<P> The total complement of genes in an organism or cell is known as its genome , which may be stored on one or more chromosomes . A chromosome consists of a single , very long DNA helix on which thousands of genes are encoded . The region of the chromosome at which a particular gene is located is called its locus . Each locus contains one allele of a gene ; however , members of a population may have different alleles at the locus , each with a slightly different gene sequence . </P>
the complete collection of dna and genes is called
chromosome