lip= fat
- Makes up 18 - 25 % of body mass in lean adults.
-Contain CARBON, HYDROGEN and OXYGEN.
But they do not have a 2:1 ratio of hydrogen to oxygen
LIPIDS ARE HYDROPHILIC
The proportion of electronegative oxygen atoms in lipids is usually smaller than carbohydrates.
- so there are fewer polar covalent bonds.
As a result , most lipids are insoluble in polar solvents such as water.
Only the smallest lipids (some fatty acids ) can dissolve in watery blood plasma.
LIPOPROTEINS
To become more soluble in blood plasma, lipidn molecules join with hydrophilic protein molecules.
The resulting lipid- protein complexes are called lipoproteins.
-Are soluble
- because proteins are outside and
lipids are on the inside.
LIPID FAMILY
1. FATTY ACIDS
2. TRIGLYCERIDES
3. PHOSPHOLIPIDS
4. STEROIDS
5. EICOSANOIDS
6. OTHERS
1. FATTY ACIDS
- Used to synthesize triglycerides and phospholipids.
- catabolized to generate ATP.
- consists of
- a carboxyl group
and
- a hydrocarbon group chain.
- can be either saturated or unsaturated.
1. SATURATED FATTY ACID
- Contains only single covalent bond between carbon atoms of the hydrocarbon chain.
Because they lack double bonds, each carbon atom of hydrocarbon chain is saturated with hydrogen atom.
eg. Palmitic acid C15H31COOH.
2. UNSATURATED FATTY ACID
Contains
1 orv more double covalent bonds between carbon atoms of the hydrocarbon chain.
Thus the fatty acid is not completely saturated with hydrogen atoms.
eg. Oleic acid C17H33COOH
The unsaturated fatty acid has a KINK/ BEND at the site of the double bond.
MONOUNSATURATED FATTY ACID
If fatty acid has just 1 double bond in hydrocarbon chain.
eg. Oleic acid.
POLYUNSATURATED FATTY ACID - PUFA
If fatty acid more than 1 double bond in hydrocarbon chain.
- contains more than a kink / bend
eg. Omega-3 fatty acids
FATTY ACIDS IN HEALTH AND DISEASE
ESSENTIAL FATTY ACIDS
- A group of fatty acids essential to human health
- Cannot be made by human body.
- Must be obtained from foods or supplements.
MOST IMPORTANT ESSENTIAL FATTY ACIDS
1. OMEGA-3 FATTY ACIDS
2. OMEGA-6 FATTY ACIDS
3. cis- FATTY ACIDS
OMEGA-3 and OMEGA-6 FATTY ACIDS
-Poly unsaturated fatty acids
-Believed to work together to promote health.
1. may have a protective effect against heart disease and stroke.
- by lowering total cholesterol
- raising HDL / good cholesterol.
- lowering LDL / bad cholesterol.
2. Decrease bone loss
- by increasing calcium utilization by body.
3. Reduce symptoms of arthritis due to inflammation
4. Improve certain skin disorders
- psoriasis
- eczema
- acne
5. Improve mental functions.
PRIMARY SOURCES OF OMEGA-3 FATTY ACIDS
- Flax seed
- Fatty fish
- Fish oils
- Walnuts
- Oils that have large amounts of poly unsaturated fatty acids.
PRIMARY SOURCES OF OMEGA-6 FATTY ACIDS
- Processed foods
- cereals
- breads
- white rice
- Baked goods
- Eggs
- Oils that have large amounts of poly unsaturated fatty acids.
- Meat especially organ meats such as liver.
CIS- FATTY ACIDS
- An unsaturated fatty acid with with hydrogen atom on either side of the double bond are on the same side of the unsaturated fatty acid
- are nutritionally beneficial.
- used by the body to produce hormone like regulators and cell membrane
When cis- fatty acids are heated , pressurized and combined with a catalyst (usually nickel) by hydrogenation
- they are changed to unhealthy trans- fatty acids
TRANS- FATTY ACIDS
Hydrogen atoms are on opposite sides of the double bond of an unsaturated fatty acid
Hydrogenation is used by manufacturers to make vegetable oils solid at room temperature
-and less likely to turn rancid.
Hydrogenated / trans- fatty acids are common in
- commercially baked goods
- crackers
- cakes
- cookies
- salty snack foods
- some margarines
fried foods- donuts, french fries
When oil is used fro frying, and if the oils reused,
- cis- fatty acids are converted to trans- fatty acids.
If a product label contains the word hydrogenated or partially hydrogenated,
- then the product contains trans - fatty acids
ADVERSE EFFECTS OF TRANS- FATTY ACIDS
1. Increase in total cholesterol.
2. Decrease in HDL.
3. Increase in LDL.
4. Increase in triglycerides.
5. Increase risk of heart diseases and other cardio-vascular diseases.
2. TRIGLYCERIDES / TRIGLYCEROLS
tri=3
The most plentiful lipids in our body and diet.
- consists of 2 types of building blocks.
- a single glycerol molecule
- 3 fatty acid molecules.
- a 3- carbon glycerol molecule forms the backbone of a triglyceride.
- 3 fatty acids are attached by Dehydration synthesis reactions
- one to each carbon of the glycerol backbone.
- The chemical bond formed where each water molecule is removed is an ester linkage
The reverse reaction- HYDROLYSIS-
- breaks down a single molecule of a triglyceride into 3 fatty acids
HYDROLYSIS
TRIGLYCERIDES - 3 FATTY ACIDS
FUNCTIONS
- Bodys most highly concentrated form of chemical energy .
- provide more than twice as much energy per gram as do carbohydrates and proteins.
- Our capacity to store triglycerides in adipose tissue is unlimited for practical purposes.
- Excess carbohydrates, proteins, fats and oils are deposited in adipose tissues as triglycerides.
FAT
Triglycerides that us solid at room temperature.
- Fatty acids of a fat are mostly saturated.
- these lack double bonds in their hydrocarbon chains,
- they can closely pack together and solidify at room temperature.
SATURATED FAT
- A fat that mainly consists of saturated fatty acids.
- Occur
- mostly in meats especially red meats.
- nonskim dairy products
- whole milk
- cheese
- butter
- in cocoa butter
- palm oil
- coconut oil
Diets that conatin large amounts of saturate dfats are associated with disorders sucha s heart disease and colorectal cancer.
OIL
Triglycerides that is liquid at room temperature .
-Fats of oil are mostly unsaturated.
The kinks at the sites of the double bonds prevent unsaturated fatty acids of an oil from closely packing together and solidifying.
The fatty acids of an oil can be either
- monounsaturated
OR
- polyunsaturated
MONOUNSATURATED FATS
- Contain triglycerides with monounsaturated fatty acid.
eg.
olive oil
peanut oil
canola il
most nuts
avocados
POLYUNSATURATED FATS
- Contain triglyceride that mostly consist of polyunsaturated fatty acids.
eg.
corn oil
safflower oil
sunflower oil
soyabean oil
fatty fish - salmon
- tuna
- mackerel
Both monounsaturated and polyunsaturated fats are believed to decrease the risk of heart disease.
3. PHOSPHOLIPIDS
- Lipids that contain phosphorus.
- Major lipid component of cell membrane.
- Have a glycerol backbone
and
2 fatty acid chains attached to the first carbon atom
HEAD POSITION
-In the third position a phosphate group (PO4 3-) links a small charged group that usually contains nitrogen to the backbone.
-Is polar.
- Can form hydrogen bonds with water molecules.
TAIL POSITION
- the 2 fatty acids
- Non polar
- Can interact only with other lipids.
AMPHIPATHIC
amphi= on both sides
-pathic= feeling
- Molecules that have both polar and non polar parts.
- Amphipathic phospholipids line up tail to tail in a double row to make up much of the membrane that surrounds each cell.
4. STEROIDS
- Lipids that have 4 rings of carbon atoms.
- Body cells synthesize other steroids from cholesterol
- which has a large non polar region.
- consists of 4 rings and a hydrocarbon tail.
COMMON STEROIDS IN BODY
These are known as STEROLS
- because they also have at least 1 hydroxyl(alcohol) group -OH.
The polar hydroxyl groups make sterol weakly amphipathic.
a. CHOLESTEROL
-Minor component of all animal cell membranes.
- Precursor of bile salts
Vitamin D
steroid hormone
b. BILE SALTS
- Needed for lipid digestion
and absorption of dietary lipids.
c. Vitamin D
- Helps to regulate calcium level in body.
- Needed for bone growth and repair.
d. Adrenocortical hormones
-Help regulate metabolism
resistance to stress
salt and water balance.
eg.
Cortisol- for maintaining normal blood sugar levels.
e. SEX HORMONES
- Stimulate reproductive functions and sexual characteristics
eg. estrogen
testosterone
5. EICOSANOIDS
eicosan= 20
- Lipids derived from a 20 carbon fatty acid called arachidonic acid.
2 PRINCIPAL CLASSES
A. PROSTAGLANDIN
B. LEUKOTRIENES
A. Prostaglandin
- a. modify responses to hormones.
- b. contributes to inflammatory response.
- c. influence formation of blood clots.
- d. regulate body temperature.
- e. dilate air ways to the lungs.
- f. prevent stomach ulcers.
B. Leukotrienes
- participate in allergic and inflammatory responses.
6. OTHERS
A. FAT SOLUBLE VITAMINS
B. LIPOPROTEINS
a. FAT SOLUBLE VITAMINS
1. CAROTENES
- Yellow - orange pigments in egg yolk
carrots
tomatoes
- needed for synthesis of Vitamin- A
- functions as anti oxidants.
2. VITAMINS A,D,E,K
a. VITAMIN-A
- Used to make visual pigments in the eye.
b. Vitamin D
- Helps to regulate calcium level in body.
- Needed for bone growth and repair.
c. VITAMIN- E
- Promotes wound healing.
- prevents tissue scarring.
- contributes to the normal structure and function of nervous system.
- functions as an antioxidant.
d. VITAMIN-K
- Required for synthesis of blood clotting proteins.
B. LIPOPROTEINS
-Transports lipids in the blood
- Carry triglycerides and cholesterol to tissues.
- Remove excess cholesterol from the blood.
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