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.
Nucleus. The nucleus is one of the most important organelles in a cell. It is often the largest organelle in animal cells, but this is not always the case. Nuclei contain the genetic material called DNA that is responsible for controlling and directing all cell activities.lthough some animal cells have this organelle, most of them are small. However, in plant cells, vacuoles are often very large and often take up much of the space in the cell. They hold water, food, or waste for the cells.