Types of lipids
1. Fatty acids
describe structure of a fatty acid
*carboxylic acids that contain between 12 and 20 carbon atoms
*tail of a lipid
*nonpolar hydrocarbon chain
Describe head and tail of a fatty acid
head is the carboxl group
tail is the long chain of carbon atoms
Do fatty acids have an even or odd number of carbon atoms?
even number of carbon atoms
What makes a compound a lipid?
lispids is water-insoluble biochemical compound
is a triester formed by combining one glycerol molecule with three fatty acids
When is a triglyceride saturated?
if they contain more saturated than unsaturated fatty acid resifues, and unsaturated if unsaturated fatty acid residues predominate
known as fats are solid are room temperature
vegetable oils are liquids at room temperature
What purpose do triglycerides serve in living things?
*serve as energy storage molecules
*thermal insulation, padding and bouyancy
Name the two classes of phospholipids
Name three types of eicosanoids
What does the steroid cholesterol function?
makes other steriods, including sex hormones, adrenocortoid hormones, and bile salts
What is the function of waxes?
primarily serve a protective function by keeping water either in or out of an organism
What do waxes contain?
esters formed by combining long chain fatty acids with long chain alcohols
Why do the hydrocarbon tails of saturated fatty acids are able to pack closely?
They interact through London Forces
*London forces depend on the surface area of molecules involved, the longer the hydrocarbon tail in a fatty acid the stronger the interaction between molecules
polyunsaturated fatty acids
two or more double bonds
monounsaturated fatty acids
one carbon-carbon double bond
Saturated fatty acids
single bonds joining the carbon atoms in their hydrocarbon tails
How do fatty acids differ from one another?
1. In the number of carbon atoms that they contain
2. In the number of carbon-carbon double bonds
How is the melting point and boiling point affected as the length of the saturated fatty acids increase?
both melting point and boiling points increase
what does the "cis" prefix mean in unsaturated fatty acid
There is a kink in the hydrocarbon tail
*holds the hydrocarbon tails of unsaturated fatty acids farther apart from one another than is the case for saturated fatty acids.
*reduces contact btween molecules and weakens London forces between them
fatty acids with the same number of carbon atoms
the more saturated they are the lower their melting points and boiling points
Why are fatty acids water insoluble?
their carboxyl head groups are not polar enought to counteract the effect of their long, nonplolar hydrocarbon tails
in the body how do fatty acids exist?
exists as anions
What happen to fatty acids when they interact with NaOH?
Ionic compunds are formed of Na+ and fatty acid anions (carboxylate ions) in which the singley bonded oxygen atom as a 1- charge
Waxes are mixtures of
*water insoluble compounds, including esters, alcohols and alkanes
the major component of waxes are produces by combining fatty acids with long chain alcohols
Wax ester consists of
a fatty acid residue attached to a long chain alcohol residue by an ester bond
is that part of a reactant molecule that remains when it has been incorporated into a product
animal fats and vegetable oils are what type of lipids?
triglycerides in which
*three fatty acid residues are joined to a glycerol residue by ester bonds
How many different fatty acid residues do triglycerides contain?
two or three
How are triglycerides formed?
joining three fatty acids to a glycerol molecule by ester bonds
fat stored inadipocytes (fat cells) for future use
vegetable oil is treated with H2 and pt, but reaction is halted before all the double bonds have been removed
*converts liquid vegetable into semisolid poduct
common partially hydrogenated food products
partially hydrogenated oil compared to vegetable oil, which has fewer carbon-carbon double bonds
hydrogenated oil has fewer carbon-carbon double bonds thatn vegetable oil
reaction with H2 and Pt converts an unsaturated triglyceride into a saturated one
catalytic hydrogenation in partial
only some of the carbon-carbon bonds are removed
Which lipid can be reduced, oxidized and saponified?
are formed by combing sphingosine, a fatty acid, and a sugar
What do glycolipids contain?
lipids that contain a sugar residue
*often residue is attached to a sphingosine backbone
*other class of phospholipids
*all contain the alcohol sphingosine
get their name from the fact that phosphate ion PO4 is one of the components used in their formation