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CHAPTER – I
INTRODUCTIION AND IMPORTANCE OF BIOCHEMISTRY
Biochemistry, as the name implies, is the chemistry of living organisms. It
bridges the gap between the conventional chemistry and biology.
organisms have certain extraordinary properties.
Living
They can grow, respond to
stimuli and replicate themselves with high fidelity.
All these activities are
ultimately interpretable in chemical terms. The lifeless organic molecules with
appropriate complexity and properties make a living thing. The basic phenomena
of biochemistry are to understand how the collections of inanimate molecules that
constitute living organisms interact with each other to maintain life. The basic life
processes or chemistry remains broadly the same whether it is a unicellular
microorganism or the higher organisms such as human or plants. Life is nothing
but thousands of ordered chemical reactions. In other words, chemistry is the
logic of all biological phenomena.
Biochemistry deals with the chemical nature and chemical behaviour of the
living organisms. The word biochemistry is derived from bios – meaning life. The
metabolic processes are studied in this branch.
Today, there are three main types of biochemistry. Plant biochemistry
involves the study of the biochemistry of autotrophic organisms such as
photosynthesis and other plant specific biochemical processes. General
biochemistry
encompasses
both
plant
and
animal
biochemistry.
Human/medical/medicinal biochemistry focuses on the biochemistry of humans
and medical illnesses.
There is tremendous importance of biochemistry in agriculture. The
chemical processes leading to metabolism of protein, carbohydrate, oils, vitamins
and minerals, apart from secondary products from plant such as gum, mucilage,
oleoresins, terpenes, essential oils, phenolics, alkaloids etc. are more important for
farmers and end users for quality of crop and end products of the plants. The
genetic engineering and biotechnology involve a great deal of biochemistry for crop
improvement.
1.1 History of biochemistry
Only during 17th and 18th centuries, important foundations were laid in
many fields of biology.
The 19th century observed the development of very
crucial concepts, which include the cell theory by Schleiden and Schwann,
Mendel’s study of inheritance and Darwin’s theory of evolution. The real push to
biochemistry was given in 1828 when total synthesis of urea from lead cyanate
and ammonia was successfully achieved by Wohler who thus initiated the
synthesis of organic compound from inorganic compound. Louis Pasteur, during
1857, did a great deal of work on fermentations and pointed out categorically the
central importance of enzymes in this process. The breakthrough in enzyme
research and hence, biochemistry was made in 1897 by Edward Buckner when
he extracted enzyme from yeast cells in crude form which could ferment a sugar
molecule into alcohol. Neuberg introduced the term biochemistry in 1903.
The early part of 20th century witnessed a sudden outburst of knowledge in
chemical analysis, separation methods, electronic instrumentation for biological
studies (X-ray diffraction, electron microscope, etc) which ultimately resulted in
understanding the structure and function of several key molecules involved in life
processes such as proteins, enzymes, DNA and RNA.
In 1926, James Sumner established the protein nature of enzyme. He
was responsible for the isolation and crystallization of urease, which provided a
breakthrough in studies of the properties of specific enzymes.
The first metabolic pathway elucidated was the glycolytic pathway during
the first half of the 20th century by Embden and Meyerhof. Otto Warburg, Cori
and Parnas also made very important contributions relating to glycolytic pathway.
Krebs established the citric acid and urea cycles during 1930-40.
In 1940,
Lipmann described the central role of ATP in biological systems.
The biochemistry of nucleic acids entered into a phase of exponential
growth after the establishment of the structure of DNA in 1953 by Watson and
Crick followed by the discovery of DNA polymerase by Kornberg in 1956. From
1960 onwards, biochemistry plunged into an interdisciplinary phase sharing much
in common with biology and molecular genetics.
Frederick Sanger’s contributions in the sequencing of protein in 1953 and
nucleic acid in 1977 were responsible for further developments in the field of
protein and nucleic acid research.
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The growth of biochemistry and molecular biology was phenomenal during
the past two decades. The development of recombinant DNA research by Snell
and coworkers during 1980 allowed for further growth and emergence of a new
field, the genetic engineering.
Thus there was progressive evolution of biology to biochemistry and then
to molecular biology, genetic engineering and biotechnology. The major
contributions made by some of the Scientists in the developments of biochemistry
are listed below in table 1.1.
Table 1.1
Scientists and their major contribution to biochemistry and
related fields.
1780-1789
Lavoisier
1828
Wohler
1837
Berzelius
1838
1854-1864
Schleiden and
Schwann
Louis Pasteur
1866
Mendel
1869
1877
1894
Miescher
Kuhne
Emil Fischer
1897
Buckner
1902
1903
1905
Emil Fischer
Neuberg
Harden and
Young
1912
1913
Neuberg
Michaelis and
Menten
Sumner
1926
1933
Embden
Meyerhof
Recognized that respiration is oxidation and first
measured oxygen consumption by human subject
Synthesized the first organic compound, urea
from inorganic components
Postulated the catalytic nature of fermentation. He
also identified lactic acid as a product of muscle
activity.
Enunciated the cell theory
Proved
that fermentation
is caused
by
microorganisms
Reported the principles of segregation and
independent assortment of genes
Discovered DNA
Proposed the term ‘Enzyme’
Demonstrated the specificity of enzymes and the
lock and key relationship between enzyme and
substrate
Discovered alcoholic fermentation in cell-free yeast
extract
Demonstrated that proteins are polypeptides
First used the term ‘biochemistry’
Showed the requirement of phosphate in alcoholic
fermentation and identified first coenzyme,
cozymase, later shown to be NAD
Proposed chemical pathway for fermentation
Developed kinetic theory of enzyme action
First crystallized an enzyme, urease and proved it
to be a protein
Demonstrated crucial intermediates in the chemical
and pathway of glycolysis and fermentation
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1937
1940
1940
1944
1948
1950
1950-1953
1953
1953
1954
Parnas
Krebs
Lipmann
Beadle and
Tatum
Avery, MacLeod
and McCarty
Calvin and
Benson
Pauling and
Corey
Chargaff
Sanger and
Thompson
Watson
and
Crick
Arnon and
Colleagues
Discovered citric acid cycle
Role of ATP in biological systems
Deduced one gene-one enzyme relationship
Demonstrated that bacterial transformation was
caused by DNA
Discovered that phosphoglyceric acid is an early
intermediate in photosynthetic CO2 fixation
Proposed the -helix structure for keratins
Discovered the base composition of DNA
Determined the complete amino acid sequence of
insulin
Proposed the double-helical model for DNA
structure
Discovered photosynthetic phosphorylation
1956
Kornberg
Discovered DNA polymerase
1958
Meselson and
Stahl
Hamilton and
Daniel Nathans
Jacob & Monod
Confirmed the Watson-Crick
conservative replication of DNA
Restriction endonucleases
1961
Nirenberg and
Matthaei
1961-1965
Nirenberg
Khorana and
Ochoa
Reported that polyuridylic acid codes for
phenylalanine and this opened the way to
identification of genetic code
Identified the genetic code words for amino acids
1969
Arber
Restriction endonucleases
1977
Sanger
Determination of DNA sequence
1980
Snell
Development of recombinant DNA research leading
to genetic engineering
1984
Kary Mullis
Polymerase chain reaction
1997
Wilmut
1999
Ingo potrykus
Viable offspring derived from fetal and adult
mammalian cells.
Golden rice rich in -carotene
2006
Andrew Z. Fire Nobel Prize for discovering the role of RNA
and Craig C. interference (RNAi), in the silencing of gene
Mello
expression
1960
1961
model
of
semi
Proposed the operon hypothesis and postulated the
function of messenger RNA
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In 20th century, due to development of analytical instruments, rapid
progress in biochemistry was made.
The use of Radio Isotope labelling studies / Mass Spectroscopy /
Electrophoresis / Spectrophotometry / NMR and genetic engineering methods
speeded up the research on biochemistry.
We are inan exciting time in Plant Biochemistry. The next century is
anticipated to be "The Century of Biology" with advances in biotechnology
expected to lead economic development. Not only will we be able use advances
in Plant Biochemistry to produce better, more nutritious foods which will improve
human health more than any other medical advance, but we are on the verge of
using plants as sophisticated chemical factories to produce all manner of
materials useful to medicine and industry. We are beginning to understand the
structure and function of an increasing number of enzymes and other proteins
and this is spawning the development of rational design of enzyme function and
other methods of protein engineering.
A growing number of prokaryote and lower eukaryote genomes have
already been completely sequenced and a near complete sequence of the
Arabidopsis genome was published in December, 2000. The entire human
genome DNA completely sequenced and published in March 2003.
We are moving from structural to functional genomics with this latter field
being particular relevant to biochemistry. "Information about the function of a
protein is contained not in its primary sequence but in its structure, so the
classical 'protein folding problem' - how proteins reach their native, folded state
from the unfolded, newly synthesized polypeptide - now takes on new
significance.
Double bond is introduced into fatty acids in plants by a soluble stromal
ACP desaturase. This desaturase normally has high specificity for 18:0-ACP and
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inserts a cis
A small number
of plant species in several families posses other acyl-ACP desaturases.
Coriandrum sativum
4-palmitoyl
(16:0)-ACP desaturase
that inserts a double bond at carbon 4 of 16:0. Thunbergia alata (black-eyed
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6-16:0-ACP
9-myristoyl
desaturase and Pelargonium xhortorum
(14:0)-ACP desaturase.
By comparing the protein sequences of these 3 soluble desaturases and
R. communis
9-18:0-ACP
desaturase and analyzing 3-dimensional structural
information from the crystal structure of the R. communis
9-18:0-ACP
desaturase, Cahoon et al. were able to decipher the molecular basis for chainlength recognition and positional placement of double bonds into fatty acids.
They showed that the regio-specificities could be modified by replacement of
specific amino acid residues and that acyl-ACP activities can be rationally
redesigned.
9-18:0-ACP
desaturase contains a catalytic diiron cluster (and all the
other above-mentioned soluble desaturase contain the conserved iron-binding
domains) that represents a fixed point for double bond introduction. Adjacent to
these iron atoms is a deep, narrow channel that Cahoon et al. predicted was the
binding pocket for the 18:0 portion of the substrate. The channel forces the 18:0
to bend at carbons 9-10 that corresponds to the cis configuration of the 18:1
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product. Thus the architecture of the substrate-binding channel appeared to
determine substrate acyl-chain length, position and stereochemistry of the
introduced double bond.
9-18:0-ACP
desaturase
substrate channel with the 18:0 substrate docked is shown in Fig. 3 of Cahoon et
al. They predicted that substitution of alanine-188 for the smaller glycine (G188)
and tyrosine-
6-16:0-ACP
desaturase would
extend the cavity at the bottom of the desaturase active site enough to permit 2
more carbon atoms at the methyl end of 18:0-ACP. They in fact found that
mutant A188G/Y189F is able to desaturate 18:0-ACP at a similar rate as with
16:0-ACP.
1. It is useful in the treatment of animals and man.
2. It is helpful to fix the need of food and nutrients in animals, so that the
malnutrition in population may be avoided.
3. It is helpful in developing the strategy for higher production of crops.
4. Used in science of pharmacology and drugs.
5. Preservation of fruits and vegetables can be prolonged with the help of
biochemistry knowledge.
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6. Its study is helpful in understanding chemical changes during storage and
processing of food material.
7. The plant breeding and genetics branch of agriculture is based on biochemical
mechanism of genes.
8. Nutrition and care of cattle, cows and buffaloes
9. Metabolisms of different food nutrients are studied with the help of biochemistry.
10. The problems of biology and medical science can be solved.
11. Nutritional deficiency diseases, malnutrition, planning of balanced diet and
energy requirement of human being involve the knowledge of biochemistry.
12. Enzymatic reaction of metabolic pathway and its regulation for higher
productivity i.e. photosynthesis, reduction of respiration rate.
13.
To improve the quality of starch through modification of
regulatory
enzyme
14. To assess the nutritional quality of starch, protein and carbohydrates etc of
products.
15. To enhance the N fixation in plants
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Biochemistry Introduction
Overview and Introduction to Biochemistry
By Anne Marie Helmenstine, Ph.D.
Biochemistry is the study of the molecules of life, such as DNA.
Ben Mills
See More About
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biochemistry
biochemist
organic chemistry
chemistry disciplines
Biochemistry is the science in which chemistry is applied to the study of living organisms and
the atoms and molecules which comprise living organisms. Take a closer look at what
biochemistry is and why the science is important.
What Is Biochemistry?
Biochemistry is the study of the chemistry of living things. This includes organic molecules and
their chemical reactions. Most people consider biochemistry to be synonymous with molecular
biology.
What Types of Molecules Do Biochemists Study?
The principal types of biological molecules, or biomolecules are:
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carbohydrates
lipids
proteins
nucleic acids
Many of these molecules are complex molecules called polymers, which are made up of
monomer subunits. Biochemical molecules are based on carbon.
What Is Biochemistry Used For?
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Biochemistry is used to learn about the biological processes which take place in cells
and organisms.
Biochemistry may be used to study the properties of biological molecules, for a variety
of purposes. For example, a biochemist may study the characteristics of the keratin in
hair so that a shampoo may be developed that enhances curliness or softness.
Biochemists find uses for biomolecules. For example, a biochemist may use a certain
lipid as a food additive.
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Alternatively, a biochemist might find a substitute for a usual biomolecule. For
example, biochemists help to develop artificial sweeteners.
Biochemists can help cells to produce new products. Gene therapy is within the realm
of biochemistry. The development of biological machinery falls within the realm of
biochemistry.
What Does a Biochemist Do?
Many biochemists work in chemistry labs. Some biochemists may focus on modeling, which
would lead them to work with computers. Some biochemists work in the field, studying a
biochemical system in an organism. Biochemists typically are associated with other scientists
and engineers. Some biochemists are associated with universities and they may teach in
addition to conducting research. Usually their research allows them to have a normal work
schedule, based in one location, with a good salary and benefits.
What Disciplines Are Related to Biochemistry?
Biochemistry is closely related to other biological sciences that deal with molecules. There is
considerable overlap between these disciplines:
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Molecular Genetics
Pharmacology
Molecular Biology
Chemical Biology
When you major in agricultural biochemistry you explore the unknown, the unseen, and the
undiscovered wonders of the natural world.
Your coursework will provide a foundation in chemistry, physics, mathematics, and biology, as those fields
relate to agricultural and biological sciences. Biochemists study plant, animal, and microbial metabolism as
well as the structure and biological function of nucleic acids, proteins, carbohydrates, and lipids by using
modern techniques such as x-ray crystallography and NMR spectroscopy.
Biochemistry is fundamental to modern biotechnology. As an agricultural biochemistry student, you stand on
the frontier of scientific discoveries that change our understanding of the world: new approaches to diabetes,
nutrition for athletes, developments in genetically engineered, insect-resistant plants, and methods for
detecting vitamin and mineral deficiencies.
Most agricultural biochemistry graduates continue their training to pursue careers in agricultural and
biological sciences and in human and veterinary medicine.
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