Osmosis
Osmosis Not all things can move across a cell membrane. Permeable: substance can pass through a membrane Impermeable substance cannot pass through a membrane
Osmosis Selectively permeable membrane - some substance can pass through the membrane while others cannot. Osmosis: diffusion of water through a selectively permeable membrane.
Sugar Water & Selectively Permeable Membrane If you have a membrane impermeable to sugar, sugar cannot pass through If it is permeable to water, water can pass In a beaker, water will pass through the membrane until the concentration of sugar (g/L) is equal on both sides of the membrane.
Solution Concentrations Isotonic: 2 solutions with the same concentration Hypertonic: solution with higher concentration Hypotonic: solution with lower concentration
Fresh Water and Salt Water Fish
Osmosis in Cells
Osmotic Pressure pressure due to the movement of water in/out a cell
Facilitated Diffusion & Active Transport
Facilitated Diffusion Protein channels allow certain molecules to cross the cell membrane Red Blood Cells have channels that help glucose move in/out channel can only be used by glucose Substances move in response to concentration gradient high to low concentrations Doesn’t require energy
Active Transport Process to move molecules against the concentration gradient requires energy carried out by transport proteins or pumps Transporting Molecules small molecules and ions (Na, Ca, K) by energy-requiring pumps
Three Types of Transport
Endocytosis taking in material by enfolding, or pockets, of the cell membrane pockets break loose from the outer portion of the cell membrane forms a vacuole within the cytoplasm can take in larger molecules, clumps of food, or whole cells
Types of Endocytosis Pinocytosis: uptake of liquids tiny pockets along the cell membrane fill with liquid and form vacuoles within the cell Phagocytosis : “cell eating” Extension of the cytoplasm surround a particle and package it within a food vacuole
Exocytosis release of material membrane surrounding the vacuole fuses with the cell membrane, forcing the contents out of the cell