insoluble
Are Triacylglycerol less dense or more dense than water?
Less dense they float
How are Triacylglycerol formed?
Via esterification. Reaction between an alcohol glycerol and a tricarboxylic acid.
Note
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