the plasma membrane
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The Plasma Membrane. Maintaining Homeostasis. Cell Membrane - Multiple names - plasma membrane, phospholipid bilayer , lipid bilayer , biological membrane -Controls what comes into the cell and what goes out, it is said to be selectively permeable - PowerPoint PPT PresentationTRANSCRIPT
The Plasma Membrane
Maintaining Homeostasis
Cell Membrane- Multiple names - plasma membrane, phospholipid
bilayer, lipid bilayer , biological membrane-Controls what comes into the cell and what goes out, it is
said to be selectively permeable-cell membrane is fluid, pieces move around feely
this is called the fluid-mosaic model- Contains proteins
* Transport (Channel and Carrier)* Adhesion* Recognition (Antigens)* Receptor Sites
- Contains cholesterol to keep fluid
Tile Mosaic
Biological Membranes and Maintenance of Homeostasis
Components to the Plasma Membrane
Phospholipids –Two layers, that float over one another
Chanel Proteins –allow large molecule to move into and out of the cell
Receptor Proteins – used to identify the cell type, and allows for cell to cell communication, through the use of hormones etc
Maintaining Homeostasis- Passive Transport Osmosis and Diffusion
Passive Transport- the unassisted movement of materials across the cell membrane that does not require energy, only for small molecules
Diffusion – the movement of materials down a concentration gradient from high concentrations to lower concentrations
Osmosis- special type of diffusion, that only refers to water moving down a concentration gradient from high to low concentrations
Large molecules are trapped inside the cell, but water can move freely into and out of the cell
For a cell to be happy or to be in equilibrium, the cell needs the same concentration of water on the inside of the cell as the outside of the cell
Solutions – homogeneous mixture of two or more substancesSolvent – the stuff the does the dissolving ( Ex: Water)Solute- the stuff that is being dissolved ( Ex: Salt)
Osmosis Animation
Types of Solutions - Hypertonic
More water inside the cell then outside the cell
Water moves out of the cell cause the cell to shrink ( crenate)
Types of Solutions - Hypotonic
Hypo = Hippo
More water outside the cell then inside
Water moves into the cell causes it to swell
Types of Solutions - Isotonic
Same amount water inside the cell as outside
No net movement of water, water moves in and water moves out but they balance each other out
Maintaining Homeostasis- Passive Transport
Facilitated Diffusion
Facilitated Diffusion-the assisted movement of material across the cell membrane through the use of channel (membrane) proteins
-requires no energy
Maintaining Homeostasis- Active Transport
Active Transport – the assisted movement of larger molecules across the cell membrane, through channel proteins. Molecules move up the concentration gradient from low concentrations to higher concentrations, thus the process requires energy
EX: Sodium-Potassium Pump is required for proper nerve functioning
Interactive –w/ Sodium potassium pump
Just Passing Through
How Osmosis works
Cell Transport - Endo/ Exocytosis
Process used by cells to import or export large molecules into and out of the cell
Phagocytosis ( Cell Eating)- large objects, used to get rid of pathogens and to absorb large molecules
Pinocytosis ( Cell Drinking)- used so the cell can obtain solute and single molecules such as a protein