How do cells take in food when they don’t have hands?
Diffusion Free + zombie walk First of all, materials must be able to go in and out of the cell. In your opinion, what should go in? What should come out?
Diffusion Diffusion is powered by the difference in CONCENTRATION. Concentration: Amount of substance in a given amount of space. Substances always travel from… High concentration Low concentration
Outside the cell Inside the cell HIGH concentration LOW concentration Membrane Outside the cell Inside the cell HIGH concentration LOW concentration Food particles (sugar) Food particles (sugar) LOW concentration HIGH concentration Waste (ammonia, CO2) Waste (ammonia, CO2)
Diffusion So, does this mean that ANYTHING can come inside the cell as long as it is in higher concentration outside? Can you list some substances that the cell may not want to take in no matter what?
Outside the cell Inside the cell Good molecule Bad molecule Not all molecules can freely enter the cell. This is called selective permeability. Can cells reject every kind of bad molecules?
Osmosis Just as molecules can travel by diffusion, water molecules can travel by diffusion too This is called osmosis. High Water concentration Low Water concentration
Osmosis Activity (With gummy bears!) Let’s predict! What’s going to happen if we put the gummy bear in a water bath?
Today’s homework is… Workbook Section 1.3