Physical and chemical concepts for CSIR NET
Properties of Water
- Water is the most abundant substance in living organisms,more than 70% weight of an organism.
- Water molecule is tetrahedron in nature,109 degree angle.
- Ionized water molecule influences self assembly, structure,function among many organic molecule such a lipid ,protein ,carbohydrates etc.
- Higher melting point,boiling point,heat of vaporization is higher as well
- Water is dipole in nature the dielectric constant of water is 78.5.
- Due to strong dipole nature and high dielectric constant water can dissolve large quantities of charged substance such a salts like NaCl.
- Polar molecule readily dissolve in water as they can replace water-water interaction .
- lifetime of each hydrogen bond is 1-20 picoseconds.
Water influences the structure of Biomolecules
- Water influences the biomolecular structures.
- Covalent bond is the strongest bond that holds the molecule.
- Folding of Biomolecules is affected by water,many biomolecules are amphipathic in nature.
- Amino acids with charged side chains such as Arginine,glutamate,serine generally present on the surface in contact with water
- Water can simultaneously act as a hydrogen donor and acceptor as well
- Bond energies of atoms
| kcal/mole | |
| C-H | 98 |
| O-H | 110 |
| C-C | 80 |
| C-O | 78 |
| H-H | 103 |
| C-N | 65 |
| O=O | 116 (2 x 58) |
| C=O | 187* (2 x 93.5) |
| C=C | 145 (2 x 72.5) |
I will update it further on Composition,structure and function of Biomolecules