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09 BIOMOLECULES
56 BIOMOLECULES SCAN CODE Biomolecules Chapter 09 Biomolecules Fig 9.1: Biomolecules 1. The Cellular Pool  A cell is made up of thousands of chemicals. The structure and function of different cell constituents are an interplay of their constituent chemicals, their management and properties.  Carbon containing compounds that are involved in metabolic processes of living organisms are called biological molecules or biomolecules.  The collection or sum total of different types of biomolecules, compounds and ions present in the cell is called a cellular pool.  All the elements present in a sample of earth’s crust are also present in a sample of living tissue.  However, carbon and hydrogen are present in abundance with respect to other elements in any living organism than in earth’s crust. Fig 9.2: Elemental composition in earth’s crust and human body
BIOMOLECULES 57 SCAN CODE Biomolecules  All the carbon compounds that are present in living tissues can be called ‘biomolecules’. A comparison of Elements present in non-living and living matter Elements % Weight in Earth’s crust % Weight in Human body Hydrogen (H) 0.14 0.5 Carbon (C) 0.03 18.5 Oxygen (O) 46.6 65.0 Nitrogen (N) Very little 3.3 Sulphur (S) 0.03 0.3 Sodium (Na) 2.8 0.2 Calcium (Ca) 3.6 1.5 Phosphorus (P) 0.105 1.1 Magnesium(Mg) 2.1 0.1 Silicon (Si) 27.7 Negligible 2. Analysis of Chemical Composition  Elemental analysis gives elemental composition of living tissues in the form of hydrogen, oxygen, chlorine, carbon etc.  Analysis for compounds gives an idea of the kind of organic and inorganic constituents present in living tissues. 2.1 Analysis of Organic Compounds  A chemical analysis is performed for identification of types of organic compounds found in living organisms.  Trichloroacetic acid is used in biochemistry to precipitate macromolecules such as DNA, RNA, and proteins. Fig 9.3: Experiment of elemental analysis for identification of organic compounds
58 BIOMOLECULES SCAN CODE Biomolecules Fig 9.4: The flowchart showing the procedure for analysis of chemical composition  Acid soluble fraction or filtrate have all compounds with molecular weights ranging from 18-800 daltons.  Acid insoluble fraction or retentate have compounds with molecular weights in the range of 10,000 daltons and above (some exception exists).  Analytical techniques are used in analysis of an organic compound and these give an idea of the molecular formula and the probable structure of that compound. 2.2 Analysis of Inorganic Compounds  Living organisms have also got inorganic elements and compounds in them. Fig 9.5: Elemental analysis of dried leaves A living tissue (either plant or animal) is taken and ground in trichloroacetic acid (CCl3COOH) using a mortar-pestle A thick slurry is obtained which is strained through cheesecloth Two fraction are obtained after straining Filtrate (Acid-soluble pool) Thousands or organic compounds were found in filtrate Retentate (Acid-insoluble fraction)