Animal Cell. The Animal cell is surrounded by a semi-permeable cell membrane. The cell membrane allows only specific materials to move in and out of the cell. The different parts of the cell are called organelles. Nucleus, Mitochondria, Endoplasmic Reticulum, Golgi Apparatus, Lysosomes. The cytoplasm is a jelly like substance. Cytoplasm provides a surface for all the organelles in the animal cell. Nucleus being the control center of cell decides and controls most of the functions going on in the cell. Mitochondria are the sites for cellular respiration in cells. They are the powerhouses of the cell because they release energy rich compounds called ATP. ATP is needed for the functioning, growth and maintenance of the body. Let us now study about the endoplasmic reticulum. The endoplasmic reticulum is a large network of membrane bound sheets. They help in transporting and exchanging materials between the various regions of the cytoplasm. The endoplasmic reticulum is of two types: The smooth endoplasmic reticulum The rough endoplasmic reticulum. The smooth endoplasmic reticulum helps in the formation of lipids. Lipids are essential components of the cell membrane. The rough endoplasmic reticulum has ribosomes. Ribosomes help in building proteins in the rough endoplasmic reticulum. The protein is processed inside the golgi apparatus. The proteins are packaged and sent outside. The golgi apparatus is involved in the formation of lysosomes. The lysosomes contain powerful digestive enzymes that help in cell digestion. When the cell is damaged, the lysosome bursts. After the lysosome bursts, digestive enzymes get released. The digestive enzymes digest their own cell. Hence, lysosomes are called suicide bags of the cell.