PROTEIN!!!!!!!!!!!!!!!!!!!!!!!!!
The structures that allow certain materials to pass through the cell membrane are Proteins. Some such Proteins are known as Channel Proteins, Carrier Proteins, Sodium-Potassium pumps, and Proton pumps just to name a few.
Membrane transporter.
protein
The membrane
membrane
These special structures are called protein gates or protein channels. Water is able to diffuse through the cell membrane since it is a small molecule. However, there are channels called aquaporins that allow water to enter the cell. A glucose molecule cannot just diffuse into a cell. There are glucose channels on the surface of the cell membrane that bind glucose molecules and allow them to enter the cell.
diffusion and osmosis
carrier proteins
Membrane transporter.
PROTEIN!!!!!!!!!!!!!!!!!!!!!!!!!
membrane proteins act as carriers or channels for the specific movement of various substances in to and out of the cells.
PROTEIN!!!!!!!!!!!!!!!!!!!!!!!!!
proteins
proteins
What you are considering when you are referring to how easily materials can pass through a membrane is how permeable the cell wall or membrane is.
PROTEIN!!!!!!!!!!!!!!!!!!!!!!!!!
Through proteins in the membrane.
It is called semi-permeability, a series of biochemical structures and processes that Control The Ingress and Egress of bio-materials into and out of The Cell.
The membrane
The cells go through the cell's membrane