Chemical Basis of Life
Example − Synapse. Illustration of a synapse, the junction between two nerve cells. Synapses transmit electrical (chemical) signals from one nerve cell to the next. When an electrical signal reaches a synapse it triggers the release of chemicals called neurotransmitters (red) from vesicles (pink) in the terminal swelling of the presynaptic cell. The vesicles burst through the membrane and neurotransmitters cross a microscopic gap called the synaptic cleft, and bind to the receptor nerve cell. The neurotransmitter changes the permeability of the postsynaptic membrane, causing it to propagate an electrical impulse.
Macromolecules are the most interesting and characteristic molecules of living systems; in a true sense, the evolution of life as we know is the evolution of macromolecular structures.
Living beings are like factories, which need easily available raw materials. Just as factories need machines, the machines of living organisms are specific protein molecules called enzymes. Enzymes cause chemical changes to convert food into body parts such as tissues, the muscle etc. All this doesn’t happen in a single step, but along an assembly line called "metabolic pathway".
Our energy is obtained by burning fuel. The three major constituents of our food namely carbohydrates, fats and proteins function as fuels, as well as provide raw materials for building our tissues.
To understand life, we need to know about the chemical properties and reactions of the organic compounds that make us. DNA provides the molecular basis of the template needed for genetic replications. With this discovery, the field of molecular biology was born − the field essentially owes its origin to chemical basis of life.