Notes of Biol-Chemistry

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LIPIDS
 
LIPIDS
Lipids are naturally accruing organic compounds which are soluble in BLOOR'S REAGENT.
Bloor's reagent is a mixture of diethyl ether and ethyl alcohol. Generally lipids are fats and fat like compounds and they contain mostly carbon , hydrogen and oxygen.
TYPES OF LIPIDS
 There are three classes of lipids:
 1. Simple lipids
 2. Compound lipids
 3. Steroids
SIMPLE LIPIDS
 Naturally occurring oils, fats and waxes are collectively known as " simple lipids". Simple lipids are the  esters of long chain fatty acids with alcohols.
FATS AND OILS
 Natural fats and oils are the Esters of glycerol with long chain carboxylic acid (12 to 20 carbon  atoms).These are known as triglycerides or triacylglycerols.

DIFFERENCE BETWEENFATS AND OILS
 Both fats and oil are belong to the class of esters known as glycerides or triglycerides but main difference  between them is that oils are liquid at room temperature (20OC) while fats are solids or semi solids at room  temperature. Oils contain higher proportion of glycerides of unsaturated fatty acids while fats contain high  proportion of saturated.
 Examples of oils: oleic acid, linolenic acid, linoleic acid
 Examples of fats: Palmitic acid, staeric acid
DRYING OIL
 Drying oils are those that contains large no of glycerides of unsaturated fatty acids as Linoleic acid
 and lanolenic acid. Drying oils when exposed to air , they undergo oxidation and double bonds open up  forming peroxides which then polymerize to from a dry, hard and tough film.
NON DRYING OIL:
 Non drying oils contain negligible amount of glycerides of unsaturated fatty acids
RANCIDIFICATION
 When oils and fats are exposed to warm and moist air for a long time they give off offensive odor and  become off-tastes. This process is called Rancidification. Rancidification caused by the hydrolysis of ester  linkage or oxidation at double bond forming volatile aldehydes or bad smell.
WAXES
 Naturally occurring esters of long-chain carboxylic acids with long- chain alcohols are called wax. Waxes are low melting  point solids with waxy feeling.
TRUE WAX
 True waxes are simple lipids
 Example:

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NON TRUE WAX
 Non true waxes are the esters of cholesterol, vitamin A & D
COMPOUND LIPIDS
 These are the esters of glycerol with two saturated or unsaturated fatty acids and some other compound  such as carbohydrate, amino acid or amine derivative, phosphoric acid or protein etc. They are also known  as complex or conjugated lipids.
 Example: lecithin, cephalins, sphingomelins etc.
STEROIDS
 Steroids are non-saponfiable lipids that contain polycyclic structures in their molecule. Steroids can not be  hydrolysed by strong base.
 Some of the common steroids are:
 Cholesterol, cholic acid, progesterone,
1. CHOLESTEROL
 It is the most common steroid found virtually in animal tissues, in blood, in brain and in spinal column.  Cholesterol is a yellowish wax like substance closely related to fats. It deposits in arteries to elevate blood  pressure causing heart attack.
2. COLIC ACID
 It is a derivative of cholesterol. Its sodium salt is found in bile. It is an enzymes , it breaks down fats into  fatty acids.
3. PROGESTERONE
 This steroid controls the sexual development and functioning of body
FATTY ACIDS
 Fatty acids are naturally occurring long chained saturated or unsaturated carboxylic acid with 12 to 20  carbon atoms. They are obtained by the hydrolysis of fats and oils.
 Example: Palmitic acid, Stearic acid, linoleic acid etc.
ESSENTIAL FATTY ACIDS
 Fatty acids which are unsaturated containing carbon-carbon double bond and cannot be synthesized in  animal body are known as essential fatty acids.
 Example:
 Linolenic acid (C17H29COOH)
 Linoleic acid (C17H31COOH)
 Arachidonic acid (C19H31COOH)


FUNCTION OF ESSENTIAL FATTY ACIDS
 They prevent deposition of cholesterol in arteries and veins.
 They help in reproduction function and blood clotting.
 Their deficiency results loss of weight in children .
 Their deficiency results in the development of eczema.

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ENZYMES
ENZYMES
A class of proteins which catalyze all types of biochemical reactions such as digestion, respiration , metabolism contraction take place in the living organism are known as Enzymes. These biological catalysts do not only accelerate the rate of reaction but also drive a reaction to completion which normally occur t room temperature . All biological reaction are enzymes catalyzed.
NOMENCLATURE
The word ENZYME consists of two words:
1) Suffix of enzymes.:ASE
2)Prefix of enzyme: Name of Subtract Or type of action
For example:
Dehydrogenase: dehydrogenation enzyme.
CLASSIFICATION OF ENZYMES
OXIDO- REDUCTASE
These enzymes catalyze oxidation and reduction reactions is called oxido-reductase.
 
TRANSFERASE
These enzymes catalyze the reaction of group transfer from subtract to another.
L- Aspartic acid + 2 oxoglutaric acid---(aspartate amino transferace)--->- oxaloacetate+Glutamic acid
HYDROLASES
These enzymes catalyze hydrolytic reactions.
Amylose---------------(amylase)-------------------> glucose
Lipids ---------------(lipase)-------> Fatty acids + glycerol
Proteins ---------------(protease)------------> Amino acids
LAYASES
These enzymes catalyze the addition of groups to double bond or vice versa.
Threonine ----------(Threonine aldolase)---------> glycine + acetaldehyde
ISOMERASE
These enzymes catalyze the reaction of isomerization
L- alanine -----(alanine resmerase)----->-D- alanine
LIGASES
: These enzymes catalyze the reaction of condensation of two molecules.

PROPERTIES OF ENZYMES
1. enzymes in aqueous solution kept for a long time lose their activity.
2. they become inactive by any treatment that coagulate protein material.
3. Excessive heat. Alcohol, salts of heavy metals and concentrated solutions of mineral acids will stop the activity of an enzyme.
FACTORS AFFECTING RATE OF ENZYME ACTION
1. Temperature:
Optimum activity of enzymes lies between 37oC to 50oC, beyond this temperature range they lose their activity
However at lower temperature they do not lose their activity .
PH:
Every enzymes is active at a certain pH. For example optimum pH for pepsin 1.6 and for trypsin it is 8.2.
ENZYMES CONCENTRATION
An increase in concentration of an enzyme generally increases the rate of reaction.
Other factors:
Other factors are substrate concentration , nature of products and presence of ions.

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VITAMINS
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VITAMINS
Vitamins are defined as " the organic substances which are necessary food factors required in small amounts to regulate energy transformation and metabolism. Vitamins are not energy source but they also work as food catalysts too. Vitamins are effective in very small amounts (milligrams or micrograms). Every vitamin has a specific function and deficiency of a particular vitamin in diet causes a specific disease. Vitamins are not formed in the body except vitamin D.
CLASSIFICATION OF VITAMINS
According to their solubility, vitamins are divided into two classes:
1. WATER SOLUBLE VITAMINS : Vitamin B- complex , Vitamin C
2. FAT SOLUBLE VITAMINS : Vitamin A, Vitamin D,Vitamin E and Vitamin K
VITAMIN A (Retinol)

FOOD SOURCES
Fats of milk, egg, liver fats, cod liver oil, carrot, butter, green vegetable , cheese etc.
FUNCTION
1. The main function of vitamin A" is to form VISUAL PIGMENT. Healthy teeth, saves from infectious diseases, softness of tissues .
2. It transports nutrients across the cell membrane.
SYMPTOMS DUE TO DEFICIENCY
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1. Night blindness leads to xerophthalmia .
3. Infectious diseases.
RDA (recommended daily allowance) : 1000 microgram
VITAMIN B- COMPLEX
B- complex is a group of 12 vitamns such as:
 Vitamins B1 (Thiamine)
 Vitamins B2 (Riboflavin )
 Vitamin B5 ( Niacin)
 Vitamins B6 pyridoxine )
 vitamin B12 (cyano cobaltamine)
 lipoic acid
 Biotin acid
 Folic acid
 Inosital
 Panothenic acid.
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VITAMIN B1 ( THIAMIN )
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.
FOOD SOURCES
Liver, kidney, cereal, nuts, eggs yolk, legumes, fish, meat, fruits etc.
FUNCTION
It helps body cells to convert carbohydrates into energy.
Healthy heart function.
Healthy nerve cells .
Brain functioning.
DISEASES
Beri Beri , heart failure, Loss of weight, digestive disturbance, weakness , nerve damage, constipation

R.D.A
1.1 to 1.5 mg
Note
Improper cooking and too much washing can lose the activity of this vitamin.

VITAMIN B2( RIBOFLAVIN )
.
FOOD SOURCES
Milk, egg, liver, fish, yeast, fruits, green leafy vegetables, wheat , pea, soybean.
FUNCTIONS
Body growth, red cell production, helper for other B- vitamins
DISEASES
Dry & cracked skin, inflammation on mouth, anemia, eye diseases, poor general health, scales on nails.
R.D.A
1.3 to 1.7 mg
Note
It is light ( sun light ) sensitive
VITAMIN B6 ( PYRIDOXINE )
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FOOD SOURCES
Milk, liver, yeast, green leafy vegetables , cereals, kidney, fish, eggs, nuts etc.
FUNCTIONS
Protein and fatty acid metabolizer
Red cells production.
Brain function.
Helps to synthesize antibodies.
DISEASES
Skin disorders, digestive problems, anaemia
R.D.A
2.2 mg
Note
It is Sensitive to sun light air and heat.
Large dosages can lead to neurological disorders.
NICOTINIC ACID
( NIACIN )
.
FOOD SOURCES
Red meat, liver, yeast, peanut, fish, eggs etc.
DEFICIENCY PROBLEMS
Mental disturbances
Diarrhoea
Pellagra
Skin lesions.
R.D.A
More details
14 mg to 19 mg
Note
It is stable towards heats light acid & alkalis.