Genes are the physical and functional unit of heredity, which carry information from one generation to the next. A gene is a sequence of nucleotides (a sequence on DNA or RNA), which is located on a certain position in the whole DNA. The DNA again is distributed over the chromosomes. A gene encodes for a certain product, for example, a protein. That protein again is involved in a certain process that determines a particular trait or character, for instance, the colour of a flower. If this gene is deleted or mutated in any form the protein will not be produced or changed in its function, so this will influence the colour of the plant. The genes are located in the chromosomes.