I need an explanation please! I understand that endocytosis is when the cell takes in extracellular material and small internal vesicles called endosomes are formed. The endosomes are then sorted according to their contents,(by the golgi apparatus) to go to different cellular destinations like lysosomes. But, what i'm having trouble understanding is how the receptors fit in. My textbook says this: "Endocytosis is a selective process, controlled by receptors on the cell surface that recognise and bind chemical signals on extracellular molecules or particles." I don't get what it means by, bind chemical signals! Can someone please explain to me how the receptors are involved in endocytosis, any diagrams or pictures would also be useful because i find it easier to understand things if i can visualise them! Thanks in advance.