Chapter 2 Lesson 3 Moving Cellular Materials

Cell Membrane The cell membrane is selectively permeable ◦ It allows certain things into the cell while keeping others out ◦ Another term is semi- permeable ◦ The chemical properties and physical properties determine if it can enter the cell  Physical- the size of the particle

Passive Transport The movement of substances into or out of the cell without using energy ◦ Small molecules- like Carbon dioxide or ◦ Oxygen ◦ Depends on the amount of the substance on each side of the membrane

Passive Transport Diffusion Osmosis Facilitated Diffusion

Diffusion The movement of a substance from a higher concentration to a lower concentration Diffusion will continue until equilibrium- equal amounts of the substance on both sides of the membrane

Osmosis Special kind of diffusion Diffusion of water through a semi-permeable membrane Osmosis continues until equilibrium is reached Solute- the material dissolved ( sugar) Solvent- the solution or liquid (water)

Facilitated Diffusion Some molecules are too large or chemically unable to pass through the membrane Some molecules move with special helper proteins called transport proteins 2 types of proteins ◦ Carrier- carry things like glucose or sugar molecules ◦ Channel- carry things like sodium or potassium ions

Facilitated Diffusion

Active Transport Movement of substances through a cell membrane using energy Goes against the concentration gradient Low concentration to high concentration

Endocytosis and Exocytosis Some substances need to enter the cell but they are too large to do so. Endocytosis-  To enter the cell- the cell surrounds the substance with a membrane Exocytosis-  A cells vesicle release their contents outside the cell

Endocytosis

Exocytosis