Biomolecules||Part-I||Plus One Biology||Zoology||Chapter-9||NEET Biology||K-TET NS Exam

 

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In this session Bio Strips Media takes through the important topics of Biomolecules. It is one of the most important and scoring topics in Plus One Biology Exam and NEET Exam. 

 

This lecture covers:

·         Biomolecules

·         How to analyze chemical composition?

·         Organic and inorganic molecules

·         Micro and macro molecules

Chemicals of living and nonliving Systems

If we perform elemental analysis of a plant tissue,  animal tissue, microbial paste( living matter ) and of a piece of earth's crust (non living matter), we find that all living and nonliving systems are  made up of same chemicals, elements (carbon  hydrogen, oxygen and several others) and compounds and their chemicals follow the same set of rules. Close examination however has indicated that most living organisms have relatively high abundance of carbon and hydrogen than in Earth's crust. Further living organisms are composed mainly of water whereas the non living systems may or may not contain water.

Biomolecules

Biomolecules are chemicals or molecules present in the  cells of living organisms.

Cellular pool

The collection or  sum total of different types of biomolecules compounds and ions present in a Cell is called a cellular pool.

Biomolecules are of two types: inorganic and organic

Inorganic compounds

The inorganic compounds usually lack the element carbon. They have relatively small molecules with simple structure and low molecular weights. They include water, mineral Salts and ions and gases.

Organic compounds

The organic compounds contain the element carbon. They have large molecules with Complex structure and high molecular weights. They include carbohydrates ,lipids, proteins, amino acids, nucleic acids, nucleotides and vitamins.

How to analyse chemical composition?

To obtain organic compounds one has to perform a chemical analysis. Take any living tissue (a piece of liver or a piece of vegetable  etc.) grind it in tri chloro acetic acid using a mortar and pestle to obtain a thick salary. Now  filter it through a cheesecloth or cotton. We could obtain filtrate( acid soluble pool ) and the retentate( acid insoluble fraction ). Scientists have been able to extract a large number of organic compounds in the acid soluble pool by using different separation techniques.

To analyse inorganic elements and compounds weigh a small amount of a living tissue (leaf or liver ) and dry it . All the water is evaporated and the remaining material gives the dry weight. Burn the tissue so that all the organic compounds are oxidized to gaseous form. (carbon dioxide and water vapour) and are removed. The material left is termed Ash, which contains inorganic elements (calcium, magnesium, etc). Inorganic compounds like sulphate, phosphate, etc can also be identified in the acid soluble fraction.

Micromolecules and Macromolecules

Chemical compounds found in living organisms are of two types, micromolecules and macromolecules.

Micro molecules

 The micromolecules are small in size and low molecular weights( less than thousand daltons ) simple molecular structure and often high solubility in the intracellular fluid. These include inorganic compounds such as water, mineral salts, and gases as well as organic compounds like Sugars, lipids, amino acids and nucleotides.

 The micromolecules act as building blocks for the macromolecules.

Macromolecules

The macromolecules are large in size have high molecular weights  (usually 10000 daltons and above),  Complex molecular structure and colloidal state being insoluble in intracellular fluid. They include organic compounds like polysaccharides, proteins and nucleic acids. 

Lipid molecules may be large but are usually not large enough to be considered macromolecules.