1. Living organisms are composed of biomolecules like nucleic acids, proteins, carbohydrates and lipids made from carbon, hydrogen, oxygen and nitrogen. 2. Within cells, these biomolecules and inorganic elements confer the property of life and allow the cell to obtain materials, produce enzymes, and undergo chemical reactions to sustain itself. 3. Biochemistry studies the biomolecules, elements, and chemical reactions within living things to understand functions at the molecular level, from single-celled to multicellular organisms.

1. Biochemistry ‒ An Overview
R. C. Gupta
M.D. (Biochemistry)
Jaipur, India

2. Living organisms are made up of chemical
elements organized into bio-molecules
Important bio-molecules include nucleic
acids, proteins, carbohydrates, lipids etc
These are made up of C, H, O and N with
small amounts of some other elements

3. Several inorganic elements are also
present in living organisms
By themselves, the bio-molecules and
the inorganic elements are non-living
But when they come together in a cell,
they confer the property of ‘life’ to the cell

5. Cell is the structural and functional unit of
all living organisms
It obtains raw materials required for
sustaining itself from its environment
From raw materials, it produces the
biological catalysts (enzymes) that
catalyse biochemical reactions in the cell

6. With the help of enzymes, the cell oxidizes
the bio-molecules to extract energy
It can convert raw materials into complex
molecules and supra-molecular assemblies

7. Chemical events occurring in the cell
keep it in a dynamic steady state, even in
a continually changing environment
And finally, the cell has the remarkable
ability to reproduce itself

8. Biochemistry encompasses
the study of:
Bio-molecules and elements
essential for life
The chemical reactions they
undergo to subserve various
functions of the organism

9. Unicellular organisms, e.g. bacteria, are
made up of a single cell having a simple
architecture
Multicellular organisms have a highly
organized cellular architecture

10. Multicellular
Unicellular

11. An adult human being has nearly 1014
cells
These cells are of different types having
different shapes, sizes and functions

12. The cells are organized into tissues and
tissues into organs
This differentiation gives us the advantage
of division of labour
But it also poses the problem of cell-cell
communication and co-ordination

13. A simple event like removing our hand
on touching a hot object involves a
series of reactions

14. These reactions occur in different types
of cells involving a number of ions and
molecules
Biochemistry seeks to explain such
complex biological phenomena at the
molecular level

15. The structural organization of cells
differs from organism to organism
But there is a remarkable degree of
unity in this diversity
The bio-molecules present in different
types of cells are similar

16. The information molecules, ribonucleic acid
and deoxyribonucleic acid, are similar
They are made up of the same nucleotides
The genetic code is the same

17. The proteins are made up of the same
twenty amino acids
The biological catalysts are similar
The currency of energy is the same
The metabolic pathways are similar

18. Due to this similarity, information
obtained in one organism can be
extrapolated to others
Much of the information about human
biochemistry has been obtained from
experiments in simple organisms like
bacteria

19. The scope of biochemistry is very wide
It covers plants, animals, microbes,
industry etc
Human biochemistry concerns the bio-
chemistry of human health and disease

20. Study of human biochemistry covers:
• Chemistry of amino acids and proteins
• Enzymes
• Chemistry of carbohydrates and lipids
• Metabolism of carbohydrates, lipids,
amino acids and proteins
• Bio-energetics and oxidative
phosphorylation
• Molecular biology
Continued …

21. • Vitamins and minerals
• Hormones
• Nutrition and dietetics
• Maintenance of pH, water and
electrolyte balance
• Cancer
• Immunochemistry
• Xenobiotics

22. Amino acids are the building blocks for
synthesis of proteins
Proteins form the structural framework
of tissues and perform a variety of
other functions in the form of enzymes,
hormones, receptors, antibodies etc
Chemistry of amino acids and proteins

23. Enzymes are the universal catalysts of
the living world
No reaction in living organisms can occur
at a significant rate without enzymes
Enzymes

24. With a few exceptions, all enzymes are
proteins
They have unique three-dimensional
structures suited to their catalytic
functions

25. Enzymes also play a crucial role in
metabolic regulation
One (or a few) key enzyme(s) regulate
a metabolic pathway
Rates of reactions are regulated by
altering the concentration or catalytic
activity of the key enzyme(s)

26. Many diseases can be diagnosed by
measuring the levels of some enzymes
in biological fluids e.g. plasma
Many inhibitors of enzymes are used as
drugs
Some enzymes themselves are used as
drugs

27. Carbohydrates and lipids are used
mainly as sources of energy
Carbohydrates constitute the largest
component of our daily diet
Chemistry of carbohydrates and lipids

28. Lipids constitute the major storage form
of energy
Some carbohydrates and lipids perform
structural roles as well

29. The chemical reactions the biomolecules
undergo in the body constitute metabolism
The process begins with the digestion of
complex biomolecules
This is followed by absorption of the
products of digestion
Metabolism of carbohydrates, lipids,
amino acids and proteins

30. The metabolic
processes include:
Anabolism i.e. synthesis of large
molecules from small precursors
Catabolism i.e. breakdown of
large molecules

31. Anabolism and catabolism occur by a
series of reactions
Each reaction series constitutes a
metabolic pathway
There are a number of pathways for
metabolism of carbohydrates, lipids and
amino acids

32. While studying metabolic pathways,
we should look at their:
• Tissue distribution
• Intracellular location
• Reactions
• Energetics
• Regulation
• Importance
• Disorders

33. Metabolic disorders occur due to a
block in some reaction of the pathway
The block occurs owing to a mutated,
dysfunctional enzyme

34. Energy is released during oxidation of
carbohydrates, lipids and amino acids
It is captured by oxidative phosphorylation
It is utilized in anabolic pathways and for
muscle contraction, active transport etc
Bio-energetics and oxidative
phosphorylation

35. Adenosine triphosphate (ATP) is the
universal currency of energy
ATP is formed during energy-yielding
(exergonic) reactions
ATP is utilized in energy-consuming
(endergonic) activities

36. Molecular biology is the study of nucleic
acids and their building blocks
Nucleic acids are deoxyribonucleic acid
(DNA) and ribonucleic acid (RNA)
Their building blocks are nucleotides
Molecular biology

37. DNA and RNA are known as information
molecules
Genetic information is present in DNA in
the form of genes
A gene possesses coded information
about amino acid sequence of a protein

38. An RNA transcript of gene carries
information from DNA to the ribosomes
Using this information, the protein is
synthesized on the ribosome

39. During cell division, DNA of the cell is
exactly replicated
The daughter cells acquire the genetic
information present in the parent cell

40. Study of molecular biology
includes processes like:
Replication (synthesis of DNA)
Transcription (synthesis of RNA)
Translation (synthesis of proteins)
Recombinant DNA technology

41. Recombinant DNA technology has led to
a revolution in molecular biology
Its study comprises the study of its tools,
techniques and applications
Recombinant DNA technology is finding
applications in all life sciences

42. Vitamins are a group of chemically
diverse organic compounds required in
minute quantities but essential for life
Many vitamins act as coenzymes,
essential for the activity of a number of
enzymes
Vitamins

43. Some vitamins are required for growth,
differentiation, vision etc
Deficient intake of most, and excessive
intake of some, vitamins produces
specific diseases

44. Study of vitamins covers their:
• Chemistry
• Functions
• Requirements
• Dietary sources
• Diseases resulting from deficient or
excessive intake

45. A number of minerals are essential for
human beings
Some are required in relatively large
quantities (macronutrients)
Others are required in minute quantities
(micronutrients)
Minerals

46. Minerals are required for:
• Formation of bones (Ca and P)
• Nerve conduction (Na and K)
• Formation of haemoglobin (Fe)
• Activity of enzymes (Cu, Zn, Se etc)

47. Study of minerals covers their:
• Functions
• Requirements
• Dietary sources
• Diseases resulting from deficient or
excessive intake

48. Hormones are mobile signal molecules
They carry signals from one organ,
tissue or cell to another
They are required for intercellular
communication and co-ordination
Hormones

49. Hormones help the organism to respond
to any change in internal or external
environment in a coordinated manner
Small changes in the concentrations of
hormones produce profound physio-
logical and biochemical effects

50. Under- or over-production of hormones
produces serious disorders
Diagnosis of these disorders usually
requires biochemical measurement of
hormone concentrations in blood

51. Water constitutes nearly two-thirds of
the body weight in an adult man
Water is the universal solvent of the
living world
It is the medium in which all biochemical
reactions occur
Maintenance of pH, water and
electrolyte balance

52. Small changes in water content, distri-
bution of electrolytes and pH of body
fluids can derange normal functioning
Such changes can occur in a variety of
diseases
Correction of the imbalance requires a
sound understanding of normal regulatory
mechanisms

53. We obtain all the nutrients we require,
viz. carbohydrates, lipids, proteins,
vitamins and minerals, from food
Malnutrition (under- and over-nutrition)
is common all over the world
Nutrition and dietetics

54. Diseases resulting from under-nutrition
afflict large sections of poor
Over-nutrition is the bane of the rich
Ignorance contributes significantly to
both

55. Correction of under-nutrition and over-
nutrition requires a sound knowledge of
principles of nutrition and dietetics
Dietary advice is required in some non-
nutritional diseases also

56. Cancer (malignancy) has emerged as a
leading cause of death worldwide
A number of physical, chemical and bio-
logical agents are known to cause cancer
Cancer

57. Molecular mechanisms that transform a
healthy cell into a cancer cell have eluded
us for a long time
Advances in molecular biology are now
revealing the interplay of anti-oncogenes,
proto-oncogenes and onco-genes
This complex interplay can transform a
normal cell into a cancer cell

58. We are exposed to a vast range of foreign
antigens that can cause disease
To protect us against these antigens, we
have a very competent immune system
The immune system comprises innate
immunity and adaptive immunity
Immunochemistry

59. A number of molecules are involved in
recognition and inactivation of antigens
Immunochemistry is the study of mole-
cules of immune recognition and the
mechanisms by which the foreign
antigens are dealt with

60. Apart from antigens, we are exposed to a
variety of foreign chemicals, known as
xenobiotics, that can cause toxicity
Through biochemistry, we understand the
mechanisms by which the xenobiotics are
detoxified and excreted
Xenobiotics

61. Study of human biochemistry, thus,
gives us insights into the molecular
basis of complex biological phenomena
Biochemistry is, therefore, described as
the chemical language of life

62. This chemical language helps us:
• In understanding the normal functioning
of the body at molecular level
• In unraveling the molecular basis of
diseases
• In diagnosing diseases by laboratory
investigations
• In treatment by providing enzymes,
enzyme inhibitors and gene therapy