Biomolecules are also called the “chemicals of life”. These chemicals form a system which makes up the living things more complex.the are several huge molecules called macro-molecules made up of many simple molecules .these chemicals perform the metabolic activities of the living beings. They can act as catalyst in these processes as enzymes. They form the structure of the organisms.


The term lipid was coined by BLOOR

Lipids include a variety of molecular types, such as neutral fats, oils, steroids, and waxes. Unlike other classes of biomolecule, lipids do not form large polymers. Two or three fatty acids are usually polymerized with glycerol, but other lipids, such as steroids, do not form polymers.

Characteristics of Lipid:

General characters of lipids are:

Lipids are relatively insoluble in water.

They are soluble in non-polar solvents, like ether, chloroform, methanol.

Lipids have high energy content and are metabolized to release calories.

Lipids also act as electrical insulators, they insulate nerve axons.

Fats contain saturated fatty acids, they are solid at room temperatures. Example, animal fats.

Plant fats are unsaturated and are liquid at room temperatures.

Pure fats are colorless, they have extremely bland taste.

The fats are sparingly soluble in water and hence are described are hydrophobic substances.

They are freely soluble in organic solvents like ether, acetone and benzene.

Properties of lipids:

Hydrolysis: Lipids act as efficient catalyst in alimentary canal of animal for hydrolysis ester bonds releasing 3 molecules of fatty acids and 1 molecule of glycerol.

Saponification: When boiled with Na or K hydroxides ,fats are hydrolysed to into Na or K salts of long chain fatty acids which are called long chains of fatty acids called soaps and the hydrolysis is called saponification. The soaps so formed are used for cleaning.

Dehydration :when heated with Sodium hydrogen sulphide OR Potassium hydrogen sulphide the glycerol in it is dehydrated to an unsaturated aldehyde called acrylic .It confirms the presence of glycerol in a fat.

Hydrogenation:on catalytic hydrogenation at low pressure ,hydrogen ads across C=C of the acid components of the tri glycerol.


Proteins are large, complex molecules that play many critical roles in the body. They do most of the work in cells and are required for the structure, function, and regulation of the body’s tissues and organs.

Proteins are made up of hundreds or thousands of smaller units called AMINO ACID, which are attached to one another in long chains. There are 20 different types of amino acids that can be combined to make a protein. The sequence of aminoacids determines each protein’s unique 3-dimensional structure and its specific function .Mostly proteins are made up of 20 base proteins called MAGIC 20.

Classifications of Amino Acid:

Experts classify amino acids based on a variety of features, including whether people can acquire them through diet.

Accordingly, scientists recognize three amino acid types:


2 -Essential

3-Conditionally essential

Histidine is an amino acid that is categorized as semi-essential since the human body doesn’t always need it to properly function; therefore, dietary sources of it are not always essential. Meanwhile, conditionally essential amino acids aren’t usually required in the human diet, but do become essential under certain circumstances. Essential amino acids or from normal protein breakdowns. Nonessential amino Finally, nonessential amino acids are produced by the human body either from acids include:




4-Aspartic acid


6-Glutamic acid





An additional Amino acid classified  as  the side chain structure that divides the list of 20 amino acids into four groups – two of which are the main groups and two that are subgroups. They are:



acidic and polar

Basic and polar

For example, side chains having pure hydrocarbon alkyl or aromatic groups are considered non-polar, and these amino acids are comprised of Phenylalanine, Glycine, Valine, Leucine, Alanine, Isoleucine, Proline, Methionine, and Tryptophan. Meanwhile, if the side chain contains different polar groups like amides, acids, and alcohols, they are classified as polar. Their list includes Tyrosine, Serine, Asparagine, Threonine, Glutamine, and Cysteine.

Physical properties : protiens show properties like colloidal effect ,tyndall effect, denaturation, renaturation or refolding etc


Chemical properties:protiens react with millons reagent,follins reagent, undergo hydrolysis,nin hydrin reaction etc.



Carbohydrate is a biological molecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water); in other words, with the empirical formula Cm(H2O)n (where m could be different from n).This formula holds true for monosaccharides. Some exceptions exist; for example, Deoxyribose, a sugar component of DNA,[2] has the empirical formula C5H10O4. Carbohydrates are technically hydrates of carbon; structurally it is more accurate to view them as polyhydroxy aldehydes and ketones.





Oxidation:with mild agents like HOBr,glucose is oxduised to gluconic acid.This reaction is used to distinguish aldoses from ketoses.

They also under go reactions with schiffs reagent ,tollens reagent,molins reagent.


They are organic micronutrient and can not be synthesized by the body and have to be supplemented .their deficiency may cause diseases.they are of two kinds 1)fat soluble- vitamin A,D,E,K 2)water soluble –vitamin B,C


Maintains the growth of human body .

Regulates Ca and PO4 metabolism.

Functions as anti oxidant

Its soiurces are milk ,butter, tomato, leafy vegetable.


Nucleic acids

Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are made up of nucleic acids found in the nuclei of living cells. They are the vehicles of genetic inheritance.

Nucleic acids are condensation polymers of nucleotides.The nucleotide consists of a phosohate group,a pentose sugar ,and anitrogen containing base (thymine,cytocyne or uracil,adnine,guanine).


DNA is the cellular molecule that contains instructions for the performance of all cell functions. When a cell divides, its DNA is copied and passed from one cell generation to the next generation.

DNA is organized into chromosomes and found within the nucleus of our cells. It contains the “programmatic instructions” for cellular activities. When organisms produce offspring, these instructions in are passed down through DNA. DNA commonly exists as a double stranded molecule with a twisted double helix shape.

DNA is composed of a phosphate-deoxyribose sugar backbone and the four nitrogenous bases: adenine (A), guanine (G), cytosine (C), and thymine (T). In double stranded DNA, adenine pairs with thymine (A-T) and guanine pairs with cytosine (G-C)

Ribose nucleic acid

RNA stands for ribonucleic acid. It is an important molecule with long chains of nucleotides. A nucleotide contains a nitrogenous base, a ribose sugar, and a phosphate. Just like DNA, RNA is vital for living beings. RNA is formed from DNA by a process called transcription. This uses enzymes like RNA polymerases. RNA is central to protein synthesis. First a type of RNA called messenger RNA (mRNA) carries information from DNA to structures called ribosomes. These ribosomes are made from proteins and ribosomal RNAs (rRNAs). These all come together and form a complex that can read messenger RNAs and translate the information they carry into proteins. This requires the help of transfer RNA or tRNA.


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