CSIR NET life science 2014 notes part 1

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