<Table> <Tr> <Td> Chromosome (10 - 10 bp) DNA Gene (10 - 10 bp) Function A gene is a region of DNA that encodes function . A chromosome consists of a long strand of DNA containing many genes . A human chromosome can have up to 500 million base pairs of DNA with thousands of genes . </Td> </Tr> </Table> <Tr> <Td> Chromosome (10 - 10 bp) DNA Gene (10 - 10 bp) Function A gene is a region of DNA that encodes function . A chromosome consists of a long strand of DNA containing many genes . A human chromosome can have up to 500 million base pairs of DNA with thousands of genes . </Td> </Tr> <P> In biology, a gene is a sequence of DNA or RNA that codes for a molecule that has a function . During gene expression, the DNA is first copied into RNA . The RNA can be directly functional or be the intermediate template for a protein that performs a function . The transmission of genes to an organism's offspring is the basis of the inheritance of phenotypic traits . These genes make up different DNA sequences called genotypes . Genotypes along with environmental and developmental factors determine what the phenotypes will be . Most biological traits are under the influence of polygenes (many different genes) as well as gene--environment interactions . Some genetic traits are instantly visible, such as eye color or number of limbs, and some are not, such as blood type, risk for specific diseases, or the thousands of basic biochemical processes that constitute life . </P> <P> Genes can acquire mutations in their sequence, leading to different variants, known as alleles, in the population . These alleles encode slightly different versions of a protein, which cause different phenotypical traits . Usage of the term "having a gene" (e.g., "good genes," "hair colour gene") typically refers to containing a different allele of the same, shared gene . Genes evolve due to natural selection or survival of the fittest of the alleles . </P>

When was the location of genetic information on chromosomes established