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

E M B - R C G
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

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

E M B - R C G
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

E M B - R C G
7
EMB-RCG
8

• 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

EMB-RCG
52
Thank you