Introduction to Biochemistry

BIOCHEMISTRY

· What is the Biochemistry?

· History and development

· How to study Biochemistry?

Definition: The chemistry of life;

· The science concerned with the chemical basis of life.

· The science concerned with the various molecules that occur in living cells and organisms and with their chemical reaction.

· Anything more than a superficial comprehension of life – in all its diverse manifestation - demands knowledge of biochemistry.

Organic Chemistry: It is a science that deals with the organic compounds found in the nature. Biochemistry is thus a branch of organic chemistry which deals with the organic compounds within the living systems. Biochemistry deals with the structural, functional and dynamic roles of biomolecules in depth.

Definition: 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 20th 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. the ways these molecules interact to form cells, tissues and whole organism

Aim of Biochemistry:

Biochemistry describes structure, function and organization of cell in molecular terms, and explains all chemical processes of living cells

· Structure-function

· Metabolism and Regulation

· Molecular Genetics

History of Development of Biochemistry:

· Vital forces in early part of 19^th century: The vital force stated that the vital forces exist only to living organisms. According to the theory, the compounds found in living organisms cannot be synthesized in the lab. They are only found in living systems. The theory existed for a longer period and was disproved in half of 19^th century.

· 1828 Friedrich Wohler: F. Wohler in1828 disproved the vital force theory. Urea was synthesized by heating the inorganic compound ammonium cyanate (1828). This showed that compounds found exclusively in living organisms could be synthesized from common inorganic substances

Ammonium cyante + heat ® Urea

1897 Eduard Buchner: E. Buchner fermented alcohol from glucose and dead yeast in lab in 1897. It showed that living organisms are not required for fermentation. The products from living organisms are sufficient to carry out chemical reactions. He showed the role of enzymes in fermentation.

Glucose + Dead Yeast ® Alcohol

· 1903, Neuberg (German): He defined the term “Biochemistry” as the “Chemistry of Life”

Two notable breakthroughs in history of Biochemistry are;

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: The flow of information from nucleic acids to proteins take place by transcription and translations processes.

_{Transcription} _Translation

DNA ® RNA ® Protein

Krebs in 1937: In 1937， Krebs for the discovery of the Citric Acid Cycle-won the Nobel Prize in physiology or Medicine in 1953.
1944 Avery, MacLeod and McCarty: They identified DNA as information molecules
In 1953，Watson & Crick: Watson and Crick proposed the “DNA Double Helix” model by X-ray crystallography and won the Nobel Prize in Physiology or Medicine in 1962.
In 1955，Sanger: Sanger determined the insulin sequence and won the Nobel Prize in Physiology or Medicine in 1956
In 1980， Sanger & Gilbert: They discovered the methods for sequencing of DNA and won the Nobel Prize in Chemistry in 1980.
In 1993, Kary B. Mullis: Kary B. Mullis invented PCR method and won the Nobel Prize in Chemistry in 1993

Evolution of Earth

Big bang theory

• Cataclysmic explosion

• All the matter in the universe was originally confined to a comparatively small volume of space.

• Late started explosion and spread

• Volume expanded and exploded into many pieces in the universe

• Early universe contains only H, He and Le

Rest of the chemicals are thought to have been formed in three ways

1. the thermonuclear reactions in stars

2. explosion of stars

3. action of cosmic rays outside the stars

Radioactive dating

• The age of the Earth=4-5 billion

• No free 0₂ in the early stages

• UV irradiation

• No 0₃ layer in the Earth

• Only the gases present are NH₃, H₂S, CO, CO₂, CH₄, N₂, H₂

Structural hierarchy of an organism:

Elements

Simple organic compounds (monomers)

Macromolecules (polymers)

Supramolecular structures

Organelles

Cellss

Tissues

Organisms

Figure: Structural hierarchy of an organism

Biomolecules

Just like cells are building blocks of tissues likewise molecules are building blocks of cells.
Animal and plant cells contain approximately 10, 000 kinds of molecules (bio-molecules)
Water constitutes 50-95% of cells content by weight.
Ions like Na⁺, K⁺ and Ca⁺² may account for another 1%
Almost all other kinds of bio-molecules are organic (C, H, N, O, P, S)
Infinite variety of molecules contain carbon, C.
Most bio-molecules considered to be derived from hydrocarbons.
The chemical properties of organic bio-molecules are determined by their functional groups. Most bio-molecules have more than one.
Organic compounds are compounds composed primarily of a Carbon skeleton.
Carbon is more abundant in living organisms than it is in the rest of the universe.
What makes Carbon Special? Why is Carbon so different from all the other elements on the periodic table?
The answer derives from the ability of Carbon atoms to bond together to form long chains and rings.

Small molecules:

• Lipid, phospholipid, glycolipid, sterol,

• Vitamin

• Hormone, neurotransmitter

• Carbohydrate, sugar

Monomers:

• Amino acids

• Nucleotides

• Monosaccharides

Polymers:

• Peptides, oligopeptides, polypeptides, proteins

• Nucleic acids, i.e. DNA, RNA

• Oligosaccharides, polysaccharides (including cellulose)

Different functional groups in Biomolecules:

All cells share some common characteristics:

All cells use nucleic acids (DNA) to store information

Except RNA viruses, but not true cells (incapable of autonomous replication) .

All cells use nucleic acids (RNA) to access stored information
All cells use proteins as catalysts (enzymes) for chemical reactions

A few examples of RNA based enzymes, which may reflect primordial use of RNA

All cells use lipids for membrane components

Different types of lipids in different types of cells

All cells use carbohydrates for cell walls (if present), recognition, and energy generation

Scope of Biochemistry: It is 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

Clinical Biochemistry:

Medical students who acquire a sound knowledge of Biochemistry will be in a strong position to deal with two central concerns of the health sciences:

(1) The understanding and maintenance of health

(2) The understanding and effective treatment of disease

· Causes of cancers

· Molecular lesions causing various genetic diseases

· Rational design of new drugs

Industrial Biochemistry:

Fermentation technology and many food industries require knowledge on Biochemistry. They are working as quality controller in many industries. Without knowledge on Biochemistry, no good quality of products can be obtained. E.g. wine and alcohol production

· Beverage: breads and CO₂

· Drug and food supplements

· Organic compounds used as substrate

Nutritional Biochemistry:

· Calculation of energy

· Balanced diet

· Diet for patients:

§ enzymes for gastric patients or metabolic disorder problems

§ Insulin for Diabetic patients

§ HDL foods for heart disease patients

Agricultural Biochemistry:

· Livestock and animal husbandry