A section through a eucaryotic
cell, with its prominent
nucleus, in which the long
DNA molecules (carrier of genetic instructions) lie tangled up. Other prominent cell components or
organelles are floating in the endoplasmic fluid between the nucleus and the outer
cell wall. These organelles include the mitochondria (responsible for energy budget), lysosomes (digestion), the reticulum and the
Golgi apparatus. The human body is made of eucaryotic cells, about 100,000,000,000 of them. A comparison of vertebrate embryos at thesame stage of development. (Courtesy: G. Romanes)