Enzimler are biological molecules that act as catalysts in various chemical reactions within living organisms. They speed up these reactions by lowering the energy required for them to occur, making processes like digestion and metabolism more efficient. Each enzyme is specific to a particular reaction or type of substrate, which is the substance it acts upon. These proteins are essential for life, as they facilitate crucial functions such as breaking down food into nutrients and synthesizing DNA. Without enzymes, many biochemical reactions would occur too slowly to sustain life, highlighting their importance in maintaining biological processes.