Table of Contents
What membrane only allows certain substances to pass through it?
The cell membrane is selectively permeable, allowing only a limited number of materials to diffuse through its lipid bilayer.
What is called endocytosis?
Endocytosis is a general term describing a process by which cells absorb external material by engulfing it with the cell membrane. Endocytosis is usually subdivided into pinocytosis and phagocytosis.
What molecules are involved in endocytosis?
The major route for endocytosis in most cells, and the best-understood, is that mediated by the molecule clathrin. This large protein assists in the formation of a coated pit on the inner surface of the plasma membrane of the cell. This pit then buds into the cell to form a coated vesicle in the cytoplasm of the cell.
What is the movement of molecules across the cell membrane called?
If the substances can move across the cell membrane without the cell expending energy, the movement of molecules is called passive transport. Consider substances that can easily diffuse through the lipid bilayer of the cell membrane, such as the gases oxygen (O 2) and carbon dioxide (CO 2).
What causes molecules to pass through the plasma membrane?
Figure 3.1.3 – Simple Diffusion Across the Cell (Plasma) Membrane: The structure of the lipid bilayer allows small, uncharged substances such as oxygen and carbon dioxide, and hydrophobic molecules such as lipids, to pass through the cell membrane, down their concentration gradient, by simple diffusion.
What makes up the membrane of a multicellular organism?
Despite differences in structure and function, all living cells in multicellular organisms have a surrounding cell membrane. As the outer layer of your skin separates your body from its environment, the cell membrane (also known as the plasma membrane) separates the inner contents of a cell from its exterior environment.
Which is the process of bringing material into the cell?
Endocytosis (bringing “into the cell”) is the process of a cell ingesting material by enveloping it in a portion of its cell membrane, and then pinching off that portion of membrane (Figure 9). Once pinched off, the portion of membrane and its contents becomes an independent, intracellular vesicle.