Cell Membrane: Transport Diffusion SC.912.L.14.2 Relate structure to function for the components of plant and animal cells. Explain the role of cell membranes as a highly selective barrier (passive and active transport)

Cell Membrane Objective: explain how materials pass through a semipermeable membrane EQ: How do materials pass through the cell membrane?

Cell Membrane Structure: Function: Phospholipid bilayer that contains channel protein, cholesterol, and carbohydrate chains Provide a protective barrier around the cell Control what enters and exits the cell; semi-permeable like security

Suggestions? What did they use for: Phospholipid? Cholesterol? Protein Channel?

Suggestions? What did they use for? Phospholipids? Cholesterol? Protein Channel?

Suggestions? What did they use for: Phospholipid? Cholesterol? Channel Protein?

Making Observations On the LEFT side of your notebook, make some observations about the beaker of Iodine and starch filled “cell” When Iodine and starch mix, the solution will turn purple. Predict: what do you think will happen when we place the “cell” into the beaker of Iodine?

Review: the Membrane What molecules are able to easily pass from one side of the membrane to the other? Why? Some materials (small, nonpolar) can move across the membrane without help; some (usually larger, polar molecules) use the channels made by proteins to move across the membrane

Active Transport drives molecules against the concentration gradient from areas of low concentration to regions of HIGH concentration Transport proteins in the membrane use chemical energy (ATP) to move molecules across the membrane

Types of Active Transport: Protein pumps: Smaller molecules go through protein channels and require ATP vesicles transport = larger materials move across the cell membrane through vesicles This requires an input of energy

Recall: When we discussed energy in reactions, we used the terms “endothermic” and “exothermic” – what did the prefixes “endo” and “exo” mean? Endo = into; coming in; absorbed Exo = out of; released; leaving (exiting)

Active Transport via Vesicles Endocytosis: Exocytosis: the RELEASE of substances OUT of a cell using energy A vesicle forms around materials inside the cell The vesicle fuses to the cell membrane The contents of the vesicle are released out of the cell process of taking large molecules or liquids INTO a cell using energy The cell membrane pinches in, making a pocket/vesicle for the substance The pocket pinches off inside the cell The membrane of the vesicle is broken down by enzymes (ex. from lysosomes) inside the cell to release the materials

Active= ATP (energy) Endoccytosis Vesicle transport Active Exocytosis (low to high) Vesicle transport Endoccytosis Exocytosis Protein Pump

Passive Transport molecules can move across the cell membrane from HIGH concentration to low concentration No energy is required

Passive Transport: Diffusion molecules move from a region of high concentration to a region of low concentration Movement is DOWN a Concentration Gradient Does not require energy because it is passive transport Molecules move through phospholipid bilayer

Passive Transport: Diffusion Osmosis Facilitated Diffusion still requires NO energy moves high to low but through protein channels Movement of water across the membrane from high to low concentration No energy required

Check for Understanding Based on what we’ve learned about diffusion, predict the direction that the molecules will move: Outside Inside

Check for Understanding Based on what we’ve learned about diffusion, predict the direction that the molecules will move: Outside Inside

Check for Understanding Based on what we’ve learned about diffusion, predict the direction that the molecules will move: Outside Inside

Check for Understanding Based on what we’ve learned about diffusion, predict the direction that the molecules will move: Outside Inside

Check for Understanding Based on what we’ve learned about diffusion, predict the direction that the molecules will move: Outside Inside

Check for Understanding Based on what we’ve learned about diffusion, predict the direction that the molecules will move: Outside Inside NO NET MOVEMENT: the molecules go in both directions

Diffusion Our “cell” (ziplock with starch solution) will be placed in the iodine solution and allowed to sit. When iodine and starch mix, the solution turns purple. PREDICT: what do you expect will happen?

Diffusion lab After being allowed to sit, the “cell” is removed from the solution and ….. The starch solution has turned purple. The iodine solution appears unchanged (notice that there is no cloudiness to the solution)

Diffusion Questions – left side Based on your results, which do you think is smaller: iodine molecules or starch molecules? How do you know? Based on the results of this investigation, rank the following by their relative size, from smallest to largest: water molecules, starch molecules, dialysis tubing pores, and iodine molecules What is the difference between diffusion (a type of passive transport) and active transport? Which is this experiment?

Active vs Passive Transport Using the grid, test which if the materials fits through on its own and which materials need an extra “push”. Record your findings in your activity sheet. Paste to page *** C- level 2 H- follow the activity instructions A- model active and passive transport M- remain seated at your pod P- collect data on student sheet and answer questions Success Ping pong ball Beans Rice Marble dice

Exit ticket Clear your desk!