Biomolecules

• Biomolecules are the molecules present in living systems like carbohydrates, proteins, nucleic acids, lipids, vitamins etc which are essential for the growth and maintenance of our body.
• Carbohydrates are hydrates of carbon and most have a general formula C x (H 2 O) y.
• Carbohydrates can be defined as optically active polyhydroxy aldehydes or ketones or the compounds which produce such units on hydrolysis.
• Some carbohydrates are crystalline, water soluble and sweet in taste, these are called sugars.
• Carbohydrates which are not crystalline, water insoluble and have no sweet taste are called non-sugars.
• Carbohydrates are also called 'Saccharides'.
• Carbohydrates can also be classified based on their reducing character: Reducing sugar and Non-reducing sugar.
• A monosaccharide containing an aldehyde group is known as aldose, while a monosaccharide containing a ketonic group is known as ketose.
• Monosaccharides containing 3 carbon atoms are called triose, 4 carbon atoms are called tetrose etc.
• Glucose (C 6 H 12 O 6 ) is an aldohexose and is also known as dextrose, it is the monomer of starch, cellulose and is probably the most abundant organic compound on earth.
• Glucose can be prepared from sucrose (Cane sugar) by boiling with dilute HCl or H 2 SO 4 in alcoholic solution, resulting in the formation of glucose and fructose in equal amounts.
• Glucose can also be prepared from starch by hydrolysis, commercially it is obtained by boiling starch with dilute H 2 SO 4 at 393 K under pressure.
• The molecular formula of glucose is C 6 H 12 O 6.
• On continuous heating with HI, glucose forms n-hexane.
• Vitamins are classified into two groups depending upon their solubility in water or fat: Fat soluble vitamins (e.g., Vitamins A, D, E, & K) and Water soluble vitamins (e.g., Vitamins B & C).
• Fat soluble vitamins are stored in liver and adipose (fat storing) tissues.
• Vitamin deficiency diseases include Night blindness (Xerophthalmia), Beri-beri, Cheilosis, Convulsions, Pernicious anaemia, Scurvy, Rickets and osteomalacia, Increased fragility of RBCs and muscular weakness, Hemophilia (Increased blood clotting time), and others.
• Denaturation of a protein occurs when it is subjected to physical change or chemical change, causing loss of biological activities.
• Enzymes are biological catalysts, which catalyse different reactions taking place in living body.
• Primary structure of a protein gives the sequence of amino acid molecules in a polypeptide chain.
• Vitamins are designated by alphabets A, B, C, D, etc.
• Water soluble vitamins are readily excreted through urine and cannot be stored (except vitamin B 12) in our body.
• Secondary structure of a protein refers to the shape in which a long polypeptide chain can exist.
• Quaternary structure of a protein refers to the spatial arrangement of sub-units, if any, in the protein.
• Nucleic acids are long chain polymers of nucleotides and are responsible for transmission of heredity.
• The tertiary structure of a protein gives rise to two major molecular shapes - fibrous and globular.
• Tertiary structure of a protein represents overall folding of the polypeptide chains, i.e., further folding of the secondary structure.
• Enzymes are very specific in nature, requiring a small amount of enzyme to catalyse a large amount of reactants.
• Any change in the primary structure of a protein creates a different protein.
• Vitamins are organic compounds required in the diet in small amounts to perform specific biological functions for normal maintenance of optimum growth.
• Almost all the enzymes are globular proteins.
• Secondary structures of proteins arise due to the regular folding of the backbone of the polypeptide chain due to hydrogen bonding between CO and – NH – groups of the peptide bond.
• The simplest amino acid is glycine (H2N-CH2-COOH).
• Carbohydrates are used as storage molecules as starch in plants and glycogen in animals.
• Amino acids can be classified as α, β, γ, δ and so on depending upon the relative position of amino group with respect to carboxyl group.
• Cell wall of bacteria and plants is made up of cellulose.
• Carbohydrate in the form of wood is used for making furniture etc.
• Amino acids are compounds containing amino group (– NH2) and carboxyl (– COOH) group.
• Amylose is a linear polymer of α-D-glucose with C1-C4 glycosidic linkage.
• Except glycine, all other naturally occurring α-amino acids are optically active, since the α-carbon atom is asymmetric.