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CH 17 Lipids

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triacylglycerol
glycerol with 3 fatty acids attached
Lipids are
biomolecules that contain fatty acids or a steroid nucleus
Lipids are
soluble in organic and non-polar solvents but not in water
Lipids are
extracted from cells using organic solvents
The lipids that contain fatty acids are:
waxes
fats and oils (triacylglycerols or triglycerides)
glycerophospholipids
prostaglandins
fats and oils AKA
(triacylglycerols or triglycerides)
The types of lipids that do not contain fatty acids are
steroids
Fatty acids are:
are long-chain carboxylic acids
Fatty acids are:
typically contain 12 to 18 carbon atoms
Fatty acids are:
are insoluble in water
Fatty acids are:
can be saturated or unsaturated
The formulas for fatty acids are written as
condensed structural formulas
line-bond formulas
Saturated fatty acids have
single C—C bonds
Saturated fatty acids have
molecules that fit closely together in a regular pattern
Saturated fatty acids have
high melting points that make them solids at room temperature
Saturated fatty acids have
strong attractions between fatty acid chains
Type Saturated Fatty Acids
lauric acid
Type Saturated Fatty Acids
myristic acid
Type Saturated Fatty Acids
palmitic acid
Type Saturated Fatty Acid
stearic acid
Unsaturated fatty acids have
one or more C=C bond
Unsaturated fatty acids typically contain
cis =
Unsaturated fatty acids have
bends/kinks, therefore don't stack well
Trans = bonds are not common and mostly occur when:
there is hydrogenation of cis
Type of Monounsaturated Fatty Acid
palmitoleic acid
Type of Monounsaturated Fatty Acid
oleic acid
Type of Polyunsaturated Fatty Acid
linoleic acid
Type of Polyunsaturated Fatty Acid
linolenic acid
Type of Polyunsaturated Fatty Acid
arachidonic acid
Unsaturated fatty acids have
fewer attractions between chains
Unsaturated fatty acids have
lower melting points (the more double bonds, the lower the m.p.)
Unsaturated fatty acids are
liquids at room temperature
Omega-6 are
in vegetable oils are mostly omega-6
with the first C═C at C6 from the ω CH3- end
Omega-3 are
in fish oils are mostly omega-3 with the first C═C at C3 from the ω CH3- end
Prostaglandins are
derived from arachidonic acid
Prostaglandins have
a five-carbon ring
Prostaglandins have
20 carbon atoms in their fatty acid chains
Prostaglandins have
an -OH on carbons 11 and 15
Prostaglandins have
a trans double bond at carbon 13
Prostaglandins are
not produced when anti-inflammatory drugs such as aspirin (& other NSAIDs) inhibit their synthesis
Prostaglandins are
involved in pain, fever, and inflammation
Prostaglandins are
produced by injured tissues
Fatty acids have what at the end?
COOH (carboxylic acid)
Waxes are
esters of saturated fatty acids and long-chain alcohols
Waxes are
coatings that prevent loss of water from leaves of plants
Fats and oils are
formed when the hydroxyl groups of glycerol react with the carboxyl groups of fatty acids
Fats and oils are
esters of glycerol
Fats and oils are
produced by esterification
Fats and oils are
also called triacylglycerols (TAGs) or triglycerides
glycerol
CH₂-O-H

CH-O-H

CH₂-O-H
In a triacylglycerol what forms ester bonds with 3 fatty acids?
glycerol
Olive oil contains a high percentage of
oleic acid
oleic acid is a
monounsaturated fatty acid with one cis double bond
A triacylglycerol that is usually called a fat
Dietary fat acts as a carrier of lipid-soluble vitamins into cells of small intestine
A triacylglycerol that is usually called a fat
Provide shock absorption and insulation
A triacylglycerol that is usually called a fat
provide energy storage in adipocytes
A triacylglycerol that is usually called a fat
is prevalent in meats, whole milk, butter, and cheese
A triacylglycerol that is usually called a fat
is solid at room temperature
A triacylglycerol that is usually called an oil
is liquid at room temperature
A triacylglycerol that is usually called an oil
is prevalent in plants such as olive and safflower
Oils with Unsaturated Fatty Acids
are liquids at room temperature
Oils with Unsaturated Fatty Acids
have lower melting points than do saturated fats
Oils with Unsaturated Fatty Acids
cannot pack triacylglycerol molecules as close together as in fats
Oils with Unsaturated Fatty Acids
have cis double bonds that cause "kinks" in the fatty acid chains
Oils with Unsaturated Fatty Acids
have more unsaturated fats
Oils with Unsaturated Fatty Acids
have kinks that do not allow close packing.
The chemical reactions of triacylglycerols are similar to those of
alkenes and esters.
In hydrogenation, double bonds in unsaturated fatty acids react with:
H2 in the presence of a Ni or Pt catalyst.
The hydrogenation of oils converts
double bonds to single bonds
The hydrogenation of oils adds
hydrogen (H2) to the carbon atoms of double bonds
The hydrogenation of oils increases
the melting point
The hydrogenation of oils produces
solids such as:
margarine and shortening
Unsaturated fatty acids can be: Cis with bulky groups on the ______ side of C═C
SAME
Unsaturated fatty acids can be: trans with bulky groups on the ______ side of C═C
OPPOSITE
Trans fatty acids are formed during:
hydrogenation when cis double bonds are converted to trans double bonds
Trans fatty acids in the body behave like:
saturated fatty acids
Trans fatty acids are estimated to make up: __ to __ % of our total calories
2 to 4
Trans fatty acids in several studies are reported to raise _____ -cholesterol and lower ___ -cholesterol.
LDL
HDL
In vegetable oils, the unsaturated fats usually
contain cis double bonds
In vegetable oils, during hydrogenation some ___ double bonds are converted to ____ double bonds (more stable), causing a change in the fatty acid ______
cis
trans
structure
In vegetable oils, a label states "partially" or "fully hydrogenated" if the fats contain:
trans fatty acids
Olestra is used in foods as
an artificial fat
Olestra is ____ linked by ____ bonds to several long-chain fatty chains
sucrose
ester
Olestra is not broken down in the _____ _____ (provides no nutrition, but excreted)
intestinal tract
are there more unsaturated fats in vegetable oils?
yes
Does hydrogenation of oils converts some cis-double bonds to trans-double bonds?
yes
Do animal fats have more saturated fats?
yes
Plants are usually oils that are ___ with ___ bonds and are ___ at room temp
unsaturated
kinky
liquid
Animal fat is usually _____ with ____ chains and are ____ at room temp
saturated
straight chains
solid
Double bonds of unsaturated fats can auto-oxidize in ___, and via _______
air
microorganisms
Oxidation of Unsaturated Fats Products are:
short-chain ________, which can be further oxidized to ______ _____
aldehydes
carboxylic acids
-CH=CH- → -CHO + OHC- → -COOH + HOOC-
Oxidation of Unsaturated Fats products
stink - rancidity
Oxidation of Unsaturated Fats Reactions are accelerated by trace ___ ____ ; inhibited by antioxidants, & /or chelating agents which trap metal ions
metal ions
Oxidation of Unsaturated Fats Happens in ___ exposed to air, on ____ skin
oils
sweaty
In acid or enzyme hydrolysis, of Triacylglycerols:
water adds to the _____ bonds
ester
In acid or enzyme hydrolysis, of Triacylglycerols: triacylglycerols split into _____ and three ____ ____
glycerol
fatty acids
In acid or enzyme hydrolysis, of Triacylglycerols:
an acid or enzyme _____ is required
catalyst