Cellular DNA is the information source for making proteins in the cell. A section of DNA that provides information for one protein is called the gene for that protein. Genes are sections or segments of DNA that are carried on the chromosomes and determine specific human characteristics, such as height or hair color. proteins control the characteristics.
Heredity is the passing of genes from one generation to the next. Genes hold the instructions for making protein products (like the enzymes to digest food or the pigment that gives your eyes their color). As your cells duplicate, they pass this genetic information to the new cells.
But genes do not carry out the actual work. Rather, they serve as instruction books for making functional molecules such as ribonucleic acid (RNA) and proteins, which perform the chemical reactions in our bodies. It is these proteins which carry out the actual function of performing different functions and controlling various characteristics. So genes produce the proteins which in turn controls the characteristics, or traits.
Example: Plant height is dependent on the amount of a particular plant hormone. The amount of the plant hormone made will depend on the efficiency of the process for making it. Consider now an enzyme that is important for this process. If this enzyme works efficiently, a lot of hormone will be made, and the plant will be tall. If the gene for that enzyme has an alteration that makes the enzyme less efficient, the amount of hormone will be less, and the plant will be short.