Biology ANALYSIS OF COMPOUNDS

### KEY TOPIC

star Introduction
star Analyzing Organic Components
star Analyzing Inorganic Components

### INTRODUCTION

● There is a color{violet}("wide diversity in living organisms") in our biosphere.

● If we perform such an analysis on a color{violet}("plant tissue, animal tissue") or a color{violet}("microbial paste,") we obtain a list of elements like color{violet}("carbon, hydrogen, oxygen") and several others and their respective content per unit mass of a color{violet}("living tissue.")

● If the same analysis is performed on a piece of color{brown}("earth’s crust") as an example of color{violet}("non-living matter,") we obtain a similar list.

● In absolute terms, color{brown}("no such differences") between the two lists could be made out.

● All the elements present in a sample of color{violet}("earth’s crust") are also present in a color{brown}("sample of living tissue.")

● However, a closer examination reveals that the relative abundance of color{brown}("carbon and hydrogen") with respect to other elements is higher in any living organism than in color{violet}("earth’s crust.")

### ANALYSING ORGANIC COMPONENTS

● One can also find as to what type of color{violet}("organic compounds") are found in color{violet}("living organisms.")

● To get an answer, one has to perform a color{brown}("chemical analysis.")

● We can take any color{brown}("living tissue") (a vegetable or a piece of liver, etc.) and grind it in color{brown}("trichloroacetic acid") (Cl_3C COOH) using a color{violet}("mortar and a pestle.")

● We obtain a color{violet}("thick slurry.")

● If we were to color{violet}("strain") this through a color{violet}("cheesecloth or cotton") we would obtain two fractions.

● One is called the color{brown}("filtrate") or more technically, the color{violet}("acid-soluble pool"), and the second, the color{brown}("retentate") or the color{violet}("acid-insoluble fraction.")

● Scientists have found thousands of color{violet}("organic compounds") in color{brown}("the acid-soluble pool.")

● Then color{violet}("one extracts") the compounds, then subjects the extract to various color{violet}("separation techniques") till one has separated a compound from all other compounds.

● In other words, color{violet}("one isolates") and purifies a compound.

● color{brown}("Analytical techniques"), when applied to the compound give us an idea of the color{violet}("molecular formula ") and the probable structure of the compound.

● All the color{violet}("carbon compounds") that we get from color{violet}("living tissues") can be called color{brown}("‘biomolecules’.")

### ANALYZING INORGANIC COMPONENTS

● However, color{violet}("living organisms") have also gotcolor{violet}(" inorganic elements") and compounds in them.

● A slightly different but color{violet}("destructive experiment") has to be done.

● One weighs a small amount of a color{violet}("living tissue") (say a leaf or liver and this is called color{brown}("wet weight") ) and dry it.

● All the color{violet}("water, evaporates.")

● The remaining material gives color{brown}("dry weight. ")

● Now if the color{violet}("tissue") is fully burnt, all the color{violet}("carbon compounds") are color{brown}("oxidised") to gaseous form (CO_2, water vapour) and are removed.

● What is remaining is called color{brown}("‘ash’.")

● This ash contains color{violet}("inorganic elements") (like calcium, magnesium etc).

● color{violet}("Inorganic compounds") like color{violet}("sulphate, phosphate"), etc., are also seen in the color{violet}("acid-soluble fraction.")

● Therefore elemental analysis gives elemental composition of color{violet}("living tissues") in the form of color{violet}("hydrogen, oxygen, chlorine, carbon") etc. while analysis for compounds gives an idea of the kind of color{violet}("organic and inorganic") constituents present in color{violet}("living tissues.")

● From a chemistry point of view, one can identify color{brown}("functional groups") like color{violet}("aldehydes, ketones, aromatic compounds"), etc.

● But from a color{violet}("biological point") of view, we shall classify them into color{violet}("amino acids, nucleotide bases, fatty acids") etc.