AGENDA – 10/6/15 Take out science journal and outline from yesterday! Bell-Ringer: Sugar and Starch vs. Membrane Osmosis Notes Double Bubble/Venn Diagram – Active vs. Passive Transport

Membrane This test tube with water, dissolved sugar (X), and dissolved starch ( ● ) was placed in this cup of water. There is a membrane placed over the end of the test tube. 1.What is happening to the sugar? 2.What is happening to the starch? 3.This is a selective membrane. What do you THINK that means? BELL-RINGER : 10/6/15

Concentration and Diffusion

Section 8.1 Summary – pages In a cell, water always moves across the membrane toward a higher concentration of materials in order to dilute it…or lessen the concentration. The movement of water across a selectively permeable membrane is called osmosis.

Section 8.1 Summary – pages During osmosis, water diffuses across a selectively permeable membrane to even out CONCENTRATION of dissolved particles. Selectively permeable membrane What do you notice about the amount of dissolved material (concentration of red dots) on each side? A cell always works to make the concentration of dissolved material EQUAL on both sides of the membrane. Decide with your neighbor which way the water would need to flow in order for that to happen?

Section 8.1 Summary – pages Notice the number of dissolved molecules did not change on each side, but the amount of water changed. The CONCENTRATION on both sides is now more equal

Section 8.1 Summary – pages OSMOSIS WATER WILL ALWAYS MOVE TOWARD THE SIDE WITH THE HIGHER CONCENTRATION OF PARTICLES (In order to dilute it- or make it less concentrated)

Section 8.1 Summary – pages Most cells whether in multi-cellular or uni-cellular organisms, are subject to osmosis because they are surrounded by water solutions. H2OH2O H2OH2O Water Molecule Dissolved Molecule OSMOSIS

Section 8.1 Summary – pages An isotonic solution has the same concentration of dissolved substances in the solution as the concentration of dissolved substances inside the cell. So when a cell is an in isotonic solution, the concentration is equal inside and outside the cell. Water Molecule Dissolved Molecule ISOTONIC Isotonic solution = same concentration inside and outside the cell

Section 8.1 Summary – pages This plant cell has its normal shape and pressure in an isotonic solution. ISOTONIC This is an animal blood cell in an isotonic solution. Water moves in and out at an equal rate

Section 8.1 Summary – pages HYPOTONIC If a cell is placed in a hypotonic solution, the concentration of dissolved substances is lower in the solution than the concentration inside the cell. Hypotonic solution = Low concentration solution

Section 8.1 Summary – pages Plant cells swell beyond their normal size as pressure increases. HYPOTONIC Since animal cells don’t have a hard cell wall like plants, they could burst if too much water enters

Section 8.1 Summary – pages If a cell is placed in a hypertonic solution, the concentration of dissolved particles in the solution is higher than inside the cell. HYPERTONIC Hypertonic solution = Higher concentration solution

Section 8.1 Summary – pages Plant cells lose pressure as the plasma membrane shrinks away from the cell wall. HYPERTONIC Animal cells shrink up like raisins.

In Isotonic solutionIn Hypotonic solutionIn Hypertonic solution DISCUSS WITH YOUR NEIGHBOR HOW EACH SOLUTION AFFECTS CELLS.

Section 8.1 Summary – pages When a cell uses no energy to move particles across the plasma membrane it is called passive transport. Plasma membrane PASSIVE TRANSPORT Water molecules can pass through the plasma membrane by simple diffusion. The cell uses no energy to move these particles

Section 8.1 Summary – pages Passive transport of materials across the membrane using transport proteins is called facilitated diffusion. Plasma Membrane Concentration gradient PASSIVE TRANSPORT Remember that there are transport proteins found in the plasma membrane. Facilitated means “to be helped” The proteins help the molecules across

Section 8.1 Summary – pages Movement of materials through a membrane AGAINST the concentration gradient (going against the flow) is called active transport because it REQUIRES ENERGY from the cell. Plasma membrane Concentration gradient Carrier proteins Cellular energy Step 1Step 2 ACTIVE TRANSPORT

DISCUSS WITH YOUR NEIGHBOR THE DIFFERENT TYPES OF TRANSPORT SHOWN. Simple

Section 8.1 Summary – pages Some cells can take in large molecules, groups of molecules, or even whole cells. STUFF THAT’S WAY TOO BIG TO GO THROUGH THE PLASMA MEMBRANE. TRANSPORT of LARGE MOLECULES

Section 8.1 Summary – pages Endo-cytosis is a process by which a cell surrounds and takes material INTO the CYTOPLASM. TRANSPORT of LARGE MOLECULES

Section 8.1 Summary – pages TRANSPORT of LARGE MOLECULES The material is engulfed and enclosed by a portion of the cell’s plasma membrane.

Section 8.1 Summary – pages Exocytosis is the expulsion or secretion of large or a bulk of materials from a cell. TRANSPORT of LARGE MOLECULES Inside the cellOutside the cell

Section 8.1 Summary – pages Exocytosis Digestion TRANSPORT of LARGE MOLECULES Endocytosis Endocytosis and exocytosis both move masses of material and both require energy, and therefore are types of active transport