Cell biology Organelles Specialized structures within a cell that perform a specific function. Different cells contain different organelles, which allow the cell to carry out its required functions.  Cell membrane • Controls the EXIT and ENTRY of a cell  Let IN nutrients (sugars, amino acids, vitamins, fatty acid)  Let OUT wastes • Surface of the membrane contains chemicals that respond to messages outside the cell • Parts of the surface are sticky to keep contact with surrounding cells  Nucleus • Instructs the functioning of the cell (brain of the cell) • Holds genetic information of the cell in structures called CHROMOSOMES  Membrane has many pores (nuclear pores) which allows materials to pass through  Endoplasmic reticulum • May be SMOOTH or ROUGH  Rough appearance caused by the presence of ribosomes • (SMOOTH)  No ribosome  Manufacture hormones and lipids  Process toxins  Manage metabolism • (ROUGH)  Yes ribosome  Act as a transport system within the cell  The ribosomes synthesise proteins