Movement In and Out of Cells Chapter 2 1. Diffusion 2. Osmosis 3. Active Transport

1. Diffusion The net movement of molecules from a region of their higher concentration to a region of their lower concentration along a concentration gradient, as a result of their random movement. When they can move freely, particles tend to spread themselves out as evenly as possible. Examples: Plant cells: Gas exchange Plant cells: Flowers Animal cells: Gas exchange Animal cells: Digestion Main Menu

Example: Plant Cell-Gas Exchange LC HC HC LC Carbon dioxide diffuses into the leaves through the stomata from a high concentration to a low concentration along the concentration gradient. Oxygen diffuses out of the leaves through the stomata from a high concentration to a low concentration along the concentration gradient. 1.

Example: Plant Cell-Flowers LC HC HC LC The scent from flowers diffuse from a high concentration to a low concentration along the concentration gradient into the air around them, which stimulate receptors in the bee’s body. 1.

Example: Animal Cell-Gas Exchange HC HC LC LC HC HC LC Oxygen diffuses into of the cell from a high concentration to a low concentration along the concentration gradient. Carbon dioxide diffuses out of the cell from a high concentration to a low concentration along the concentration gradient. 1.

Example: Animal Cell-Digestion HC LC LC LC Food diffuses out of the ileum (small intestine) during digestion from a high concentration to a low concentration along the concentration gradient. 1.

2. Osmosis The diffusion of water molecules from a region of their higher concentration (dilute solution) to a region of their lower concentration (concentrated solution), through a partially permeable membrane. The diffusion of water molecules from a region of their high water potential to a region of their low water potential, along the water potential gradient. Dilute Solution: high water potential: More solvent (water) Less solute (sugar/salt) Concentrated Solution: low water potential: Less solvent (water) More solute (sugar/salt) Main Menu Animal cell: Dilute solution Plant cell: Dilute solution Animal cell: Concentrated solution Plant cell: Concentrated solution

Osmosis in Animal Cells: Dilute solution Dilute solution: pure water: high concentration Concentrated solution: cytoplasm: low concentration More concentrated solution inside the cytoplasm Less concentrated solution in the pure water Water diffuses into the cell through the partially permeable cell surface membrane. Water diffuses from a high concentration (dilute solution: pure water) to a low concentration (concentrated solution: cytoplasm) along the concentration gradient through the partially permeable cell surface membrane 2.

Osmosis in Animal Cells: Concentrated solution Dilute solution: cytoplasm: high concentration Concentrated solution: outside cytoplasm: low concentration Water diffuses out of the cell through the partially permeable cell surface membrane. Water diffuses from a high concentration (dilute solution: cytoplasm) to a low concentration (concentrated solution: outside cytoplasm) along the concentration gradient through the partially permeable cell surface membrane 2.

Osmosis in Plant Cells: Dilute solution Dilute solution: pure water: high concentration Concentrated solution: cytoplasm: low concentration More concentrated solution inside the cytoplasm Less concentrated solution in the pure water Water diffuses into the cell through the partially permeable cell surface membrane. Water diffuses from a high concentration (dilute solution: pure water) to a low concentration (concentrated solution: cytoplasm) along the concentration gradient through the partially permeable cell surface membrane The cell swells and becomes turgid. 2.

Osmosis in Plant Cells: Concentrated solution Dilute solution: cytoplasm: high concentration Concentrated solution: outside cytoplasm: low concentration Water diffuses into the cell through the partially permeable cell surface membrane. Water diffuses from a high concentration (dilute solution: cytoplasm to a low concentration (concentrated solution: outside cytoplasm) along the concentration gradient through the partially permeable cell surface membrane The cell shrinks and becomes flaccid. The cell plasmolysis: the cell membrane detaches from the cell wall. 2.

3. Active Transport The movement of ions in or out of a cell through a cell membrane, from a region of their lower concentration o a region of their lower concentration against their concentration gradient, using energy released during respiration. Cell membranes contain carrier proteins Active Transport in Plants Active Transport in Animals Main Menu

Active Transport: Root hair cells Vacuole soil particles Cell membrane with cell wall Minerals and Water absorbed The movement of nitrate ions into a root hair cell through the cell membrane, from a region of their lower concentration to a region of their higher concentration against their concentration gradient, using energy released during respiration. 3.

Active Transport: Small intestine The movement of glucose into cells of villi through the cell membrane, from a region of their lower concentration to a region of their higher concentration against their concentration gradient, using energy released during respiration. 3.