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Title: Biochemistry - An Overview


1
Biochemistry ? An Overview
R.C.Gupta Professor and Head Dept. of
Biochemistry National Institute of Medical
Sciences Jaipur, India
2
  • Introduction
  • Living organisms are made up of chemical elements
    organized into bio-molecules
  • The important bio-molecules include nucleic
    acids, proteins, carbohydrates, lipids etc
  • They are made up mainly of carbon, hydrogen,
    oxygen and nitrogen with small amounts of some
    other elements

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  • 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

4
  • 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

5
  • With the help of enzymes, the cell oxidises
    the bio-molecules to extract energy
  • It can convert the raw materials into complex
    bio-molecules and supra- molecular assemblies

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6
  • Chemical events occurring in the cell
    maintain it in a dynamic steady state, even
    in a continually changing environment
  • And finally, the cell has the remarkable
    ability to reproduce itself

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  • Unicellular organisms, e.g. bacteria, are
    made up of a single cell having a simple
    architecture
  • Multicellular organisms have a highly
    organized cellular architecture
  • An adult human being has nearly 1014 cells
  • These cells are of different types having
    different shapes, sizes and functions

9
  • 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
    intercellular communication and co-
    ordination

10
  • A simple event like removing our hand on
    touching a hot object involves a series of
    reactions
  • These reactions occur in different types of
    cells involving a number of ions and
    molecules
  • Biochemistry seeks to explain the complex
    biological phenomena at the molecular
    level

11
  • 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

12
  • The information molecules, deoxyribo- nucleic
    acid (DNA) and ribonucleic acid (RNA), are
    similar
  • They made up of the same nucleotides
  • The genetic code is the same

13
  • 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

14
  • 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

15
  • The scope of biochemistry is very wide
  • It covers plants, animals, microbes, industry
    etc
  • We will be concerned here mainly with human
    (medical) biochemistry

16
  • Our study of human biochemistry will cover
  • Chemistry of amino acids and proteins
  • Enzymes
  • Chemistry of carbohydrates and lipids
  • Metabolism of carbohydrates, lipids, amino
    acids and proteins
  • Bio-energetics oxidative phosphorylation
  • Molecular biology

17
  • (Contd)
  • Vitamins and minerals
  • Hormones
  • Nutrition and dietetics
  • Maintenance of pH, water electrolyte
    balance
  • Cancer
  • Immunochemistry
  • Xenobiotics

18
  • Chemistry of amino acids and proteins
  • Amino acids are the building blocks for the
    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

19
  • Enzymes
  • Enzymes are the universal catalysts of the
    living world
  • No chemical reaction in living organisms can
    occur at a significant rate without enzymes
  • With a few exceptions, all enzymes are
    proteins having unique three- dimensional
    structures suited to their catalytic functions

20
  • Enzymes also play a crucial role in metabolic
    regulation
  • Rates of reactions in a metabolic pathway are
    usually regulated by altering the concentration
    or catalytic activity of one or a few key
    enzyme(s) in the pathway

21
  • 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 are used as drugs as well

22
  • Chemistry of carbohydrates and lipids
  • These are bio-molecules used mainly as
    sources of energy
  • Carbohydrates constitute the largest
    component of our daily diet

23
  • Lipids constitute the major storage form of
    energy
  • Some carbohydrates and lipids perform
    structural roles as well

24
Metabolism of carbohydrates, lipids, amino
acids and proteins
  • The chemical reactions these compounds undergo in
    the body constitute metabolism
  • The process begins with the digestion of dietary
    carbohydrates, lipids and proteins
  • This is followed by absorption of the products
    of digestion

25
  • The metabolic processes include
  • Anabolism i.e. synthesis of large molecules
    from small precursors
  • Catabolism i.e. breakdown of large molecules
  • Anabolism and catabolism occur by a series of
    reactions which constitute a metabolic pathway

26
  • While studying metabolic pathways, we will be
    interested in their
  • Tissue distribution
  • Intracellular location
  • Reactions
  • Energetics
  • Regulation
  • Importance

27
  • Some disorders can occur due to a block in
    some reaction of the pathway owing to a
    mutated, dysfunctional enzyme
  • We will also have a look at such metabolic
    disorders

28
  • Bio-energetics and oxidative phosphorylation
  • Energy is released during catabolism of
    carbohydrates, lipids and amino acids
  • This energy is utilized in anabolic pathways
    and for muscle contraction, active transport
    etc
  • Adenosine triphosphate (ATP) is the universal
    carrier of energy

29
  • ATP is
  • Formed during exergonic (energy- yielding)
    reactions
  • Utilized in endergonic (energy- consuming)
    activities
  • Oxidative phosphorylation is the process by
    which energy released during cata- bolism of
    carbohydrates, lipids and amino acids is
    captured in the form of ATP

30
  • Molecular biology
  • Molecular biology comprises the chemistry and
    metabolism of nucleic acids and their building
    blocks
  • Nucleic acids are DNA and RNA
  • Their building blocks are nucleotides

31
  • DNA and RNA are information molecules
  • Genetic information is present in DNA in the
    form of genes
  • A gene possesses coded information about the
    amino acid sequence of a protein

32
  • An RNA transcript of the gene carries the
    information from the DNA to the ribosomes
  • Using this information, protein is
    synthesized on the ribosome
  • During cell division, DNA of the cell is
    exactly replicated
  • The daughter cells acquire the genetic
    information present in the parent cell

33
  • Our study of molecular biology will cover
    processes like
  • Replication (synthesis of DNA)
  • Transcription (synthesis of RNA)
  • Translation (synthesis of proteins)
  • A recent and revolutionary development in
    molecular biology is the advent of recombinant
    DNA technology

34
  • A revolutionary development in molecular
    biology is the advent of recombinant DNA
    technology
  • This technology is finding wide-ranging
    applications in all life sciences
  • We will study the tools and techniques of
    this technology and its applications in
    medical science

35
  • Vitamins
  • Vitamins are a group of chemically diverse
    organic compounds required in minute
    quantities but essential for life
  • Some vitamins act as coenzymes, essential for
    the activity of a number of enzymes
  • Others are required for growth,
    differentiation, vision etc

36
  • Deficient intake of most, and excessive
    intake of some, vitamins produces specific
    diseases
  • Our study of vitamins will cover their
  • Chemistry
  • Functions
  • Requirements
  • Dietary sources
  • Diseases resulting from their deficient or
    excessive intake

37
  • Minerals
  • Several minerals are essential for human beings
  • Some are required in relatively large quantities
    (macronutrients)
  • Others are required in minute quantities
    (micronutrients)

38
  • Minerals perform a variety of functions e.g.
  • Formation of bones (Ca and P)
  • Nerve conduction (Na and K)
  • Formation of haemoglobin (Fe)
  • Cofactors for enzymes (Cu, Zn, Se etc)
  • Their deficiency or excess can cause disease

39
  • Hormones
  • Hormones are mobile molecules that carry
    signals from one organ, tissue or cell to
    another
  • They help the organism to respond in a
    coordinated manner to any change in internal
    or external environment
  • Small changes in the concentrations of
    hormones produce profound biochemical and
    physiological effects

40
  • Under- or over-production of hormones
    produces serious disorders
  • Diagnosis of these disorders usually requires
    measurement of hormone concentrations in blood

41
  • Maintenance of pH, water and electrolyte
    balance
  • Water, in intra- and extra-cellular
    compartment, constitutes nearly two-thirds of
    the body weight in an adult man
  • Water is the universal solvent of the living
    world, and is the medium in which all
    biochemical reactions occur

42
  • Small changes in the water content,
    distribution 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

43
  • Nutrition and dietetics
  • 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

44
  • Diseases resulting from under-nutrition
    afflict large sections of population in poor
    societies while over-nutrition is the bane
    of the rich
  • Ignorance contributes significantly to
    both
  • A sound knowledge of principles of nutrition
    and dietetics is essential to prevent and
    treat the nutritional disorders

45
  • Cancer
  • Cancer (malignancy) has emerged as a leading
    cause of death worldwide
  • A number of physical, chemical and biological
    agents are known to cause cancer
  • But the molecular mechanisms that transform a
    healthy cell into a cancer cell have eluded us
    for a long time

46
  • Advances in molecular biology are now
    revealing the complex interplay of anti-
    oncogenes, proto-oncogenes and onco- genes
  • These interactions can result in trans-
    formation of a normal cell into a cancer cell
  • We will look at the role of these genes in
    malignant transformation

47
  • Immunochemistry
  • We are exposed to a bewildering range of
    foreign antigens that can cause disease
  • We also have a highly competent immune system
    to protect us against these antigens
  • The immune system comprises innate immunity
    and adaptive immunity

48
  • A number of molecules are involved in the
    recognition and inactivation of foreign
    antigens
  • We will study the molecules of immune
    recognition and the mechanisms by which the
    foreign antigens are dealt with

49
  • Xenobiotics
  • Apart from antigens, we are exposed to a vast
    variety of foreign chemicals (xenobiotics) that
    can cause toxicity
  • We will look at the mechanisms by which the
    xenobiotics are detoxified and excreted

50
  • Our study of human biochemistry will, thus,
    provide us insights into the molecular
    basis of complex biological phenomena
  • Biochemistry is described as the chemical
    language of life

51
  • This language helps us
  • In understanding the normal functioning of
    the body at the molecular level
  • In unraveling the molecular basis of diseases
  • In diagnosis of diseases by laboratory
    investigations
  • In treatment by providing enzymes, enzyme
    inhibitors and gene therapy

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