By now, you have learnt the basic principles of

chemistry and also realised that it influences every

sphere of human life. The principles of chemistry have

been used for the benefit of mankind. Think of

cleanliness — the materials like soaps, detergents,

household bleaches, tooth pastes, etc. will come to your

mind. Look towards the beautiful clothes — immediately

chemicals of the synthetic fibres used for making clothes

and chemicals giving colours to them will come to your

mind. Food materials — again a number of chemicals

about which you have learnt in the previous Unit will

appear in your mind. Of course, sickness and diseases

remind us of medicines — again chemicals. Explosives,

fuels, rocket propellents, building and electronic

materials, etc., are all chemicals. Chemistry has

influenced our life so much that we do not even realise

that we come across chemicals at every moment; that

we ourselves are beautiful chemical creations and all

our activities are controlled by chemicals. In this Unit,

we shall learn the application of Chemistry in three

important and interesting areas, namely – medicines,

food materials and cleansing agents.

Drugs are chemicals of low molecular masses (~100 – 500u). These

interact with macromolecular targets and produce a biological response.

When the biological response is therapeutic and useful, these chemicals

are called medicines and are used in diagnosis, prevention and

treatment of diseases. If taken in doses higher than those recommended,

most of the drugs used as medicines are potential poisons. Use of

chemicals for therapeutic effect is called chemotherapy,

Drugs can be classified mainly on criteria outlined as follows:

(a) On the basis of pharmacological effect

This classification is based on pharmacological effect of the drugs. It

is useful for doctors because it provides them the whole range of

drugs available for the treatment of a particular type of problem. For

example, analgesics have pain killing effect, antiseptics kill or arrest

the growth of microorganisms.

(b) On the basis of drug action

It is based on the action of a drug on a particular biochemical process.

For example, all antihistamines inhibit the action of the compound,

histamine which causes inflammation in the body. There are various

ways in which action of histamines can be blocked. You will learn

about this in Section 16.3.2.

(c) On the basis of chemical structure

It is based on the chemical structure of the drug. Drugs classified in this

way share common structural features and often have similar

pharmacological activity. For example, sulphonamides have common

structural feature, given below.

Structural features of sulphonamides

(d) On the basis of molecular targets

Drugs usually interact with biomolecules such as carbohydrates, lipids,

proteins and nucleic acids. These are called target molecules or drug

targets. Drugs possessing some common structural features may have

the same mechanism of action on targets. The classification based on

molecular targets is the most useful classification for medicinal chemists.

Macromolecules of biological origin perform various functions in the

body. For example, proteins which perform the role of biological catalysts

in the body are called enzymes, those which are crucial to

communication system in the body are called receptors. Carrier proteins

carry polar molecules across the cell membrane. Nucleic acids have

coded genetic information for the cell. Lipids and carbohydrates are

structural parts of the cell membrane. We shall explain the drug-target

interaction with the examples of enzymes and receptors.

(a) Catalytic action of enzymes

For understanding the interaction between a drug and an enzyme,

it is important to know how do enzymes catalyse the reaction

(Section 5.2.4). In their catalytic activity, enzymes perform two

major functions:

(i) The first function of an enzyme is to hold the substrate for a chemical

reaction. Active sites of enzymes hold the substrate molecule in a

suitable position, so that it can be attacked by the reagent effectively.

Substrates bind to the active site of the enzyme through a variety

of interactions such as ionic bonding, hydrogen bonding, van der

Waals interaction or dipole-dipole interaction

The second function of an enzyme is to provide functional groups

that will attack the substrate and carry out chemical reaction.

(b) Drug-enzyme interaction

Drugs inhibit any of the above mentioned activities of enzymes. These

can block the binding site of the enzyme and prevent the binding of

substrate, or can inhibit the catalytic activity of the enzyme. Such

drugs are called enzyme inhibitors.

Drugs inhibit the attachment of substrate on active site of enzymes

in two different ways;

(i) Drugs compete with the natural substrate for their attachment

on the active sites of enzymes. Such drugs are called competitive

Some drugs do not bind to the

enzyme’s active site. These bind

to a different site of enzyme

which is called allosteric site.

This binding of inhibitor at

allosteric site (Fig.16.3) changes

the shape of the active site in

such a way that substrate can-

not recognise it.

If the bond formed between

an enzyme and an inhibitor is

cannot

cannot be broken easily, then the enzyme is blocked permanently.

The body then degrades the enzyme-inhibitor complex and

synthesises the new enzyme.

Receptors are proteins that are crucial to body’s communication

process. Majority of these are embedded in cell membranes (Fig.

16.4). Receptor proteins are embedded in the cell membrane in such

a way that their small part possessing active site projects out of the

surface of the membrane and opens on the outside region of the cell

membrane (Fig. 16.4).

16.2.2 Receptors

as Drug

Targets

Fig. 16.4

Receptor protein

embedded in the cell

membrane, the

active site of the

receptor opens on

the outside region of

the cell.

The day of 15th August 1947 has been embossed in the golden history of India. It is the day when India got its freedom from 200 years of British rule. It was a hard and long struggle in which many freedom fighters and great men sacrificed their lives for our beloved motherland.

India celebrates its Independence Day on the 15th of August every year. However, this year, the auspicious day is being celebrated as ‘75 Azadi Ka Amrit Mahotsav 2022’ to commemorate 75 long years of India’s independence. Independence Day, called the Red-Letter Day in the history of our country, is celebrated as a national holiday throughout India.

Independence Day 2022 helps us remember every one of the penances our political dissidents made to liberate India from British rule. On 15th August 1947, India was announced free from British imperialism and turned into the biggest vote-based system, the largest democracy in the world.

In this essay on Independence Day, students can track down every one of the significant subtleties of India's Independence history. They can allude to it for their exam preparation as papers are generally asked in the CBSE English paper. Additionally, they can utilise this article as study material for the Independence Day essay for kids during the exam.

15th August is commended as a public celebration with flag hoisting, marches, and social works. Schools, universities, workplaces, society buildings, government, and private associations celebrate this day beautifully. On this day, the Prime Minister of India hoists the National Flag at the Red Fort and addresses the country with a speech. Doordarshan communicates the whole occasion in real-time on TV.

In 1947, on 15th August, India became independent. We won freedom from British Raj after a hard struggle. On this day at the stroke of midnight, Pandit Jawaharlal Nehru, our first Prime Minister, unfurled the National Flag at the Red Fort for the first time. It marked the end of the 200 years old British reign in India. We now breathe air in a free and sovereign nation.

The British have governed India for about 200 years. Under British colonisation, the life of every Indian was dismal and full of struggle. Indians were treated as slaves and had no freedom of speech. Indian rulers were puppets in the possession of British officers. Indian fighters were dealt with cruelty in British camps, and farmers were starving as they couldn't grow crops and needed to pay substantial land taxes.

On this special occasion, the people of India remember the selfless sacrifices and unparalleled contributions of great men and women to achieve the independence of India. Leaders like Mahatma Gandhi, Jawaharlal Nehru, Subhas Chandra Bose, Maulana Abdul Kalam Azad, Sardar Patel, and Gopalbandhu Das are paid reverent homage by one and all in the country.

India couldn't have acquired independence without the efforts of numerous extraordinary freedom fighters. Bhagat Singh, Rani of Jhansi, Chandra Shekhar Azad, Subhas Chandra Bose, Mohandas Karamchand Gandhi, Jawaharlal Nehru, Ram Prasad Bismil, and Ashfaqulla Khan are some of the notable names.

Several women have played a significant part in the Indian freedom movement. Savitribai Phule, Mahadevi Verma, Capt Laxmi Sehgal, Rani Laxmibai, and Basanti Devi are just a few crucial names to remember. These women along with many others played a prominent role in leading India towards its independence.

Not all the British were awful; many started adoring India and did incredible things for it. Some even took part in the Indian Independence struggle. Some of the good British rulers include Warren Hastings who developed court reforms; Freda Bedi who supported Indian nationalism; Allan Octavian Hume who started the Indian National Congress, etc.

India accomplished freedom following a 200-year-long battle. India gained complete independence from the British on 15th August 1947. That is why the day holds importance in the heart of each Indian citizen either living in India or abroad. India is celebrating 75 years of freedom on 15th August 2022 as Azadi Ka Amrit Mahotsav. This day also helps us remember the struggles of freedom fighters and the lives

The struggle that our freedom fighters have gone through shows us that the freedom we appreciate today has been attained by shedding the blood of hundreds of individuals. It stirs patriotism inside each Indian. It makes the current generation understand the struggles of individuals around them and familiarise themselves with the freedom fighters of India.

Independence day is a positive historical event for the country since we were free from British rule on this day. It unites diverse individuals all over the country. Unity in diversity is the fundamental path and strength of India. We feel pleased to be a part of the biggest majority-rule country on the planet, where we live in a democracy.

Independence Day is an important day in the life of every Indian citizen. Year after year, it reminds us of our great freedom fighters who sacrificed and struggled their lives in order to free our Motherland from British rule. It reminds us of the great paragons, which were the foundation of the dream of a free India, envisioned and realised by the founding fathers.

Independence Day is celebrated with great joy across the country. People hold meetings, fly the tricolour flag, and sing the National Anthem. There is great enthusiasm among all. In the national capital, Delhi, this day is celebrated with great pomp and show. All leaders and common people gather in large numbers on the parade ground in front of the Red Fort and eagerly wait for the arrival of the Prime Minister.

The Prime Minister then  hoists the National Flag and makes a speech that focuses on the achievements of the government during the past year, mentions the issues that still need to be addressed, and calls upon further developmental efforts. Foreign dignitaries are also invited to this occasion.

Tributes are paid to the freedom fighters who sacrificed their lives during the struggle. The Indian National Anthem – “Jana Gana Mana” is sung. The parade by the Indian Army and the Paramilitary forces is followed by the speech. All state capitals hold events on similar lines with the Chief Minister of the respective states unfurling the National Flag.

26th January is celebrated as Republic Day in our country. On this day in 1950, the constitution of our country was formally adopted and India became a fully sovereign state. The fundamental law of the country, the Constitution, was enacted out of the diligence and hard work of great men like Mahatma Gandhi and the numerous freedom fighters who fought and sacrificed their lives for the independence of our country. So, the 26th of January was declared a National holiday and has been recognized and celebrated as the Republic Day of India ever since.

After Independence, the country did not have any self-made official Constitution, instead, its laws were based on modified colonial acts. So, establishing an official constitution for our own country was the utmost task in front of the Government of India. Our constitution is the result of the hard work and struggle of the esteemed members of the Constituent Assembly under the Presidency of Dr. Rajendra Prasad. Dr. Ambedkar was the Father of our Constitution. After deeply studying the various constitutions of other countries, our founding fathers framed our Constitution and it is the lengthiest constitution in the world. It reflects upon the dedication and foresight of these great men. That is how the Constitution came into being. It took two years, eleven months, and eighteen days to complete the Constitution. Though it was enacted and adopted by the constituent assembly on 26th November 1949, it came into force on 26th January, 1950.

After Independence, the country did not have any self-made official Constitution, instead, its laws were based on modified colonial acts. So, establishing an official constitution for our own country was the utmost task in front of the Government of India. Our constitution is the result of the hard work and struggle of the esteemed members of the Constituent Assembly under the Presidency of Dr. Rajendra Prasad. Dr. Ambedkar was the Father of our Constitution. After deeply studying the various constitutions of other countries, our founding fathers framed our Constitution and it is the lengthiest constitution in the world. It reflects upon the dedication and foresight of these great men. That is how the Constitution came into being. It took two years, eleven months, and eighteen days to complete the Constitution. Though it was enactedand adopted by the constituent assembly on 26th November 1949, it came into force on 26th January, 1950

It is to be noted that January 26 had a great significance in India’s struggle for Swaraj. The Congress Session at Lahore on December 29, 1929, had passed a resolution declaring Purna Swaraj (Complete Independence) as India’s goal. It was also decided that the 26th of January should be observed all over India as Purna Swaraj Day. The complete Independence Day was for the first time celebrated on January 26th, 1930. It continued to be so observed until 1947. On achieving Independence, August 15 became our Independence Day.

January 26th, however, marked a great event in India’s struggle for freedom. It was, therefore, in the favour of all that January 26 should be selected as the Date of Commencement of the new Constitution.Therefore, this day is celebrated as a day of national significance with great joy and pride.

Indians celebrate Republic Day with great jubilation and joy all over the country. The day honours India's constitution as an independent nation. Schools and colleges hoist the national flag on Republic Day. Cultural events celebrating India's struggle for independence are organised across the country. The President of India hoists the national flag at India Gate in New Delhi. In New Delhi, the most prestigious parade takes place on Rajpath. An Indian President conducts the parade, which is coordinated by the Ministry of Defence. The event not only displays India's military prowess but also promotes its diverse culture. In addition, the event pays tribute to those who have

sacrificed their lives for the country. India's Prime Minister honours the martyrs by placing a ringlet at India Gate's Amar Jawan Jyoti. The ceremony continues with a 21-gun salute, national anthem, and hoisting of the national flag. As a result, the brave soldiers are presented with the Paramvir Chakra, Ashok Chakra, and Vir Chakra. Children and ordinary citizens who have shown courage in difficult circumstances are also recognized with awards.

Those who receive a gallantry award salute the President in gratitude. Then, India's military prowess is on display. There is also a march-past that the armed forces, police, and National Cadet Corps take part in, during which the President of India is saluted by these regiments. When the fighter jets of the Indian Air Force fly past Janpath, the ceremony concludes. The Republic Day celebrations are held across the country, but Delhi is the centre of the largest celebration. Every year, millions of people have the opportunity to watch a live Webcast of the Republic Day Parade. 'Video on demand' is made available after the event as a way to view the exclusive footage. The flag is also unfurled in the state capitals, though on a smaller scale, where the Governor unfurls the flag. At district headquarters, subdivisions, talukas, and panchayats, the celebrations take place in a similar manner.

The official end to the Republic Day celebrations is Beating the Retreat, which takes place after all of the celebrations are over. From 26th to 29th, the government buildings are beautifully lit in glittering lights. On January 29, the third day after Republic Day, the beating retreat ceremony is held. During the Drummer's Call, drummers perform solo performances. The bands march back playing the popular martial tune, Saare Jahan Se Achcha. At exactly 6 p.m., the National Flag is lowered and the National Anthem is sung, marking the end of Republic Day celebrations.

Republic Day is celebrated with much enthusiasm in India, and we should remember the long journey to freedom and the struggles of our forefathers to transform the country into a sovereign nation. It is a day for all Indians to celebrate the essence of liberty and help India accomplish its freedom fighters' dreams. In celebration of Republic Day, citizens are encouraged to display their patriotism and pride. The students pledge to live as good citizens and help make their country a happier and more peaceful one.