Biochemistry of cell

Metabolism

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.

Biomolecules

• 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.
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• 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

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• 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.

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• Nucleotides = Nucleosides + Phosphate groups

  OR
  Nitrogenous base + Sugar + Phosphate group
  e.g., adenylic acid, thymidylic acid, guanylic acid, uridylic acid and cytidylic acid.  !--

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• 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…