F Q How does the cell membrane maintain
F. Q. How does the cell membrane maintain homeostasis for the cell? Topic: The cell membrane
Think About It! �How is a window screen similar to a cell membrane? Answer the following questions to find out. . .
1. What are some things that can pass through a window screen? 2. What are some things that cannot pass through a window screen? Why is it important to keep these things from moving through the screen? 3. The cell is surrounded by a plasma membrane, which regulates what enters and leaves the cell. Why is it important to regulate what moves into and out of a cell?
Biology “Buzz”- The Cell Membrane FUNCTION The cell membrane has a number of functions: 1. Separates the cell from the surrounding environment. 2. Controls what goes into and out of the cell. The cell membrane is called selectively permeable or semi-permeable. 3. Communicates with the environment inside and outside of the cell. I.
II. Structure of cell membrane �Bilayer of lipids with embedded proteins. �Lipids are actually phospholipids Phosphate layer “likes” water because its polar. Lipid tails repel water. �Proteins are in various places along membrane: -Some are in outer surface -Some are in inner surface -Some are extended throughout the membrane.
• This model is called the fluid mosaic model because the membrane is very flexible and proteins are able to move within.
The proteins of the cell membrane have three main functions: 1. Transport proteins also Channel proteins. -Assist materials in and out of cell. 2. Marker proteins- the cells “nametags”. -They distinguish your cells from anyone else’s cells. 3. Receptor proteins- receives messages for the cell.
Q. What molecules can pass through the cell membrane? � Very small molecules such as carbon dioxide, oxygen and water. These materials move freely through lipid bilayer because of their small size. � Small molecules made of lipids or molecules that dissolve in lipids such as chloroform and alcohol pass through easily. WHY? � ANS. Alcohol and chloroform will simply dissolve through the cell membrane and into the cell because the cell membrane is made up of lipids.
�Ions such as sodium, potassium, and calcium can pass through but only through the protein channels. �Other small molecules such as glucose and amino acids that the cell needs will pass through but only through the protein channels with help.
That’s all for today folks! Now complete your Closing Thoughts!
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