Discuss-Hydrophobic, Hydrophilic substances.(Minimum 2 pages)
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Answer:
A hydrophilic
molecule or substance is attracted to water. Water is a polar molecule that acts as a solvent, dissolving other polar and hydrophilic substances. In biology, many substances are hydrophilic, which allows them to be dispersed throughout a cell or organism. All cells use water as a solvent that creates the solution known as cytosol. Cytosol contains many substances, most of which are hydrophilic on at least part of the molecule. This ensures that that can be transported about the cell easily. Substances that are hydrophobic, or repel water, are often transported through and between cells with hydrophilic proteins or structures attached to aid in their dispersal.
Hydrophilic substances diffuse in water, which is to say they move from areas of high concentration to areas of low concentration. This is caused by the attraction of water molecules to the hydrophilic molecules. In areas of high concentration of the molecules, water moves in and pulls the molecules apart. The molecules are then distributed to areas of low concentration, where more water molecules can interact. Diffusion is a very important property of most hydrophilic substances to living organisms. Diffusion allows them to distribute substances with little to no energy on their part.
Examples of Hydrophilic
Sugar
Sugar, or more specifically glucose, is a molecule that many types of cells use as an energy source. A molecule of glucose has both hydrophobic and hydrophilic portions. The picture below shows a molecule of glucose. The black balls are carbon atoms, the red balls are oxygen atoms, and the white balls are hydrogen atoms. Bonds between carbon atoms share electrons equally, and no static electrical charge is created. The oxygen atoms, however, pull an unequal share of electrons from the carbon and hydrogen atoms they are attached to. This property, known as electronegativity, results in the electrons being distributed unevenly, a majority of the time. This causes an electric dipole to form across the bond, creating areas of positive and negative energy. Water can interact with these dipoles, and dissolve glucose.
Definition of Hydrophobic
The word hydrophobic comes from the Greek roots hydro- (meaning water) and -phobia (meaning fearing or hating). The word hydrophobic describes the fact that nonpolar substances don't combine with water molecules. Let's take a closer look at that definition. Water is a polar molecule, which means that it carries a partial charge between its atoms. Oxygen, as an electronegative atom, draws the electrons of each bond closer to its core, thus creating a more negative charge. Therefore, any materials with a charge, be it negative or positive, will be able to interact with water molecules to dissolve. (Think of how salt dissolves in water. This is due to the charges of the ions sodium and chlorine.)
So essentially, hydrophobic molecules are molecules that do not have a charge, meaning they are non-polar. By lacking a charge, these molecules do not have any charge-to-charge interactions that will allow them to interact with water. Hydrophobic materials often do not dissolve in water or in any solution that contains a largely aqueous (watery) environment. This characteristic of being hydrophobic - or non-polar - is important for many of the molecules found in nature, in other organisms, and even within our own bodies.
Examples of Hydrophobic Molecules and Materials
Waxes
Waxes are practical examples of hydrophobic molecules that are used commercially and biologically because of their abilities to resist interacting with water. For example, if you have ever had your car waxed, you probably noticed that the water would bead up and roll off of the paint afterwards. This is because the applied wax is hydrophobic and will not interact with water. Waxes, in this case, help to keep water away from the surface of the car.
Commercial waxes repel water to cause beading.
water beading
On the other hand, in many biological systems, waxes may be used for other means. Some plants, for example, utilize waxes to prevent water from escaping through evaporation. Many of the succulent plants, such as aloe, produce waxes that allow their tissues to retain water for biological use. Still, the reason these plants are able to do so is the hydrophobicity of the waxes.
Hydrophobic and Hydrophilic substances:
The substance which shows high affinity towards water is called as hydrophilic substance. The word meaning of hydrophilic is ‘hydro’ means water whereas ‘philic’ means loving.
On the other hand, the substance doesn’t show affinity towards water is called as hydrophobic substance. The word meaning of hydrophobic is ‘hydro’ means water and ‘phobia’ means fear.
Substance such as salt and soap are hydrophilic in nature, whereas substance such as oil and wax are hydrophobic in nature.