Cell Membrane Review! Each table group will be assigned a different component of the cell membrane You need to introduce yourself, what you look like and what your role is (2-3 sentences) Get in place as a table group as a human “cell membrane” based on your assigned component

Bubble Demo 2.0 Activity #4 What does this tell you about the properties of the cell membrane? What kinds of answers did you get for the other activities? One person from each table group Skip the challenge section

Cell Transport… in a Nutshell Passive Transport Diffusion Osmosis Facilitated Diffusion Active Carrier Proteins Endocytosis Exocytosis

How do molecules get inside the cell? Directly through the phospholipid bilayer Oxygen, CO2, water Diffusion/osmosis Protein channels Charged ions like sodium, calcium, potassium or chlorine Diffusion and osmosis Carrier proteins Larger molecules like glucose and amino acids Facilitated diffusion

Passive Transport SBI3C – Ms. Q October 2nd 2018

On Your Own… Read p. 64-67 Make a Venn diagram with 2-3 points in each circle comparing osmosis, diffusion and facilitated diffusion Compare answers as a class

Passive Transport No cell energy needed Molecules enter or leave the cell one at a time Molecules move with the concentration gradient due to random molecular motion High to low Talk about kidney dialysis as an example – passes a patient’s blood through dialysis tubing (which allows some substances but not others to get through, making it semi-permeable), surrounded by a special solution so the stuff you don’t need leaves and the stuff you need stays in – diffusion

Passive Transport

Diffusion Even spreading of molecules from an area of high concentration to an area of low concentration across a semi-permeable membrane Concentration: amount of a substance in a given volume Move with the concentration gradient Ex: In the cell membrane, small uncharged molecules and lipid molecules can pass through Febreze or perfume or tea bag as an example Molecules are constantly in motion When there is no net change in the molecule movement, it’s reached equilibrium

What is a solution? Solutions are a mixture of: Solvent: the part that does the dissolving (ex. water) Solute: part that gets dissolved (eg. Sugar) The cell is constantly trying to maintain a balance between the ECF (extracellular fluid) and the ICF (intracellular fluid/cytoplasm) This creates homeostasis (balance)

Diffusion

Osmosis Diffusion of water molecules across a selectively permeable membrane Move with the concentration gradient

Osmosis Water moving from an area of low concentration of solute to an area of high concentration of solute (in order to dilute them) Water moves from where is more water to less water. Cells want to have equal concentrations on both sides of the membrane!

Solution Tonicity ISOTONIC [Solute] inside cell = [Solute] outside cell No net water movement occurs This means homeostasis is achieved

Solution Tonicity HYPERTONIC [Solute] greater outside cell Water moves out of cell, into extracellular fluid

Solution Tonicity HYPOTONIC [Solute] less outside cell Water moves into cell from extracellular fluid

Water flows from hypotonic to hypertonic

Application of Osmosis Store fresh vegetables in fresh water to keep them crisp Intravenous (IV) drips must be ISOTONIC to a patient’s blood otherwise red blood cells could gain or lose fluid Reverse osmosis can desalinate ocean water and make it drinkable Osmosis is why your fingers “prune” when you go swimming

This week Tomorrow: Egg Demo + Facilitated Diffusion Thursday: Dialysis Tubing Lab Friday: Active Transport