-
are family of biomolecules with seemingly unrelated structures
Lipids
-
The word “lipid” comes from the Greek word __
lipos, meaning “fat” or “lard
-
Biological Functions of Lipids
- Energy Source
- Energy Storage
- Cell membrane structural components
- Hormones
- Vitamins
- Vitamin absorption
- Protection
- Insulation
-
When
oxidized, each gram of fat releases _ Kcal of energy
9 kcal
-
serves as a carrier of the lipid-soluble vitamins
Dietary FIber
-
are critical chemical messengers that allow tissues of the body
to communicate with one another
Steroid Hormones
-
make up the
basic structure of all cell membranes
Phosphoglycerides, sphingolipids, and steroids
-
serve as a shock absorber, or protective layer, for the vital organs.
Fats
-
yield fatty acids and glycerol
fats and oils
-
yields fatty acid and long chain alcohol
waxes
-
yield fatty acids, glycerol or sphingosine, phosphoric acid and an
amino alcohol or amino acid
Phospholipids
-
yield fatty acids, sphingosine and a carbohydrate upon hydrolysis
glycolipids
-
Are physiologically potent regulatory molecules called what?
Eicosanoids
-
Examples of eicosanoids
prostaglandins, thromboxanes and leukotrienes,
-
What are fats?
- - solid at room temperature
- – obtained from animal sources, hence, ‘animal fats’
- – contain greater proportion of saturated fatty acids (those with single bonds only)
-
What are oils?
- - liquid at room temperature
- – of plant origin, hence, ‘vegetable oils’
- – contain greater percentage of unsaturated fatty acids (those with one or more
- double bonds
-
are esters composed of three fatty acids joined to
the trihydroxy alcohol, glycerol.
Triglycerides
-
All of the triglycerides obtained from naturally occurring fats and oils contain two or three
different fatty acid components and are thus termed ___
mixed triglyceride
-
General Formula for saturated fatty acid
CH3(CH2)nCOOH
-
contains at least one carbon-to-carbon double bond; the double
bonds found in almost all naturally occurring unsaturated fatty
acids are in the cis-configuration
unsaturated fatty acid
-
Most unsaturated lipid
Oleic
-
Why does unsaturated acid have lower melting point?
because the double bond of unsaturated fatty acid will bend making the Intermolecular forces of attraction weaker thus shorter temperature
-
Why does the melting point of saturated acid greater than the melting point of unsaturated fatty acid?
the reason is that saturated fatty acids have straight –chain structures that allow their molecules to fit close together and form strong attractions.
-
Why do we need to include at least two servings of “oily” fish in our diet each week?
- The reason for this recommendation is that
- these fish contain high levels of two omega-3 fatty acids called eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) which can reduce the risk of cardivascular diseases by decreasing blood clot formation blood triglyceride levels, and growth of atherosclerotic plaque
-
- precursor for the synthesis of prostacyclin, which inhibits clumping of platelets and
thus reduces clot formation.
eicosapentaenoic acid (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
docosahexaenoic acid (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.
- ALPHA-linolenic acid
- (ALA)
-
is also an essential fatty acid, required for the synthesis of arachidonic acid
Linoleic Acid
-
omega-3 fatty acids are precursors of prostaglandins that have
anti-inflammatory effects
-
omega-6 fatty acids are precursors of prostaglandins that have
inflammatory effects
-
addition of H2 to double bonds of unsaturated fatty acids in lipids, converting them
to single bonds of saturated fatty acids.
Hydrogenation
-
__ of a liquid vegetable oil changes it to a soft, semisolid fat
partial hydrogenation
-
Why is coconut oil more healthy to use?
Because coconut oil is a saturated acid, thus it has no double bonds. As we all know double bonds are prone to oxidation, and when this is oxidized, it could lead to rancidity.
-
addition of water to ester bonds of lipids in the presence of strong acids or digestive
enzymes called lipases
Hydrolysis
-
reaction of lipids with a strong base (alkaline hydrolysis) to give glycerol and salts of
the fatty acids (called soaps)
Saponification
-
When ___ is used, a solid soap is produced that can be molded into a desired shape;
NaOH
-
produces a softer, liquid soap
KOH
-
Explain the cleaning action of soap
The nonpolar portion of the soap molecule dissolves in the grease and oil accompanying dirt on clothing and dishes. The polar ends of the soap molecules are attached to water and pull the grease or oil into the aqueous solution.
-
soap molecules coat the oil or grease, forming clusters called
miscelles
-
Explain why fats or oils become rancid
It becomes rancid when its double bonds are oxidized by oxygen and microorganisms
-
The term __ is applied to any fat or oil that develops a disagreeable odor.
rancid
-
Two principal
chemical reactions are responsible for causing rancidity
Hydrolysis and Oxidation
-
___ is an ester of a saturated fatty acid and a long-chain alcohol, each containing from 14 to
30 carbon atoms.
Wax
-
found in the surfaces of leaves and stems and serve to protect the plant from
dehydration and from invasion by harmful organisms
Plant Wax
-
also serve as protective coatings; found on the surface of feathers, skin, and hair
and help keep these surfaces soft and pliable
Animal Wax
-
wax obtained from honeycombs
Beeswax
-
wax obtained from palm trees are used to give a protective coating to furniture, cars, and floors
carnauba wax
-
a wax that is used in making candles and cosmetics such as lipstick
Jojoba wax
-
a mixture of waxes obtained from wool, is used in hand and facial lotions to aid retention of water, softening the skin.
Lanolin
-
These are esters of glycerol like the triacylglycerols or triglycerides but with a phosphate ester in
place of one fatty acid ester group
Glycerophospholipids or phosphoglycerides
-
contains the important quaternary ammonium salt, choline, HOCH2CH2N(CH3)3, joined
to the phosphoric acid residue
Lechitin
-
ethanolamine, HOCH2CH2NH2 or serine, HOCH2CH(NH2)COOH is linked to the
phosphate moiety
Cephalines
-
are major components of cells membranes in
all higher organisms and are also important as source of the choline needed in transmission of nerve
signals
phosphatidylcholines or lecithin
-
2 Emulsifying agents
Phosphatidylcholine and other glycerophospholipids, Phosphatidylethanolamine and phosphatidylserine
-
These are a group of phospholipids that are abundant in brain and nerve tissues. They are derivatives of the amino alcohol sphingosine instead of glycerol
Spingolipids
-
___ of the lipids of the myelin
sheath are sphingomyelins
25%
-
contain both carbohydrate and
lipid parts but no phosphorus.
Glycolipids
-
characterized by the presence of a single monosaccharide head group
Cerebrosides
-
cerebrosides that are found in the membranes of macrophages (cells that protect the body by ingesting and destroying foreign microorganisms)
Glucocerebroside
-
cerebrosides found almost exclusively in the membranes of brain cells
galactocerebroside
-
possess oligosaccharide groups, including one or more molecules of N -
acetylneuraminic acid (sialic acid)
Gangliosides
-
The most abundant lipid which control the in and out of ions
Phospoglycerides
-
Explain how can polar bears without eating for 8 months or more
Polar bears hibernate 8 months or more meaning they do not move and they do not eat for 8 months. The food of polar bears are seal blobber which contains tons of fats. Because of these, Polar bears have massive TAG reserves. Meaning the energy that they get without eating comes from their tag reserves. Water is also provided because of the metabolism of TAG
-
Two main types of lipids occur in biological membranes
phospholipids and sterols
-
The predominant phospholipids in most membranes
phosphoacylglycerols or phosphoglycerides.
-
membranes from animal cells usually contain a second group
of polar lipid called
sphingolipids
-
The second major type of lipid found in some biological membranes is
Cholesterol
-
suggests that a cell membrane consists of phospholipid molecules that form into a bilipid layer
Fluid Mosaic model
-
2 Kinds of Protein in Cell Membrane
- Peripheral membrane protein- on the surface
- Integral membrane protein- are embedded within the membrane
-
Why is the lipid bilayer fluid?
Because of High % of Unsaturated Fatty Acid
-
Regulates membrane fluidity
Cholesterol
-
are lipids that are bonded to other types of molecules
Complex Lipids
-
The most common and
important complex lipids are __ which are responsible for the transport of other lipids
in the body
plasma lipoproteins
-
– density, less than 0.95 g/mL
– carry dietary triglycerides from the intestine to other tissues
Chylomicrons
-
– density, 0.95–1.019 g/mL.
– bind triglycerides synthesized in the liver and carry them to adipose and
other tissues for storage
Very Low Density Lipoproteins
-
– density, 1.019–1.063 g/mL.
– carries cholesterol to peripheral tissues and help regulate cholesterol levels
in those tissues; richest in cholesterol, frequently carrying 40% of the
plasma cholesterol; allows accumulation.
Low density lipoproteins (LDL)
-
bound to plasma cholesterol; however, they transport cholesterol from
peripheral tissues to the liver for removal.
High Density Lipoprotein (HDL)
-
are compounds containing the steroid nucleus, which consists of three cyclohexane rings and one cyclopentane ring fused together
Steroids
-
The most abundant animal steroid
Cholesterol
-
are chemical messengers that mediate biochemical events in target tissues
Hormones
-
Two major classes of steroid hormones
Sex Hormones and adrenocortical hormones
-
Responsible both for the development of male secondary sex characteristic during puberty
and for promoting tissue and muscle growth.
Male Sex Hormones or androgens
-
hardening of the arteries
atherosclerosis
-
Sex hormones essential for preparing the uterus for implantation of a fertilized ovum during
pregnancy
progestin
-
hormone that regulate a variety of metabolic processes
adrenocortical hormones
-
Aldosterone controls tissue swelling by regulating the delicate cellular salt balance between Na and K
mineralocorticoids e.g. aldosterone
-
Involved in the regulation of glucose metabolism and in the control of inflammation (e.g. used in the treatment of rheumatoid arthritis; also asthma, GI disorder, many skin
conditions and a variety of other diseases)
glucocorticoids
-
appear to function by tricking the body into thinking its pregnant and therefore temporarily infertile.
Oral Contraceptives
-
detected in several athletes during the 1988 Olympics, are synthetic androgens that mimic the tissue building effect of testosterone
Anabolic Steroids
-
produced by the liver (from cholesterol), stored in the gall bladder and secreted into the
intestine
Bile salts
-
are lipids found in the oils of some plants and flowers that give them their
characteristic odors and colors
Terpenes
-
The fat – soluble vitamins are
Vitamins A, E and K
-
vitamin that is required for the formation of the visual pigment found in the retina of the eye
Vitamin A
-
vitamin that prevents oxidation of unsaturated fatty acids in cellular membranes (antioxidant).
Vitamin E
-
vitamin that is needed in the formation of prothrombin for blood clotting
Vitamin K
-
Simple lipids
- a. fats and oils
- b. waxes
-
Compound lipids
phospholipids, glycolipids
-
two important families of lipids that do not contain fatty acids; they are included in the lipid family because they are not soluble in water
Terpenes and Steroids
-
are aggregates of triglycerides and protein that transport dietary triglycerides to cells throughout the body.
Chylomicrons
-
unsaturated carboxylic acids consisting of a 20–carbon skeleton that contains a cyclopentane ring; extremely potent biological molecules with hormone-like activity.
Prostaglandins
-
contain three conjugated double bonds and differ from prostaglandins by the absence of the ring.
Leukotrienes
-
promotes platelet aggregation and
smooth muscle contraction.
Thromboxanes
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