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Biochemistry of cell


Analysis of Chemical Composition

  • Chemical analysis is done to find out the types of organic compounds (compounds containing carbons) found in living tissues.

    • Living tissue taken

    • Grinded in trichloro acetic acid to obtain slurry

    • Slurry is filtered to get filtrate (acid-soluble fraction: contains biomacromolecules) and retentate.

    • Thousands of organic compounds found in filtrate

    • Separation techniques used for separating one compound from another

    • Molecular formula and probable structure of the compound found by using analytical techniques

    • All carbon-containing compounds that we get from living tissues are called biomolecules.

  • Analysis of inorganic compounds:

    • Living tissue taken

    • It is dried to evaporate all water, and the remaining material gives its dry weight.

    • The dried material is burnt.

    • All organic compounds are oxidised to gaseous compounds and are removed to leave “ash”.

    • Ash contains many inorganic elements like Ca, Mg, etc.


  • Chemistry point of view: Functional groups like aldehydes, ketones etc., can be recognised

  • Biology point of view: Organic and inorganic constituents of living cells are classified as amino acids, fatty acids, nucleotide bases, etc.
  • Recognition of biomolecules, which can be micromolecules or macromolecules
  • Molecules with weight more than thousands − biomacromolecules

  • Molecules with weight less than thousands − biomicromolecules

Amino Acids

  • In these compounds, α-carbon has the substituents as hydrogen, carboxyl group, amino group and a variable group R.

  • Based on the R group, there are 20 amino acids
    When R is H − glycine (the simplest amino acid)
    When R is CH3 − alanine

  • The chemical and physical properties of amino acids depend upon their amino group, carboxyl group and R group.

  • Based on the number of amino and carboxyl groups, amino acids could be acidic (glutamic acid), basic (lysine) or neutral (valine).

    • More carboxylic group − acidic amino acid

    • More amino group − basic amino acid

    • Equal amino and carboxylic groups − neutral amino acid

  • Aromatic amino acids − e.g., tyrosine, phenylalanine and tryptophan

  • At different pH, the structures of amino acids change because of ionisable nature of −NH2 and −COOH groups.

Fatty Acids

  • Have carboxylic group linked to an R group; R (any −CH2 group with 1 to 19 carbons)

  • Fatty acids could be saturated (without double bond) or unsaturated (with double bond)

  • Glycerol − this is trihydroxy propane

  • Lipids have both fatty acids and glycerol, and based on the number of glycerols, lipids could be monoglycerides, diglycerides, triglycerides, etc.

  • Some lipids are phosphorylated; they contain phosphorus, e.g., lecithin

Nitrogenous Bases

  • Carbon compounds with heterocyclic rings; e.g., adenine, thymine, guanine

  • Nucleosides = Nitrogenous Bases + Sugar
    e.g., adenosine, thymidine, guanosine, uridine and cytidine.

  • Nucleotides = Nucleosides + Phosphate groups

    Nitrogenous base + Sugar + Phosphate group
    e.g., adenylic acid, thymidylic acid, guanylic acid, uridylic acid and cytidylic acid.  !--
  • Nucleic acids like DNA and RNA are polymers of nucleotides.


Analysis of Chemical Composition

  • Chemical analysis is done to find out the types of organic compounds (compounds containing carbons) found in living tissue…

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