Hsslive-03-biomolecule-1-signed

Page 1: Biomolecule Introduction

  • Living organisms are composed of different types of compounds.

  • Chemical analysis shows they are made of elements like Carbon (C), Hydrogen (H), and Oxygen (O).

    • Non-living matter also contains these elements.

    • Living things generally have higher relative abundance of C and H than non-living things.

Analyzing Chemical Composition

  • Methods to assess the chemical composition of living tissue:

    • Grind a sample (e.g., vegetable or liver) in trichloroacetic acid (Cl3CCOOH).

    • Obtain two fractions by straining:

      1. Filtrate (acid-soluble pool) - Contains micromolecules/biomolecules.

      2. Retentate (acid-insoluble fraction) - Contains biomacromolecules.

a) Acid Soluble Pool

  • Thousands of organic compounds found; molecular weights range from 18 to 800 daltons.

  • Micromolecules have molecular weights < 1000 Da.

b) Acid Insoluble Pool

  • Contains four types of organic compounds:

    • Proteins

    • Nucleic acids

    • Polysaccharides

    • Lipids (molecular weight ≤ 800 Da)

  • Lipids form vesicles upon membrane disintegration during the analysis.

  • Molecular Weight of acid insoluble fraction > 10,000 Da.

Analysis of Inorganic Elements

  • Living tissues also contain inorganic elements/compounds:

    • Measure wet weight of tissue, dry it to obtain dry weight after evaporation of water.

    • Burn tissue to oxidize carbon compounds (producing CO2 and H2O), leaving ash containing inorganic elements (e.g., calcium, magnesium).

    • Acid-soluble fraction can include inorganic compounds (e.g., sulfate, phosphate).

    • Represents the cytoplasmic composition of living tissues.

Page 2: Primary and Secondary Metabolites

Types of Metabolites

  • Organic compounds used in cellular metabolism:

    1. Primary Metabolites

      • Essential for cell growth; produced continuously during growth (e.g., proteins, nucleic acids, polysaccharides).

    2. Secondary Metabolites

      • Derived from primary pathways; not essential for cell survival. Examples include alkaloids, toxins, steroids, essential oils.

Amino Acids

  • Building blocks of proteins; contain:

    • Amino group, carboxyl group, and a variable R group on α-carbon.

    • Classified by:

      1. Nature of R group:

        • Acidic (e.g., glutamic acid), Basic (e.g., lysine), Neutral (e.g., valine).

      2. Functional classification:

        • Essential vs. Non-essential amino acids.

Zwitter Ion

  • Amino acids can exist as dipolar ions (zwitter ions) at specific pH (isoelectric point).

Page 3: Proteins

Structure of Proteins

  • Polypeptides formed from amino acids linked by peptide bonds (formed through dehydration reaction).

  • Types of Protein Structure:

    1. Primary Structure:

      • Sequence of amino acids in a linear fashion (N-terminal to C-terminal).

    2. Secondary Structure:

      • Coiling or folding into alpha helices or beta-pleated sheets.

    3. Tertiary Structure:

      • 3D structure formed when polypeptide folds upon itself.

    4. Quaternary Structure:

      • Association of multiple polypeptide chains (e.g., hemoglobin with 2 α and 2 β chains).

Functions of Proteins

  1. Structural components (e.g., collagen).

  2. Hormones (e.g., insulin).

  3. Transport molecules (e.g., GLUT-4 for glucose).

  4. Immune response (e.g., antibodies).

  5. Enzymatic catalysis (e.g., trypsin).

  6. Sensory reception (e.g., taste, smell).

Page 4: Lipids

Definition and Structure

  • Lipids are hydrophobic (water insoluble).

    • Composed of fatty acids (saturated vs. unsaturated).

    • Structure includes:

      • Fatty Acids: carboxyl group + R group (length varies).

      • Glycerol: trihydroxy propane.

Types of Lipids

  • Triglycerides: energy storage (fats and oils).

    • Monoglycerides (1 fatty acid + 1 glycerol).

    • Diglycerides (2 fatty acids + 1 glycerol).

    • Triglycerides (3 fatty acids + 1 glycerol).

  • Phospholipids: major component of cell membranes (e.g., lecithin).

Polysaccharides

  • Long chains of monosaccharides:

    1. Cellulose: Homopolymer of glucose (plant cell walls).

    2. Starch: Energy storage in plants (homopolymer of glucose).

    3. Glycogen: Energy storage in animals (homopolymer of glucose).

    4. Chitin: Complex polysaccharide (exoskeletons of arthropods).

Page 5: Nucleic Acids

Definition and Structure

  • Nucleic acids are macromolecules involved in genetic information storage (DNA and RNA).

    • Formed of nucleotides consisting of:

      • Nitrogen base (purines: adenine, guanine; pyrimidines: uracil, cytosine, thymine).

      • Sugar (deoxyribose in DNA, ribose in RNA).

      • Phosphate group.

DNA Structure

  • Double helix formed by two strands of nucleotides.

  • Complementary base pairing (A-T, G-C) with hydrogen bonds.

Page 6: Metabolism

Definition

  • Total of all chemical reactions in living organisms (catabolism + anabolism).

Metabolic Pathways

  • Series of linked biochemical reactions, similar to city traffic systems.

  • Each reaction is catalyzed by enzymes.

  • Examples:

    1. Glycolysis: Glucose to pyruvic acid via ten enzymatic steps.

    2. Fermentation in yeast: Glucose to ethanol.

    3. Anaerobic respiration: Glucose to lactic acid in muscles.

Page 7: Enzymes

Function and Characteristics

  • Biological catalysts promoting biochemical reactions, mostly proteins.

  • Substrate specificity and action involves:

    1. Binding at the active site.

    2. Formation of enzyme-substrate complex.

    3. Conversion to product and release.

Factors Affecting Enzyme Activity

  • Temperature and pH:

    • Optimum conditions required for maximal activity.

    • High temperatures can denature enzymes.

  • Substrate Concentration:

    • Higher concentration increases reaction rate until saturation.

  • Enzyme Inhibition:

    • Competitive inhibitors resemble substrate and reduce activity.

Classification of Enzymes

  1. Oxidoreductases: Catalyze redox reactions.

  2. Transferases: Transfer functional groups.

  3. Hydrolases: Catalyze hydrolysis reactions.

  4. Lyases: Remove groups to form double bonds.

  5. Isomerases: Catalyze structural isomerization.

  6. Ligases: Join two compounds.

Page 8: Cofactors

Definition

  • Non-protein components enhancing enzyme activity.

Types of Cofactors

  1. Prosthetic groups: Tightly bound (e.g., heme in catalase).

  2. Coenzymes: Loosely bound (e.g., NAD, derived from vitamins).

  3. Metal ions: Essential for enzyme function (e.g., Zn in carboxypeptidase).

Page 9: Previous Years Question Highlights

  1. Most abundant protein in the animal world?

  2. Identify diagrams related to protein structure levels.

  3. Write the general formula of an amino acid.

  4. Discuss the graph related to enzyme activity.

  5. Explain specific enzyme action and factors that affect it.

Page 10-13: Additional Questions for Review

  • Include fill-in-the-blanks, identification tasks, wrong statement corrections, enzyme classes identification, etc.

  • Encourage understanding of biochemical processes linked to previous discussions.