TEK B.4B Concept: Investigate and Identify Processes Including Transportation of Molecules 11/24/2018

The cell membrane is designed as a lipid bilayer with channel proteins or carrier proteins embedded within it. Transport proteins or channel proteins form channels that allow specific molecules to flow through the cell membrane. In facilitated diffusions, the movement is with the concentration gradient, moving from higher concentration to lower concentration, and requires no energy. A different type of protein embedded in the lipid bilayer are carrier proteins. These carrier proteins change shape and bind with specific molecules to assist with transportations across the cell membrane. When molecules are transported with the concentration gradient, the movement is another form of facilitated diffusion and requires no energy. When carrier proteins assist in cell transport by moving molecules against the concentration gradient, from lower concentration, the cell requires energy. This movement is called active transport. 11/24/2018

11/24/2018