Biochemistry: Cellular Components, Metabolism, and Molecular Genetics, Lecture notes of Biochemistry

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AN INTRODUCTION TO

BIOCHEMISTRY

PH

What is Biochemistry?

• Biochemistry is the application of chemistry to the study of

biological processes at the cellular and molecular level.

• It emerged as a distinct discipline around the beginning of the

th

century when scientists combined chemistry, physiology

and biology to investigate the chemistry of living systems by:

A. Studying the structure and behavior of the complex

molecules found in biological material and

B. How these molecules interact to form cells, tissues and

whole organism

• (^) Biochemistry is a branch of medical science that

seeks to describe the structure, organization and

functions of living matter in molecular terms.

• (^) It is the chemistry of life.

It is divided into 3 principal areas:

1. Structural chemistry

• (^) 2. Metabolism

3. Chemistry of molecular genetics

• (^) Significance: be essential to all life sciences as the common

knowledge

Genetics; Cell biology; Molecular biology

Physiology and Immunology

• (^) Pharmacology and Pharmacy
• (^) Toxicology; Pathology; Microbiology
• (^) Zoology and Botany

Agriculture

Industrial applications

• (^) Environmental implications

What is Biochemistry?

Principles of Biochemistry

 Cells (basic structural units of living organisms) are highly

organized and constant source of energy is required to

maintain the ordered state.

 Living processes contains thousands of biochemical rxns.

Precise regulation and integration of these rxns are required to

maintain life

 Certain important rxns E.g. Glycolysis is found in almost all

organisms.

 All organisms use the same type of molecules: CHO, proteins,

lipids & nucleic acids.

 Instructions for growth, reproduction and developments for

each organism is encoded in their DNA

The term Biochemistry (bios = life) was first introduced by a German

chemist Carl Neuberg in 1903

The branch of biochemistry has been variously named as Biological

Chemistry or Chemical Biology.

Modern biochemistry have two branches, descriptive

biochemistry and

dynamic biochemistry.

Descriptive biochemistry - qualitative and quantitative characterization

of the various cell components

Dynamic biochemistry - elucidation of the nature and the mechanism of

the reactions involving cell components

knowledge of biochemistry is growing speedily- newer disciplines are

emerging from the parent biochemistry.

enzymology (science of the study of enzymes),

endocrinology (science dealing with the endocrine secretions or the hormones),

clinical biochemistry, molecular biochemistry, agricultural

biochemistry, pharmacological biochemistry etc.

Philippus Aureolus Paracelsus (Lifetime or LT, 1493-1541), a Swedish

physician and chemist -laid the foundation of chemotherapy as a method

of treating diseases. He first acquired the knowledge of chemistry of his

time - then entered in the field of medicine to apply his knowledge of

chemistry.

He proclaimed, "Life processes are essentially of chemical nature and

diseases can be cured by medicines".

Scheele and Lavoisier in fact, laid down the basis of biochemistry.

Karl Wilhelm Scheele (LT, 1742 - 1786 ) discovered the

chemical composition of various drugs and the plant and animal

materials.

He isolated a number of substances such as citric acid from limejuice ,

lactic acid from sour milk, malic acid from apple and uric acid from

urine.

Antoine Lavoisier (LT, 1743-1794) developed the concept of oxidation

and also clarified the nature of animal respiration.

Lavoisier is often spoken of as 'father of modem biochemistry'.

• Louis Pasteur (LT, 1822-1895) founded the useful branch of Microbiology in

1857 and identified several organisms that carried out various fermentations,

including that leading to butyric acid , a type performed by organisms that

function without oxygen. He defined fermentation as "la vie sans I'air" (life

without air ).

• Pasteur, thus, introduced the concept of aerobic and anaerobic

organisms and their associated fermentations.

• Soren Sorensen (LT, 1868-1939), a Danish chemist, developed our concept on

pH,

• Stanley showed that viruses are nucleoproteins.

• Frederick Sanger established the complete amino acid sequence of the protein

hormone insulin.

• James D. Watson and Francis Harry Compton Crick , in 1953, proposed that a

double-stranded DNA molecule could be made by binding bases on adjacent

strands to each other by hydrogen bonding.

• 1926, James B. Sumner (LT, 1887-1955) at Cornell University, for the first time,

crystallized the enzyme urease from the extracts of Jack bean and demonstrated its

protein nature.

2. Each component unit of a living object appears to have a specific

purpose or function ,

macroscopic structure (heart, lungs, brain)

microscopic intracellular structure (nucleus).

Even the individual chemical compounds in cells (carbohydrates,

proteins, lipids) have specific functions to perform.

3. Ability to extract, transform and use energy from their

environment ,

• either in the form of organic nutrients or the radiant energy of

sunlight.

4. Capacity for self- replication , the boundary between the living and non-living

objects is not always well demarcated.

• extremely small filterable substances called viruses cause certain diseases.
• can also reproduce when introduced into the environment of living cells and a

few of them have been isolated in a purified crystalline form.

• tobacco mosaic virus (TMV) are nucleoproteins and have no apparent features

of living things. Yet TMV, - inoculated into a healthy leaf of a tobacco plant, -

multiplies rapidly, causes the onset of a disease termed tobacco mosaic disease.

8.The plant and animal worlds - indeed, all living organisms - are dependent

on each other through exchanges of energy and matter via the environment.

9.Living cells are self-regulating chemical engines, tuned to operate on the

principle of maximum economy.

10. Genetic information is encoded in units that are sub molecular in

dimensions; these units are the four kinds of nucleotides, of which DNA is

composed.

11.A living cell is self-assembling, self-adjusting, self-perpetuating isothermal

system of organic molecules which extracts free energy and raw materials from

its environment.

12. It carries out many consecutive organic reactions promoted by

organic catalysts , which it produces itself.

13.It maintains itself in a dynamic steady state , far from equilibrium with its

surroundings. It functions on the principle of maximum economy of parts and

processes.

14.Its nearly precise self-replication through many generations is ensured

by a self-repairing linear coding system.

Two notable breakthroughs

(1) Discovery of the role of enzymes as catalysts

(2) Identification of nucleic acids as information molecules

Flow of information: from nucleic acids to proteins

DNA RNA

Protein