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Hydrogen Bonds in Biology

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Explain the chemical basis of hydrogen bond formation in biology. Discuss the role of hydrogen bonding in the structure and function of biological macromolecules. Your essay should refer to DNA, RNA and proteins.
A hydrogen bond is a particularly strong type of intermolecular force which is essential in many biological macromolecular structures and is formed when a hydrogen atom from one molecule covalently bonds to a highly electronegative atom on another molecule, usually nitrogen, fluorine or oxygen. The bond is a particular case of dipole dipole attractions where the large electronegativity difference between the small hydrogen atom and the nitrogen, fluorine or oxygen atom results in the electron pair being pulled away from the hydrogen. Given its small size and the fact that it has no other electrons to shield the nucleus, the hydrogen atom exerts a strong attractive force on a lone pair in the electronegative atom of a neighboring molecule. Hydrogen bonds play a key role in ensuring that many biological molecules adopt and subsequently retain their correct three dimensional structure. This is particularly the case in proteins and nucleic acids. Therefore this essay will examine the importance of hydrogen bonds in the nucleic acids RNA and DNA and finally their role in protein structure.
It is important to understand the chemical basis of a hydrogen bond before moving on to explain their significance. As already described, the small hydrogen atom exerts a strong attractive force on the lone pair of the electronegative atom on the neighboring molecule. The electronegative atom to which hydrogen is bonded to causes an uneven distribution of electrons between the two atoms, so the hydrogen atom carries a partial positive charge. This partial positive charge facilitates electrostatic attraction between the hydrogen atom and another electronegative atom. The...

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