Chromosome

DNA is a molecule that carries the cell's genetic information. All the proteins that form the cell are written in the DNA. Proteins with their structure and activities form the shape of the cell (e.g. cytoskeletal proteins) and allow its various life processes (such as processing the incoming sugars). For proper function of proteins, they have to be created exactly according to a certain pattern. This pattern is in the DNA and therefore it is very important that the DNA remains intact throughout the life of the cell. Failure of information in the DNA could have far-reaching consequences such as cancer or other serious illnesses. Because DNA is very fragile, it is necessary to be careful not to damage it during its deposition in the cell. In eukaryotic cells, it's solved by wrapping DNA to proteins called histones. Histones are grouped into "packages" of four and the DNA loops around them. These units are then called nucleosomes. Nucleosomes further attach to each other and form a thickened spiral. This produces chromatin - material from which the chromosomes are composed. Chromosomes are stored in the cell core and in different organisms, there is a different number of chromosomes. For example, humans have 46 chromosomes in a diploid state, the fruit fly has only 8, while dogs have 78 chromosomes.