BIOCHEM- LEC REVIEWER
Saturated fatty acids contain no double bonds carbon
Unsaturated fatty acids contain one or more double bonds
*atherosclerosis- formation or clogging of fats in the walls of
the arteries forming plaques that constricts blood flow
*hydrolysis- breaking of molecules through the addition of
water; fats and oils can be hydrolyzed in the presence of acid,
a base or a specific enzyme lipases-- saponification.
FAT / OIL + STRONG BASE → GLYCEROL + SALTS (SOAP) OF
FATTY ACIDS
Micelles: a carboxylate. ex.: soap- the hydrophobic (attracts
the dirt) and hydrophilic part loves the water. Soluble in
water
Sodium stearate- soap
sodium lauryl sulfate- detergent
Hydrogenation- the addition of H2 in C=C (or fatty acids). It
converts unsaturated fats to saturated fats. Adding hydrogen
to unsaturated molecules make it stable.
Ex.: partial hydrogenation>> semi solid fat
complete hydrogenation>> brittle fats
Oxidation- ganing oxygen; losing hydrogen>> rancidity, bad
odor or taste.
Butter releases foul-smelling butyric acid, caprylic and capric
acids. Microorganisms present in the air furnish lipases that
catalyze this process. Hydrolytic rancidity can easily be
prevented by covering the fat or oil and keeping it in a
refrigerator.
Body odor. 3-methyl-2-hexenoic acid is largely responsible
for body odor.
Premature aging is also related to oxidation of the
phospholipid bilayer in the cell membrane caused by excess
free radicals (natural or artificial: diet, lifestyle and
environment factors) that could be neutralized by
antioxidants such as A, C, E and glutathione.
Classification of Lipids
Saponifiable lipids simple= waxes & triglycerides
complex= phosphoglycerides & sphingolipids
Nonsaponifiable lipids steroids & prostaglandins
Based on their reaction with water
Hydrolysable lipids- are compounds that can be converted
into smaller molecules by hydrolysis; derived from fatty acids.
: waxes; triacylglycerols; phospholipids
Non-hydrolysable lipids- these are compounds that cannot
be cleaved into smaller molecules by hydrolysis
: steroids; fat-soluble vitamins; eicosanoids
Simple lipids- lipids which yield fatty acids and alcohol upon
hydrolysis; esters of fatty acids
simple lipid+ H2O fatty acid(s) + alcohol
Complex lipids- lipids that yields fatty acids, alcohol and other
compounds upon hydrolysis; found in cell membranes, brain,
nervous tissues, myelin sheaths of nerves and blood platelets.
Precursor and derived lipids- are compounds produced when
simple complex lipids undergo hydrolysis. They include
substances such as fatty acids, glycerol, sphingosine and other
alcohols. Derived lipids are formed by the metabolic
transformation of fatty acids. They include steroids, fat-
soluble vitamins, hormones, ketone bodies and eicosanoids.
Fatty acids:
▬saturated fatty acids- contain single bonds
inert; unreactive
straight-chain structures
allow their molecules to fit close together and form
attractions
have no double bonds
fatty/ waxy solids at room temperature
high boiling & melting points
ends in ANOIC ACID
12:0 – lauric acid
14:0 – myristic acid
16:0 – palmitic acid
18:0 – stearic acid
20:0 – arachidic acid
▬unsaturated fatty acids:
monounsaturated fatty acids- with one double bond
16:1 – palmitoleic acid (and oleic acid) are the major human
monounsaturated fatty acids.
18:1 – oleic acid- possible the most common fatty acid in
natural fats.
Many plants and vegetable oils re mono-unsaturated fatty
acids therefore are good for you. Most naturally occurring
unsaturated fatty acids occur in –cis- configuration
polyunsaturated fatty acids- those with two or more
carbon-carbon double bonds.
18:2 – linoleic acid
18:3 – linolenic acid
20:3 – arachidonic acid
20:5 – EPA (eicosapentaenoic acid)
22:6 – DHA (docosahexaenoic acid)
Unsaturated fatty acids:
Cis fatty acids- have two hydrogen atoms on the same side
of the double bond
Trans fatty acids- have two hydrogen on the opposite side
of the double bond, which results in a similar structure to
that of saturated fatty acid (not healthy fats).
▬Eicosanoid- a class of molecules derived from 20-carbon
polyunsaturated fatty acids, most frequesntly arachidonic
acid; include the
Prostaglandins- dilates blood vessels and inhibits the
formation of blood clots
Thromboxanes- a prostaglandin that constricts blood
vessels and causes blood clotting.
Leukotrienes- a prostaglandin that produces muscle
contrractions, especially in the lungs and thereby
causing asthma-like attacks/ inflammations.
and prostacyclins (under prostaglandin); cell membranes
release arachidonic acid in response to a variety of
circumstances/ physiological triggers, including infection
and allergic reactions.
Eicosanoids are NSAIDs (non-steroidal anti-inflammatory
drugs). Blocks the oxidation of arachidonic acid from
prostaglandins and thromboxanes. Ex.: aspirin, ibuprofen,
ketoprofen, celecoxib.
