Components of a living Body:
All living systems are built composed of atoms and molecules. The biomolecules determine the structure and functions of different cells. The cellular pool is composed of both inorganic and organic molecules. Biomolecules are micromolecules and macromolecules.
Inorganic Compounds:
1. Water: It constitutes 60-80% of the cell contents and 75-90% of the protoplasm. Water is an abundant compound of living beings and most intracellular reactions occur in an aqueous environment. Life on Earth began in the ocean.
2. Minerals: Minerals constitute about 1-3% of the cell contents but are very essential for life activities. Essential minerals required in large quantities for proper growth and metabolism are called macronutrients. They include Ca, S, P, Mg, Fe, K, Na, C, etc.
3. Gases: Gases from less than 0.5% of the cell contents. They include O2, CO2, NH3, etc. These gases being soluble in water, occur in a dissolved state.
4. Acids and Bases: Certain chemical compounds release hydrogen ions (H+) when the compounds are placed in water. These compounds are called acids. Certain chemical compounds attract hydrogen atoms when they are placed in water. These substances are called bases.
5. Salts: Salts form by the combination of acid and base through a neutralization reaction. Mineral salts form the solid structure of living things, such as skeletons. These salts are also involved in chemical reactions.
Organic Compounds:
Organic compounds make up about 95% of the dry weight of the protoplasm. It includes smaller molecules and macromolecules.
1. Micro-molecules: These includes inorganic compounds like water, minerals, and gases and organic compounds like sugars, liquids, amino acid,s and nucleotides.
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i. Simple Sugars: Simple sugars are carbohydrates (containing hydrogen and oxygen in the same ratio as water (2:1) and typically can be broken down to release energy in the animal body) that are quickly absorbed by the body to produce energy.
ii. Amino Acids: Amino acids are building blocks of proteins. They are made up of C, H, O, N, and sometimes S. There are 20 amino acids which are normal components of cell proteins. Animals can’t synthesize all the amino acids, they require some in the ready form in the food. These are called essential amino acids.
Example: Lysine, Valine, Tryptophan, etc.
iii. Fatty Acids: Fatty acids are important components of liquids in plants, animals, and microorganisms. Generally, a fatty acid consists of a straight chain of an even number of carbon atoms with hydrogen atoms along the length of the chain and at one end of the chain and a carboxyl group (-COOH) at the other end.
iv. Nucleotides: A nucleotide is an organic molecule made up of a nucleotide base is a five-carbon sugar and one phosphate group. Nucleotides make up the basic units of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) molecules.
2. Micro-molecules: Macromolecules are large, complex, and have high molecular weight. Polysaccharides, proteins, liquids, and nucleic acids are the most important macromolecules. They are polymers of sugars, amino acids, fatty acids, and nucleotides respectively.