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The Plasma/Cell Membrane

The Plasma/Cell Membrane. Objective. Recognize the importance of semi-permeable membranes in regulating diffusion and maintaining homeostasis. The Cell Membrane. http://www.nature.com/scitable/content/ne0000/ne0000/ne0000/ne0000/14704938/SelectiveTransport_ksm_2_1.jpg.

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The Plasma/Cell Membrane

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  1. The Plasma/Cell Membrane

  2. Objective • Recognize the importance of semi-permeable membranes in regulating diffusion and maintaining homeostasis.

  3. The Cell Membrane http://www.nature.com/scitable/content/ne0000/ne0000/ne0000/ne0000/14704938/SelectiveTransport_ksm_2_1.jpg • The “cell membrane” is also known as “the plasma membrane.” • To survive, ALL living things must maintain a balance regardless of internal and external conditions.

  4. The plasma membrane is the boundary between the cell and its environment. • It allows a steady supply of glucose, amino acids, and lipids to enter the cell no matter what the external (outside) conditions are. • Remove excess amounts of nutrients when levels are too high. • Allow wastes and other products to leave the cell

  5. Homeostasis http://www.anselm.edu/homepage/jpitocch/genbio/homeostasis.JPG • The plasma membrane helps maintain homeostasis, which is the process of maintaining the cells internal (inside) environment

  6. Selective Permeability http://apbrwww5.apsu.edu/thompsonj/Anatomy%20&%20Physiology/2010/2010%20Exam%20Reviews/Exam%201%20Review/osmotic_pressure.jpg • The cell membrane is selectively permeable. • Is a process used to maintain homeostasis in which the plasma membrane allows some molecules in the cell while keeping others out.

  7. “Selective” “Permeable” • Selective – able to regulate which particles enter and leave (it’s choosey) • Permeable – allows particles to pass through • *another way to say selectively permeable is “semi-permeable”

  8. http://upload.wikimedia.org/wikipedia/commons/thumb/2/2a/Semipermeable_membrane.png/250px-Semipermeable_membrane.pnghttp://upload.wikimedia.org/wikipedia/commons/thumb/2/2a/Semipermeable_membrane.png/250px-Semipermeable_membrane.png • Why is the orange membrane considered semi-permeable? • What particles can’t get through the pores (holes) in the membrane?

  9. Structure of the Membrane • The plasma membrane is composed of TWO layers of phospholipids back to back

  10. The phospholipid bilayer is made up of: • A Hydrophilic head that is attracted to water • A Hydrophobic tail that is NOT attracted to water (scared of water).

  11. The cell’s environment is mostly water. It is the most abundant material inside a cell as well.

  12. “Fluid” Mosaic Model • The plasma membrane is described as being a flexible boundary of a cell. The phospholipids move within the membrane.

  13. Other Components: Cholesterol http://www.cytochemistry.net/cell-biology/cholesterol.jpg • Cholesterol plays an important role of preventing the fatty acid chains of the phospholipids from sticking together.

  14. Other Components: Transport Proteins • Allow substances or water materials to move across through plasma membrane. http://www.one-school.net/Malaysia/UniversityandCollege/SPM/revisioncard/biology/movementacrossmembrane/images/facilitateddiffusion.png

  15. Other Components: Receptor Proteins http://fwcdscience.wikispaces.com/file/view/transduction.gif/43381569/transduction.gif • The surface of the membrane bind to chemical messengers to allow certain substances to pass through the plasma membrane.

  16. Passive Transport versus Active Transport Energy REQUIRED NO energy required

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