DNA, chromosomes, genes and the genome

All organisms have a genome, and there are similarities and differences between the genomes of different organisms. The genome is made of DNA, wound up into tightly-packed structures called chromosomes. Human body cells have 23 pairs of chromosomes, stored in the nucleus; bacteria have one that is stored in the cytoplasm. Sections of the DNA in chromosomes are called genes, which store instructions for inherited features and life processes. Other sections are non-coding DNA, which contains instructions that controls when the information in genes is used.