The nucleus of eukaryotes contain the DNA organized into separate chromosomes. (Mitochondria also contain a small amount of DNA,which is therefore known as non-chromosomal DNA.) In a human diploid ce8ll thete are 23 pairs of chromosomes giving a diploid number of 46, with half as many in a haploid cell. Cells with more than the normal complement of DNA are said to be polyploid when they contain more than the usual number of standard chromosomes. The nucleolus is a region within the nucleus,in which the genes for 3 of the ribosomal RNA molecules are located. The nuclear membrane is double-layered with a perinuclear space. Transfer of substances between the cytplasm and nucleus is through the nuclear pore,which is a complex of proteins in an octagonal array with a central hole. The proteins synthesized in the cytoplasm move into the nucleus, while the RNA synthesized within the nucleus moves out to the cytoplasm. The lamina is a structure that surrounds the inner nuclear membrane and c