Chemical Perspectives in Biology
Chemistry has attained an indisputable position in the field of Biology. The need to study chemical principles and methods has a great role to play in the study of biology. A new field of study called Molecular Biology recently emerged, complementing and overlapping the closely related field of biochemistry.
Chemistry, as such is an investigation of the properties of substances. The chemical properties of biological material can be understood by considering three fundamental particles of matter: protons, neutrons and electrons. These three particles combine to form an atom. The simplest atom hydrogen, has a nucleus, which consists of a single proton and has a single electron orbiting around it. The next larger atom is helium. Its nucleus consists of two neutrons and two protons with two electrons around it. The nuclei of the heavier atoms is similarly composed of increasing numbers of protons, neutrons and electrons.
Chemical Bonds are made by giving up or sharing of electrons. Electrically neutral atoms have equal numbers protons, neutrons and electrons. These seldom occur uncombined with other atoms in biological materials. Many kinds of atoms are more stable after they have gained or lost electrons. The resulting electrically charged particles are called ions. Positive ions are atoms that have lost electrons and Negative ions are atoms which gained electrons. These ions have quite different properties from electrically neutral materials. For example sodium is a soft, white metal. It gives up an electron from each atom upon reaction with chlorine, an odor less, poisonous and green colored gas. These two elements react into the common salt, which is found in many organisms.
A Covalent bonding is another type of chemical bond, is more importantly useful in biology than ionic bonding. In this type of bonding consists of a pair of electrons, one supplied by each of the atoms involved in the bond, travelling in an orbit that includes the nuclei of both atoms. It differs ionic bonding in that electrons are shared between two atoms, but are not transferred between the atoms forming ions. The pair of electrons orbiting around the nuclei of both atoms results in a strong chemical bond that is maintained intact in solution, since it does not depend on electrostatic attractions.
When two or more atoms are joined together, the resulting combination is a molecule. Molecules that consist of only one kind of atom are known as polyatomic elements, example O2 or Oxygen is a diatomic element. A molecule which consists of more than one element or one kind of an atom is called a compound, example H2O or water. Similarly, a glucose molecule consists of Carbon, Hydrogen and Oxygen atoms which are denoted as C6H12O6.
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