NEET Biology Notes Biomolecules and Enzyme
Chemical Constituents of Living Cells
Most of the elements present in earth’s crust are also present in the body of living things or living tissues. On analysis, it is found that relative quantity of carbon and hydrogen with respect to other elements is more in any living organism. All the carbon compounds that we get in living tissues are called biomolecules. Living organisms also have inorganic elements and compounds in them. The elemental analysis gives elemental composition of living tissues in the form of hydrogen, oxygen, chlorine, carbon, etc. From the biological point of view, we shall classify all the analysed elements as amino acids, nucleotide bases, fatty acids, etc.
Primary and Secondary Metabolites
Metabolites are those biomolecules which are either utilised in metabolic functions or synthesised by the cellular machinery. These are of two types :
- The primary metabolites in an animal tissue are sugars, amino acids, fatty acids, fats and oils, nucleosides and nucleotides.
- In plants, fungal and microbial cells, there are thousands of compounds other than primary metabolites, e.g. alkaloides, flavonoides, rubber, essential oils, antibiotics, coloured pigments, scents, gums, spices. These are called secondary metabolites.
- Secondary metabolites are organic compounds that are not directly involved in the normal growth and development or reproduction of an organism.
- Secondary metabolites are often restricted to a narrow set of species with in a phylogenetic group.
- Secondary metabolites often play an important role in plant defense against herbivory and other interspecies defenses.
Biomolecules
Biomolecules (chemical compounds) found in living organisms are of two types
- Microbiomolecules
The molecules, which have molecular weights less-than one thousand dalton and are usually referred to as micromolecules or simply biomolecules.
- Macrobiomolecules
The molecules which are found in the acid insoluble fraction are called biomacromolecules. The chemical composition of living tissue from abundance point of view is given below
