The primary role of lipids is forming
cell membranes, the bilipid layer common to all living things bacteria
and human. Through evolution lipids have been put to use as storage
of energy in the form of fats and oils. An extremely important role
of lipids is the further evolution into more complex structures such as
cholesterol and other biologically active molecules.
After this lecture you will:
understand the structure of lipids
see how lipids are created from glycerol and
learn what essential fatty acids are
learn how cell membranes are made from lipids-triglycerides
understand the role of cholesterol and how
it is made
find out what other biologically active molecules
are made from lipids
LIPIDS (fats and oils): TRIGLYCERIDE
|Fats and oils are both
lipids. However, by convention liquid lipids are called oils and
solid lipids are called fats.
TO WATCH THE FORMATION OF TRIGLYCERIDES
|From carbohydrates comes sugars and glycerin
LIPIDS start with a "frame" of a triple
(that OH is the alcohol part) calledglycerol
|THEN, long chains of
fatty acids are added to each OH by dehydration
(an acid means a COOH is on one end)
|Put the glycerin and fatty acids together
by dehydration synthesis (remove a water) and get...........
Saturated and unsaturated fatty acids,
cis and trans fatty acids click HERE
What is wrong with trans fatty acids ?
|ESSENTIAL FATTY ACIDS
They are called
"essential" because we must eat them. We cannot make all the different
lengths of fatty acids we need. Two of these are:
1. linoleic acid (omega-6)
2. alpha-linolenic acid (omega-3)
They are essential because they are precursors
for molecules that regulate numerous body functions
including blood pressure, blood viscosity, vasoconstriction, immune and
MORE READING HERE.
IT IS NECESSARY TO BE CAREFUL SINCE THERE IS A LOT OF SELLING GOING ON
ABOUT THIS TOPIC.
has two, rather then three, fatty acid chains attached to a glycerol molecule.
- a phosphate (PO4) is in place of the
third chain attached to a CH2-CH2-N- (CH2)3
- is negatively charged and interacts
nicely with water (hydrophilic)
-- the fatty chains are hydrophobic and
don't interact with water.
|- when simply dumped into water phospholipids
form single layers, double layers AKA bilipid layer or spheres (called
micelles) with the heads oriented toward the water and the tails oriented
away from it.
- double phospholipid layers forms a barrier
with an outside and an inside.. this is essential for a cell because it
keeps stuff inside and other stuff outside in a liquid environment
|-- cell membranes must be flexible. This
is possible because the phospholipids are not chemically bonded together,
rather they stay together because of the hydrophilic and hydrophobic interactions.
- The greater the concentration of unsaturated
fatty acid tails in the phospholipids the more fluid is the membrane.
- The double bond in the fatty acid prevents
the fatty acid tails from packing tightly together.
CHOLESTEROL AND OTHER BIOLOGICALLY
ACTIVE MOLECULES MADE FROM LIPIDS
- has a ring structure (pic)
-- is a major component of cell membranes
- helps to 'pack' phospholipids giving
more rigidity to the membranes
-- it is converted to vitamin D (if irradiated
-- can be modified to form steroid hormones
-- is modified to bile acids to digest
- your body makes cholesterol whether
or not you eat it
-- Steroids are REGULATORY molecules
-- sex hormones estrogen and testosterone
and vitamins A, D, and E.
|VITAMINS AND MINERALS
-- some enzymes require small organic
molecules called cofactors in order to function properly. Vitamins are
the source of these cofactors.
-- Vitamins A, D, E, and K are soluble
in fat and are stored in fat, the rest are water soluble
- vitamins like folic acid are required
for DNA repair
-- The body requires inorganic elements
-- Calcium and potassium are found in
bones and teeth.
-- Sodium and potassium are essential
in the operation of nerve cells.
-- Sulfur is found in proteins, magnesium
is a constituent of enzymes, zinc is a coenzyme, and iodine is a component
of the thyroid hormone.
-- Iron and copper are necessary for hemoglobin.
- too much of some of these minerals can
Pantothenic Acid carrier
of activated acyl, acetyl groups
What is the difference between fats, oils
What kind of structure does lipids form?
What kind of regulatory molecules are
made from lipids?
What is the difference between a solid
oil and a liquid oil?
What two kinds of molecules make up tri-glycerides?
What is glycerol used for in the body?
What three kinds of molecules make up
phospholipids? What is it used for?
What is dehydration synthesis?
What are 3 functions of cholesterol?
What are steroids?
Why are vitamins and minerals needed?