The Cell Membrane 12/9/14

What do you know about the cell membrane already? Do-Now 12/17/14 What do you know about the cell membrane already?

What are the two main parts of a cell membrane?

The Cell Membrane Is made up of mostly proteins and lipids (fats)

Phospholipid Polar molecules have a charge

Lipid Bilayer

Phospholipid Bilayer The tails are The circular heads are hydrophobic (water-fearing). They HATE water. The tails are nonpolar (no charge) The circular heads are hydrophilic (water-loving) Polar (having a + or – charge) Polar likes polar, nonpolar likes nonpolar

Polar vs. Nonpolar

Cell membrane

Cell Membrane How are the hydrophilic heads oriented? Always face the water

Protein Components of the Cell membrane Some molecules cannot simply move through the membrane. They need help from…PROTEINS

Blue Biology Text book Page 220- 221(Read “ Membranes”) 1. What can pass through the bilayer with ease? 2. Why can’t glucose and other sugars pass through the membrane? 3. Can ions pass through the membrane? 4. What do hormones do once they bind to a receptor?

Molecular Transport Small, nonpolar molecules, water, and fat soluble molecules have no problem moving in & out of the cell through the phospholipids. Larger, polar molecules, glucose, and ions need to move through a protein.

Protein Receptors

Fluid Cell Membranes Note: membranes are fluid- the phospholipids and other parts of the membrane are constantly in motion- watch video. Also watch how molecules bind to protein receptors https://www.youtube.com/watch?v=GW0lqf4F qpg

Video http://www.youtube.com/watch?v=S7CJ7xZOj m0

Green text book Page 224 1,2,12,13,14,22,24 Page 206 1-4 Refer to pages 201-206 to find the answers

Cell Membrane Model Materials per pair: Bundle of cotton swabs (Note- you may use extra cotton swabs if needed) Rubber band 2 pipe cleaners of different colors 1 straw- cut the straw in half if it is not already done so. You should have 2 pieces of a straw. You are to make a model of the cell membrane using your materials. Each material will represent a different part of the membrane. Your model can be 2 dimensional or 3 dimensional depending on how you want to use your materials.

Questions for Cell Membrane Model 1. Draw a picture of your model. What does the straw represent in your model? What do the cotton swabs represent? What do the pipe cleaners represent? 2. How do the cotton swabs represent the polar and nonpolar characteristics of the cell membrane? Which part of the cotton swab is hydrophobic and which part is hydrophilic? 3. In your model, can the cotton swabs and proteins move around each other? In other words, is your model “fluid”? Explain whether your model is an accurate representation of real cell membranes.

Review of Membranes and Transport Stop at 9 minutes