Transport Across Membranes

Transport Across Membranes Passive Transport Examples of Passive Transport Cells and Osmosis Active Transport Comparing Passive and Active Transport

Passive Transport Passive Transport: movement of molecules across a membrane from an area of high concentration to an area of low concentration. Passive Transport does not require energy. Three types: Diffusion Osmosis Facilitated Diffusion

Examples of Passive Transport 1) Diffusion: the movement of any particle from high to low concentration. Glue this picture beneath your definition, Label the areas of high and low concentration, then shade them two different colors.

Examples of Passive Transport 2) Osmosis: the movement of water from high to low concentration. Glue this picture beneath your definition, Label the areas of high and low concentration in each picture, then shade them two different colors.

Examples of Passive Transport 3) Facilitated Diffusion: movement of large molecules from high to low through transport proteins. Glue this picture beneath your definition, Label and shade the areas of high and low concentration, and the transport (carrier) proteins.

Cells and Osmosis Hypotonic—water moves into the cell High Low. Therefore cell swells. Isotonic—water moves in and out of cell because there is no concentration difference. Therefore cell does not change. Hypertonic—water moves out of cell High Low. Therefore cell shrivels.

Cells and Osmosis In animal cells, hypotonic conditions can lead to lysis, cells bursting. In plant cells, hypotonic conditions provide the water pressure needed to support the cell wall. In plant and animal cells, hypertonic conditions cause cells to shrivel (this is why plants wilt when not watered).

Active Transport Active transport: movement of molecules from an area of low concentration to an area of high concentration. Active transport uses membrane proteins that require energy (ATP). Glue down the picture, then label and shade: Areas of high & low concentration Membrane proteins ATP

Active Transport Endocytosis: uses lots of energy to move particles inside the cell. Exocytosis: uses lots of energy to move particles outside the cell. Endocytosis Exocytosis

Comparing Active & Passive Transport In the top portion of the flap, draw a Venn diagram. Label one circle Active Transport and the other Passive Transport. Place the words from the chart below into the appropriate places on the Venn diagram. Uses energy No energy required Osmosis Diffusion Semi-permeable membrane With a gradient High  Low Low  High Movement of particles Facilitated diffusion Exocytosis Membrane protein Against a gradient Endocytosis ATP

Comparing Active & Passive Transport High Active Transport Low to High Uses Energy Passive Transport High to Low No Energy Low