Cell membrane functions like a hydrophobic barrier around cell, so that water-soluble compounds and ions do not readily pass across; a similar membrane surrounds cell organelles. Thus, there is a need for transporters to regulate flow in and out of cells and cell organelles. The most important function of a membrane is to maintain a specific microenvironment inside of a cell, or a cell organelle, by controlling the entry and exit of molecules and inorganic ions. The cell is not just a ‘bag’ of various components, it is a highly organized collection of interacting compartments whose separation optimizes the efficiency.
Cell nucleus contains the most important portion of genetic material, and regulates all cell function. At gastrulation the nucleus begins to regulate the further cell development.
Mitochondria transform the chemical energy of metabolites in cytoplasm into energy that is easily accessible by the cell.
Protein synthetic machinery is centered on ribosomes, associated with the endoplasmic reticulum.
Lysosomes are sites of intracellular digestion and turnover of cellular components.