Â­Mesoamericans began writing during the mid-Pre-classic period. The Mayans were the first to keep any sort of historical record, and the beginnings of the calendar were born. The Mayans used stelae, or stone monuments, to carve their civil events, calendars and astronomy knowledge. They also inscribed their religious beliefs and mythology on pottery.
The nucleus is a membrane bound structure that contains the cell's hereditary information and controls the cell's growth and reproduction. It is commonly the most prominent organelle in the cell. The nucleus is surrounded by a structure called the nuclear envelope.
Animal Cell Structure Animal cells are typical of the eukaryotic cell, enclosed by a plasma membrane and containing a membrane-bound nucleus and organelles. Unlike the eukaryotic cells of plants and fungi, animal cells do not have a cell wall.This feature was lost in the distant past by the single-celled organisms that gave rise to the kingdom Animalia.nimal Cell Structure Animal cells are typical of the eukaryotic cell, enclosed by a plasma membrane and containing a membrane-bound nucleus and organelles. Unlike the eukaryotic cells of plants and fungi, animal cells do not have a cell wall.