Chromosomes can be found in the nucleus of every plant and animal cell; these combinations of DNA and protein are essential components of genetic information. DNA is a long chain of genetic information that would not be able to fit inside a cell without the structural assistance of chromosomes, and this information helps determine a plant or animal's individual traits, including physical characteristics and behavioral capabilities. The DNA that is contained in chromosomes is passed from parents down to offspring.
All plant and animal tissue is made up of microscopic cells, and each of of these tiny cells has a nucleus, which is not only the center of genetic information but also the closest thing a cell has to a brain. Nuclei are responsible for gene regulation, a function that separates eukaryotic cells, a cell type that includes plant, animal and fungal cells, from other cell types.
Even single-celled organisms, such as bacteria can have chromosomes. Chromosomes vary in shape and form across different life forms. For example, human chromosomes have a linear structure that manifests in an x shape while some bacteria have circular chromosomes. Though humans are more genetically complex than bacteria, human chromosomes are actually shorter in length than that of bacteria.