Lipids I Flashcards
are family of biomolecules with seemingly unrelated structures. They are sparingly soluble in water and have diverse biological functions.
Lipids
fatty acids commonly found in animals as________,which are stored mainly in adipose cells (adipocytes)
triacylglycerols
CLASSIFICATION OF LIPIDS
triacylglycerols
Energy-storage lipids
CLASSIFICATION OF LIPIDS
phospholipids, sphingoglycolipids,
and cholesterol
Membrane lipids
CLASSIFICATION OF LIPIDS
bile acids
Emulsification lipids
CLASSIFICATION OF LIPIDS
steroid hormones and eicosanoids
Chemical messenger lipids
CLASSIFICATION OF LIPIDS
biological waxes
Protective-coating lipids
CLASSIFICATION OF LIPIDS
lipoproteins
Transport lipids
Simple lipids
a. – yield fatty acids and glycerol
b. – yield fatty acids and long chain alcohol
fats and oils
waxes
Compound lipids
a. – yield fatty acids, glycerol or sphingosine,
phosphoric acid and an amino alcohol or amino acid
b. – yield fatty acids, sphingosine and a carbohydrate upon hydrolysis.
phospholipids
glycolipids
is a fatty acid with a carbon chain in which two or more carbon–carbon double bonds are present.
polyunsaturated fatty acid
- an unsaturated fatty acid with its
endmost double bond three carbon atoms away from its
methyl end.
Omega (ω)-3 fatty acids
- an unsaturated fatty acid with its
endmost double bond six carbon atoms away from its methyl end.
Omega (ω)-6 fatty
precursor for the synthesis of prostacyclin, which inhibits clumping of 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
_______ is also an essential fatty acid, required for the synthesis of _______, the precursor for many prostaglandins.
Linoleic acid
arachidonic acid
are precursors of prostaglandins that exhibit anti-inflammatory effects
Omega-3 fatty acids
are precursors to prostaglandins that have inflammatory effects.
omega-6 fatty acids
- are esters composed of three fatty acids joined to the trihydroxy alcohol, glycerol.
Triglycerides or triacylglycerols (TAG)
– solid at room temperature
– obtained from animal sources, hence, ‘animal fats’
– contain greater proportion of saturated fatty acids (those with single Bonds only)
FATS
- liquid at room temperature
- of plant origin, hence, ‘vegetable oils’
- contain greater percentage of unsaturated fatty acids (those with one or more double bonds)
OILS
The yellow color of butter is due to the presence of the
pigment ______
carotene
Storage site of triacylglycerols in animals
Adipose tissues (adipocytes/fat cells)
Addition of H2 to double bonds of unsaturated fatty acids in lipids, converting them to single bonds of saturated fatty acids.
Hydrogenation
Addition of water to ester bonds of lipids in the presence of strong acids or digestive enzymes called _______.
Hydrolysis
Lipases
Reaction of lipids with a strong base (alkaline hydrolysis) to give glycerol and salts of the fatty acids (called soaps).
Saponification
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
Butter is particularly susceptible to rancidity because it contains many of the lower molar mass acids (butyric, caproic) all of which have offensive odors. Under moist and warm conditions, hydrolysis of the ester linkages occurs, liberating the volatile acids.
Hydrolytic rancidity
Occurs in triglycerides containing unsaturated fatty acids.
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.
Antioxidants
is a monoester of a long-chain fatty acid and a long-chain alcohol.
biological wax
found in the surfaces of leaves and stems and serve to protect the plant from dehydration and from invasion by harmful organisms.
Plant waxes
also serve as protective coatings; found on the surface of feathers, skin, and hair and help keep these surfaces soft and pliable.
Animal waxes
