LECTURE 1.

1
INTRODUCTION TO
BIOCHEMISTRY
Dr. Ali Amar (Ph.D.)
Assistant Professor (MLT)
PKLI Institute of Nursing & Allied Health Sciences
Pakistan Kidney and Liver Institute & Research Center
(PKLI&RC), Lahore
 LEARNING OBJECTIVES
By the end of this lecture, students should be able to:
1. Define biochemistry and its importance in health sciences.
2. Understand the chemical basis of life.
3. Identify and classify major biomolecules.
4. Explain the basic role of bioenergetics in biochemical
processes.
5. Recognize the applications of biochemistry in medicine
and allied health sciences.
 DEFINITION OF BIOCHEMISTRY
• Biochemistry is the study of chemical basis of life. It
combines biology and chemistry to understand life at the
molecular level.
• It is the science concerned with the molecules present in
living organisms, individual chemical reactions and their
enzyme catalysts, and the expression and regulation of
each metabolic process.
• Biochemistry has become the basic language of all biologic
sciences.
 EVOLUTION OF BIOCHEMISTRY
Important milestones in evolution of Biochemistry
• Pasteur's work on fermentation 1857
• The term "biochemistry" proposed by Carl
Neuberg 1903
• Discovery of Insulin 1921
• Discovery of Kreb’s cycle 1937
• Fred Sanger’s development of DNA
sequencing method 1977.
• Complete understanding of photosynthesis
• Discovery of siRNA/miRNA 1998 and 2024
• Discovery of CRISPR-Cas9 genome editing
2020
 CHEMICAL BASIS OF LIFE: ATOMS,
ELEMENTS, AND MOLECULES
• Atoms (C, H, O, N, P, S) as the building blocks of life.
• Chemical bonds (covalent, ionic, hydrogen bonds).
• Water as the universal solvent in biological systems.
• pH and buffers in maintaining homeostasis.
 CHEMICAL BASIS OF LIFE: ORGANIC
VS. INORGANIC COMPOUNDS
• Organic compounds: Contain carbon (e.g., carbohydrates,
proteins, lipids, nucleic acids).
• The biomolecules that are present in living organisms are
carbon-based compounds.
• Carbon is the third most abundant element in living organisms
(relative abundance H > O > C > N > P > S).
• Inorganic compounds: Do not contain carbon (e.g., water, salts,
minerals).
• The most common ions are Ca+2, K+, Na+, Mg+2, and Cl-.
 BIOMOLECULES
• Biomolecules are organic molecules produced by and essential to living organisms,
playing vital roles in structure, function, and metabolism.
Four major classes:
Carbohydrates, Proteins, Lipids, Nucleic Acids.
Biopolymers are formed by condensation reactions in which water is removed from
the reacting monomer units.
Functions
• Structural: Biomolecules provide the building blocks for cell structures and tissues.
• Energy: Carbohydrates and lipids are primary energy sources.
• Information Storage: Nucleic acids store and transmit genetic information.
• Catalysis: Proteins, particularly enzymes, speed up biochemical reactions.
• Regulation: Hormones and other biomolecules regulate various physiological processes.
 CARBOHYDRATES
• Composition: Sugars and polymers of sugars.
• Structural/functional significance: Energy source (glucose), structural
(cellulose).
• Sub-classes:
• Monosaccharides (glucose, fructose)
• Disaccharides (sucrose, lactose)
• Polysaccharides (starch, glycogen)
• Associated pathophysiological conditions:
• Diabetes Mellitus (Type 1 & Type 2) – Impaired insulin function leading to
hyperglycemia.
• Glycogen Storage Diseases (e.g., Von Gierke’s disease, McArdle disease) –
Defects in glycogen metabolism.
• Galactosemia – Inability to metabolize galactose.
• Lactose Intolerance – Deficiency of lactase enzyme.
• Metabolic Syndrome – Insulin resistance and dysregulated glucose metabolism.
 PROTEINS
• Composition: Polymers of amino acids.
• Structural/functional significance: Enzymes, structural support (collagen),
transport (hemoglobin)
• Sub-classes: Different sub-classes based on
• Composition (simple, conjugated & derived),
• Structure (Fibrous & Globular)
• Function (Structural, Catalytic, Transport, Hormonal, Storage etc)
• Levels of protein structure: (primary, secondary, tertiary, quaternary)
• Associated pathophysiological conditions:
• Phenylketonuria (PKU) – Defect in phenylalanine hydroxylase.
• Sickle Cell Anemia – Abnormal hemoglobin (HbS) due to a point mutation.
• Cystic Fibrosis – Defective CFTR protein affecting chloride transport.
• Amyloidosis – Abnormal protein (amyloid) deposition in tissues.
• Albinism – Tyrosinase deficiency affecting melanin production.
 LIPIDS
• Composition: Hydrophobic molecules (fats, oils, waxes)
• Structural/functional significance: Energy storage, cell membrane
structure (phospholipids), signaling (steroids)
• Sub-classes: Triglycerides, phospholipids, steroids.
• Associated pathophysiological conditions:
• Atherosclerosis – Cholesterol and LDL deposition in arterial walls.
• Hyperlipidemia/Dyslipidemia – Elevated triglycerides and cholesterol.
• Familial Hypercholesterolemia – LDL receptor defect leading to high
cholesterol.
• Obesity – Excessive fat accumulation due to metabolic dysregulation.
• Fatty Liver Disease (NAFLD/NASH) – Abnormal lipid accumulation in
hepatocytes.
• Lipid Storage Diseases (e.g., Gaucher’s, Tay-Sachs, Niemann-Pick) –
Lysosomal enzyme deficiencies.
 NUCLEIC ACIDS
• Composition: Polymers of nucleotides (phosphate, sugar, nitrogenous
base).
• Structural/functional significance: Genetic information storage and
transmission (DNA → RNA → protein).
• Sub-classes: DNA and RNA.
• Associated pathophysiological conditions:
• Gout – Uric acid crystal deposition due to purine metabolism dysfunction.
• Lesch-Nyhan Syndrome – HGPRT enzyme deficiency affecting purine
metabolism.
• Cancer – Mutations in DNA leading to uncontrolled cell proliferation.
• Down Syndrome (Trisomy 21) – Chromosomal abnormality.
• Cystic Fibrosis, Sickle Cell Anemia (also involve DNA mutations).
• Xeroderma Pigmentosum – Defective DNA repair mechanisms.
 OTHER BIOMOLECULES
• Vitamins and coenzymes.
• Hormones (e.g., insulin, adrenaline).
• Minerals (e.g., Ca²⁺, Fe²⁺).
• Associated pathophysiological conditions:
• Scurvy – Vitamin C deficiency (impaired collagen synthesis).
• Rickets/Osteomalacia – Vitamin D deficiency (impaired calcium
absorption).
• Diabetes Mellitus (Insulin deficiency/resistance).
• Hypothyroidism/Hyperthyroidism (Thyroid hormone imbalance).
• Goiter/Hypothyroidism – Iodine deficiency.
• Hypokalemia/Hyperkalemia – Potassium imbalance (cardiac
arrhythmias).
 BIOENERGETICS
• Bioenergentics is the study of energy flow in living
systems.
• Since living organisms are highly complicated at
the molecular level, a large amount of energy is
invested in maintaining the ordered and
complicated state of cells and tissues.
• Energy is needed for work and biosynthesis of
cellular structures in a cell.
• Energy is derived from breakdown of fuel
molecules in diet (Catabolism).
• In turn, the energy released is used to drive
biosynthetic processes (Anabolism).
• ATP is used as the energy currency of the cell.
 METABOLIC PATHWAYS
• Catabolism (breakdown of molecules, e.g.,
glycolysis).
• Anabolism (synthesis of molecules, e.g.,
protein synthesis).
 ROLE OF ENZYMES
• Biological catalysts that are able to
speed up or slow down chemical
reactions without a change in
temperature.
• This is important in a living system since
heat can damage tissues.
• For a chemical reaction to happen in a
cell, activation energy is required, which
actually represents the energy needed
to break chemical bonds in reactants.
• Enzymes act as catalysts and lower the
activation energy needed to start a
reaction, so that reaction can proceed
efficiently (without a change in
temperature).
 BIOCHEMISTRY IN MEDICINE &
HEALTHCARE
• Biochemistry, medicine, and other health care disciplines are intimately related.
• Health in all species depends on a harmonious balance of the biochemical
reactions occurring in the body, while disease reflects abnormalities in biomolecules,
biochemical reactions, or biochemical processes.
• Examples of disturbances in human biochemistry responsible for diseases or other
debilitating conditions include electrolyte imbalance, defective nutrient ingestion or
absorption, hormonal imbalances, toxic chemicals or biologic agents, and DNA-
based genetic disorders.
• Biochemical approaches are often fundamental in illuminating the causes of
diseases and in designing appropriate therapy.
• Biochemical laboratory tests also represent an integral component of diagnosis and
monitoring of treatment.
• A sound knowledge of biochemistry and of other related basic disciplines is essential
for the rational practice of medicine and related health sciences.
BIOCHEMISTRY IN MEDICINE &
HEALTHCARE
 BIOCHEMISTRY IN MEDICINE &
HEALTHCARE
• Clinical diagnostics (blood tests, enzyme assays).
• Nutritional biochemistry (metabolic diseases like diabetes).
• Genetic disorders and molecular medicine (e.g., sickle cell
anemia).
• Pharmacology (drug design and metabolism).
 BIOCHEMISTRY IN MEDICINE &
HEALTHCARE
• Biochemistry, medicine, and other health care disciplines are intimately
related.
• Health in all species depends on a harmonious balance of the biochemical
reactions occurring in the body, while disease refects abnormalities in
biomolecules, biochemical reactions, or biochemical processes.
• Biochemical approaches are often fundamental in illuminating the causes of
diseases and in designing appropriate therapy.
• Biochemical laboratory tests also represent an integral component of
diagnosis and monitoring of treatment.
• A sound knowledge of biochemistry and of other related basic disciplines is
essential for the rational practice of medicine and related health sciences.
 SUMMARY AND KEY TAKEAWAYS
• Biochemistry is essential for understanding life processes.
• Biomolecules (carbohydrates, proteins, lipids, nucleic acids)
have diverse functions.
• Bioenergetics explains how cells obtain and use energy.
• Biochemistry is crucial in diagnosing and treating diseases.
 REFERENCES & FURTHER READINGS

Books:
Chapter 1: Biochemistry in Medicine. Harper’s illustrated
biochemistry (32nd edition).
Online resources:
Introduction to Biochemistry by Easy Peasy
(https://www.youtube.com/watch?v=91IuG_Hx9i4)
Biomolecules (Updated 2023) by Amoeba Sisters
(https://www.youtube.com/watch?v=1Dx7LDwINLU)
QUESTIONS & DISCUSSION