Introduction to Biochemistry
*Principles, basic Concepts & Historical perspective
Water: The molecule of life
* Physical & Chemical Properties
COURSE TITLE: BIOCHEMISTRY 1
COURSE CODE: BCHT 201
PLACEMENT/YEAR/LEVEL: 2nd Year/Level 4, 1st Semester
M.F.Ullah, Ph.D
Showket H.Bhat, PhD
What is Biochemistry ?
Definition:
Biochemistry (or biological chemistry) is the study of chemical processes
in living organisms; the prefix bio- comes from bios, the Greek word for “life”.
Chemistry is the branch of science that deals with chemical
Reactions.
In short Biochemistry is the study of chemical reactions involved in life processes such as:
i. Making up the structure of a living organism
Organic molecules-------- Cells-------tissues--------organs------Organism
ii. Carrying out the function of various components of a living organism
Mitochondrion---------energy production
iii. Mechanisms of growth and reproduction in a living organism
cell cycle ( cell division)
iv. Fulfilling the energy requirements of a living organism
metabolic pathways (glycolysis, Kreb’s Cycle)
Application of Biochemistry:
Biochemistry is a basic science that finds a vast range of application in varied fields
such as:
i.
Medicine: Biochemistry is useful in understanding the diseases and development
of drugs
ii. Agriculture: Plants being living system the biochemical processes in plants are used
to enhanced the crop productivity and quality of yeild e.g. genetically modified foods
(GMF)
iii. Nutrition: The value of different food items (plants/animal based) can be examined
and their suitability for nutrional benefits is assessed.
iv. Industry: 1. The pharmaceutical industry greatly relies on biochemistry because the
chemical make-up of the body must be studied in relationship to the chemicals we use
as drugs. For example, antidepressants like Prozac, called serotonin reuptake inhibitor
(SSRIs), is used because there is an underlying medical assumption that in depressed
people, serotonin gets used too quickly by the body. This affects mood significantly. By
inhibiting the body’s quick consumption for serotonin, more free serotonin is allowed
to circulate and thus improves depression. 2. Food Industry: Probiotics , health drinks,
artificial sweetner.
Principles of Biochemistry
1. Living processes contain thousands of chemical pathways. The chief goal of
biochemistry is to understand the structure and behavior (chemical reactions) of biological
molecules involved in these pathways.
2. The biological molecules which biochemistry is concerned with are carboncontaining compounds that:
(i) make up the various parts of the living cell and
(ii) carry out the chemical reactions that enable it to grow, maintain and reproduce itself, and
use and store energy.
A vast array of biological molecules is present in the cell. Among the most important classes of
biological molecules are carbohydrates, proteins, lipids and nucleic acids.
3.Living organisms are enormously diverse (different). In appearance and function,
birds and fishes, trees and elephants, rats and humans differ greatly. However, all organisms
are remarkably alike (unified) at cellular and chemical levels. E.g 1. structural and functional
units of cell use the same type of molecules: carbohydrates, proteins, lipids & nucleic
acids. 2. Fundamnetal energy processes are similar such as glycolysis
4. Specific biochemical adaptations help the organism to survive in a specific
environment. E.g. Thermophilic bacteria (hot spring) and halophiles (salty
environment)
5. Instructions for growth, reproduction and developments for each organism is
encoded in their DNA (genetic material)
Biochemical terminologies & processes
Cell: A cell is the building block of life. All living organisms are made up of cells.
Biomolecules: The components of a cell related to its structure and function are made
up of chemical complexes of carbon and hydrogen. These hydro-carbon compounds in
living cells are called biomolecules. There are four classes:
1. Carbohydrates:
Carbohydrates are the basic fuel molecules of the cell. It may break them down to yield
chemical energy or use them as raw materials to produce other molecules. E.g. glucose
2. Proteins:
Proteins are large molecules built up of small subunits called amino acids. The proteins
are of greatest interest within the cell since it (1) participate in the building of cell
structure. e.g. actin/myosin (muscle protein) and (2) responsible for the cellular
functions as biocatalysts molecules (enzymes).
3. Lipids:
Lipids are fatty substances that play a variety of roles in the cell. Some are stored for
use as high-energy fuel (e.g. triacyl glycerides ;TAGs); others serve as essential
components of the cell membrane.
4. Nucleic acids:
The genetic material of the cell contains information for the cell growth, function and
propagation. The genetic material is made of DNA (deoxyribonucleic acid) and flow of
information takes place using RNA (ribonucleic acid).
Enzymes: Enzymes are functional proteins that are made up of specific sequence of
amino acids and act as biocatalysts in biochemical reactions. A Substrate (raw material)
is transformed into a finished product by the action of enzyme. Enzymes remain
unchanged during the reaction. A + B Enzyme P
Nutrients:
Nutrients are substances needed for growth, metabolism, and for other body functions.
i. Macronutrients:
Macronutrients are dietary requirement of living beings in bulk (large quantities) and
their major purpose is to provide energy. E.g. In humans dietary carbohydrtae, protein
and fat are macronutrients.
ii. Micronutrients:
Micronutrients are dietary requirements of living beings in small quantities and their
major function is to participate in physiological functions. E.g. In humans vitamins and
minerals are micronutrients.
Metabolism:
A cell cannot maintain its health unless it is continually forming and breaking down
proteins, carbohydrates, and lipids and using and storing energy. These active processes
of change are collectively called metabolism.
Thermodynamics of biological system:
According to the first law of thermodynamics, in any closed system, energy can neither
be created nor destroyed but is interconvertible Living beings are biosystems.
Biosystems build and break down biomolecules. In Biochemical reactions energy is
conserved as biomolecules or transformed into other forms such as ATP (adenosine
triphosphate) called the energy currency of the cell.
Biochemistry: A Brief History
1. Initially it was thought that only living beings could produce the molecules of life.
Then, in 1828, Friedrich Wohler published a paper on the synthesis of urea,
proving that organic compounds can be created artificially.
2. In 1833 the first enzyme, diastase (today called amylase) was discovered by Anselme
Payen.
3. 1865 Gregor Mendel proposed his theory of genetics (laws of inheritence of characters)
4. In 1869 Fredrick meischer discovers DNA in cell nuclei.
5. Eduard Buchner contributed the first demonstration of a complex biochemical
process outside of a cell in 1896: alcoholic fermentation in cell extracts of
yeast.
5. Although the term “biochemistry” seems to have been first used in
1882, it is generally accepted that the formal coinage of biochemistry
occurred in 1903 by Carl Neuberg, a German chemist.
6. 1914 Fritz Lipmann elucidates the role of ATP in energy metabolism.
7. 1926 James Sumner obtains crystalline jack bean urease and demostrates that
it is a protein.
8. 1926 Thomas Hunt Morgan writes The Theory of the Gene.
9. 1937 Hans Krebs discovers the citric acid cycle (TCA cycle).
10. 1941 George Beadle & Edward Tatum propose the one-gene, one-enzyme
hypothesis.
11. 1944 Oswald Avery, Colin MacLeod, and Maclyn McCarthy use chemical
methods to establish that DNA is the genetic material.
12. 1953 James Watson and Frances Crick put forth the double helix model of
DNA.
13. 1953 Fredrick Sanger determines the first amino acid sequence of a
protien(insulin).
Suggested readings
Harper's Illustrated Biochemistry, 28e
Robert K. Murray, David A Bender, Kathleen M. Botham, Peter J. Kennelly, Victor W. Rodwell, P. Anthony Weil
Copyright © 2009 by The McGraw-Hill Companies, Inc
Available in the University Library
Marks’ Basic Medical Biochemistry: A Clinical Approach
Lippincott Wiliams & Wilkins