Discuss Why Hydrogen Bonding Is Essential for Life

1682 Words Feb 3rd, 2013 7 Pages
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
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For metabolic reactions this is very useful because it means that the enzymes can work at their optimum temperature, often the same as 37C core temperature, and thus the metabolic reactions within the body are very efficient. For every 10C below optimum temperature, the rate of successive substrate-enzyme collisions decreases by 2 to 3 times [Campbell and Reece, p862]. High specific heat capacity also benefits marine environments by resisting temperature fluctuations, which is perhaps why marine food chains are often many times longer than those of terrestrial organisms.

The high heat capacity of water is one of several hydrogen-bonding attributes that benefit the marine environments, unsurprisingly, with the high surface tension and the small relative density of ice also playing a large role in how aquatic organisms survive. The high surface tension of water is perhaps best explained by relating it to close proximity of adjacent water molecules in aqueous solution. This closeness is of course caused by the numerous hydrogen bonds (Fig. 2) existing between the water molecules and is named cohesion, a word that can be defined as being united as a whole.

Fig. 2 numerous hydrogen bonds

As a result of the molecules being united as a whole, the top of a body of water has a membrane that is able to withstand a small downwards force before becoming pierced. The classic