Discuss Why Hydrogen Bonding Is Essential for Life
Discuss why hydrogen bonding is essential for life
Throughout biochemistry there are many bonds without which life as it is on earth today would not be possible. One of the most important bonds of these is the hydrogen bond, a weak chemical bond that is present in essential biological molecules such as water and polypeptides. A hydrogen bond is defined by Campbell and Reece as occurring when a hydrogen atom is covalently bonded to an electronegative atom but attracted to another electronegative atom. In water molecules, there are several key reasons why hydrogen bonds can be formed and explaining them in water a good way to show the chemistry. Firstly, the presence of covalent bond between the hydrogen and the oxygen means that the electrons in the outer shells of both atoms are shared- 1 electron from hydrogen and 1 electron from oxygen. Since the 2 electrons are shared, they are free to move within the covalent bond to the atom that is the most electronegative. In the case of water, this is oxygen. As a result of the electrons moving to the oxygen side of the bond, the hydrogen becomes less electron-dense and becomes a slight positive charge known as a delta-positive charge. It is this positive charge that has the ability to attract other negatively charged objects, since opposite electrostatic charged atoms attract each other. On the oxygen atom of each water molecule there is a lone pair of electrons that are negatively charged, which makes oxygen delta-negative. This means that between water molecules, the delta-positive hydrogen of one molecule is able to attract a lone pair of electrons from the delta-negative oxygen atom of another water molecule (Fig. 1).
Fig. 1 Hydrogen bonding in water
A hydrogen bond, however, is comparatively weak to covalent or ionic bond, as much as 22 times time weaker [Libes 2009], so in order to explain why hydrogen bonds are so necessary in life it is perhaps not significant that hydrogen bonds are weak on their own, since the
Throughout biochemistry there are many bonds without which life as it is on earth today would not be possible. One of the most important bonds of these is the hydrogen bond, a weak chemical bond that is present in essential biological molecules such as water and polypeptides. A hydrogen bond is defined by Campbell and Reece as occurring when a hydrogen atom is covalently bonded to an electronegative atom but attracted to another electronegative atom. In water molecules, there are several key reasons why hydrogen bonds can be formed and explaining them in water a good way to show the chemistry. Firstly, the presence of covalent bond between the hydrogen and the oxygen means that the electrons in the outer shells of both atoms are shared- 1 electron from hydrogen and 1 electron from oxygen. Since the 2 electrons are shared, they are free to move within the covalent bond to the atom that is the most electronegative. In the case of water, this is oxygen. As a result of the electrons moving to the oxygen side of the bond, the hydrogen becomes less electron-dense and becomes a slight positive charge known as a delta-positive charge. It is this positive charge that has the ability to attract other negatively charged objects, since opposite electrostatic charged atoms attract each other. On the oxygen atom of each water molecule there is a lone pair of electrons that are negatively charged, which makes oxygen delta-negative. This means that between water molecules, the delta-positive hydrogen of one molecule is able to attract a lone pair of electrons from the delta-negative oxygen atom of another water molecule (Fig. 1).
Fig. 1 Hydrogen bonding in water
A hydrogen bond, however, is comparatively weak to covalent or ionic bond, as much as 22 times time weaker [Libes 2009], so in order to explain why hydrogen bonds are so necessary in life it is perhaps not significant that hydrogen bonds are weak on their own, since the