Describe the two methods of active transport

Endocytosis

Process by which the cell surrounds and takes particles into the cell

Exocytosis

Secretion of material out of the plasma membrane

Proteins in the Membrane. Active transport usually happens across the cell membrane ... They are positioned to cross the membrane so one part is on the inside of the cell and one part is on the outside. Only when they cross the bilayer are they able to move molecules and ions in and out of the cell.