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Biomolecules PDF Notes, Important Questions and Synopsis



  • All the carbon compounds which we get from living tissues can be called biomolecules.
  • Macromolecules and their Functions





  • Mainly compounds of C, H and O.

  • Homopolysaccharides: Made of only 1 type of monosaccharide monomer (e.g. starch, glycogen, cellulose, chitin, insulin).

  • Heteropolysaccharides: Made of more than 1 type of monosaccharide monomer.

  • Starch, glycogen - Storage food in plants and animals.

  • Cellulose, chitin - Provide a framework to cells.


  • Mainly fats and their derivatives.

  • Simple lipids contain 1 molecule of glycerol and 3 molecules of long chain fatty acids.

  • Conjugated lipids contain other substances such as a phosphate group, protein molecule or carbohydrate molecule.

  • Derived lipids are formed or derived by the hydrolysis of simple or conjugated lipids.


  • Fats are oxidised to obtain energy.
  • They also act as food reserves.


Nucleic acids

  • Composed of polynucleotide chains - pentose sugar, nitrogenous base, phosphoric acid.

  • DNA - Contains deoxyribose pentose sugar

  • RNA - Contains ribose pentose suga

  • DNA acts as the genetic material
  • RNAs show enzymatic activities


  • Folded linear heteropolymers of amino acids.

  • Primary structure: Sequence of amino acids in a polypeptide chain of a protein.

  • Secondary structure: Formation of hydrogen bonds between carboxyl oxygen and hydrogen atoms of other amino acids belonging either to the same polypeptide chain or to a different polypeptide chain.

  • Tertiary structure: Long protein polypeptide chains fold and bend on themselves extensively.

  • Quaternary structure: Each polypeptide chain is a subunit of the protein molecule.

  • Transport of nutrients across the cell membrane
  • Fighting infectious agents
  • Act as hormones and enzymes
  • Anabolism is the process by which large, complex molecules are made of simpler molecules.
  • Catabolism is the process by which large complex molecules are broken down into small, simpler compounds.
  • The rate of reaction refers to the amount of product formed per unit.
  • Rate = δp/δt
  • To initiate any chemical reaction, the substrate acquires a certain amount of energy which is called energy of activation.
  • When the substrate is bound to the enzyme’s active site, a new structure called the transition state structure is formed.

  • Mechanism of Enzyme Action

  • Factors Affecting Enzyme Activity

  • Classification and Nomenclature of Enzymes

  • Some enzymes are associated with non-protein substances which make the enzyme catalytically active. Such non-protein groups are called co-factors.
    • Prosthetic group (e.g. peroxidase has haem as the prosthetic group)
    • Co-enzymes (e.g. Coenzyme A)
    • Metal ion (e.g. zinc associates with carboxypeptidases)


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