Cellular Transport 7.4

Cellular Transport Molecules can move in and out of a cell by a few different mechanisms Passive transport Diffusion Osmosis Facilitated diffusion Active transport Endo/Exocytosis

Passive transport This type of cellular transport moves molecules in and out of the cell without any energy. There are different types of passive transport Diffusion Osmosis Facilitated diffusion

Passive transport Diffusion- the movement of particles from an area where there are many particles of a substance to an area where there are fewer particles of the substance. Moving from a high concentration to a low concentration Any molecule can diffuse

Passive transport Osmosis- this is the diffusion of water only. When water molecules move from an area of high concentration to an area of low concentration. Only water moves by osmosis

Passive Transport Facilitated diffusion- this type of diffusion occurs by proteins embedded in the cell membrane called transport proteins. This type of diffusion DOES NOT use energy Facilitated diffusion still moves with the concentration gradient Cells would use transport proteins if molecules are too big of hydrophilic to pass through the semipermeable membrane

Passive Transport Molecules move in an out of a cell based on what kind of solution it’s in. There are 3 types of solutions that cells can be in. Isotonic Hypertonic Hypotonic

Passive Transport Isotonic- this type of solution has equal parts of solute and solvent. In this type of solution, water continuously moves in and out of the cell. Hypertonic- this type of solution has more solutes (sugar, salt, etc.) outside of the cell than inside. In this type of solution, cells will shrivel because water will move out of the cell to work with the concentration gradient There would be a lower Concentration of solutes outside of the cell than inside

Passive Transport Hypotonic- in this type of solution, there is more water/ solvent than solute. In this type of solution, cells will burst because water moves into the cell to work with the concentration gradient. There would be a higher concentration of solutes inside the cell than out.

Active Transport Active transport- a type of transport that moves molecules in or out of a cell against the concentration gradient. This type of transport requires energy because it moves from a low concentration to a high concentration. ATP is the unit of energy required.

Transport of Large Particles When transporting large molecules, cells must use a different type of transport. Exocytosis- when large materials are expelled from the cell Endocytosis- when large materials are taken in to the cell

Key points for 7.4 The cell membrane is vital to the movement of materials in and out of the cell Passive transport does not require energy Active transport does require energy Osmosis only occurs with water molecules