The Cell in Its Environment How do Materials Move Into and Out of Cells?

A Selective Barrier In what way is the cell membrane like a gatekeeper? The Cell in Its Environment

How Do Materials Move Into and Out of Cells? To live and function cells must let certain materials into and out of the cell Cell membrane consists of a double layer of lipid molecules lined up side by side Selectively permeable – some substances can move across the membrane and others cannot

Passive Transport The movement of dissolved materials across a cell membrane without using the cells energy

Diffusion A drop of food coloring in a plate of gelatin gradually spreads as molecules of the dye diffuse. How would the third plate look if diffusion continues?

Diffusion High concentration Low concentration EquilibriumOsmosis

Facilitated Diffusion Blocks and shapes color coded example Sugars do not cross easily through the membranes lipid molecules, so proteins in the cell membrane form channels through which the sugars can pass

Active Transport The movement of materials across a cell membrane using energy Low concentration to high concentration

Crossing the Cell Membrane Molecules move into and out of a cell by means of passive or active transport. Complete the boxes, and describe where the concentration of each substance is high or low.

Large Cell and Small Cell How does the difference in the size of cells affect their processes?

Moving Large Particles Endocytosis – sometimes the particle the cell needs ingest are too large to cross the cell membrane, the cell membrane then changes shape and engulfs the particle. Exocytosis – allows large particles to leave the cell

Water Molecule Imagine that the yellow line is the cell membrane. What is the overall direction in which water will travel as a result of osmosis?