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3.2 Cell Membrane
Cells
| Question | Answer |
|---|---|
| Cell Membrane Structure | encloses the contents of the cell: regulates & allows only certain substances through the cell membrane & the integral proteins |
| Fluid Mosaic | moves laterally, like a ping-pong ball in water |
| Phospholipid Bilayer | cell membrane: a double layer of phospholipid molecules |
| Integral (carrier) Proteins | act as gates or channels to transport molecules through the membrane |
| Peripheral Proteins | act as recognizers, receptors or cell joiners |
| Diffusion | PASSIVE transport- NO energy because from high to low concentration; Random movement of molecules from high to low concentrations with NO additional energy |
| Osmosis | PASSIVE transport of WATER- NO energy because from high to low concentration; diffusion of water into or out of cell; from an area of high water concentration to low (with the gradient); water moves to the most solutes |
| Osmotic Pressure | force excerted on membrane due to movement of H2O |
| Hypertonic Solutions | solution is high in solutes, causes cell to shrink |
| Hypotonic Solution | solution is low in solutes, causes cell to swell |
| Isotonic | dissolved particles outside the cell are equal to the concentration of dissolved particles in inside the cell; continued movement of molecules |
| Filtration | passage of fluid through a membrane through mechanical pressure |
| Facilitated transport/diffusion | PASSIVE transport- NO energy because from high to low concentration; with gradient |
| Active transport | needs additional energy; ATP |
| Active transport | uses energy from ATP to pass from low to against gradient; from low to high concentration with the help of a carrier protein & ATP |
| Sodium Potassium (Na+ K+)Pump | ACTIVE transport: is carrier protein that pushes Na+ K+ into & out of the cell (against their gradient) for muscles and nerves |
| Endocytosis (phagocytosis) | ACTIVE transport: needs ATP; plasma membrane envelopes a substance (that is too large for a carrier protein or not lipid soluable) fuses to the outside of the cell, pinches off to form a vesicle and it is released inside the cell |
| Exocytosis | ACTIVE transport: needs ATP; a vesicle fuses to the inside of the plasma membrane and is released to the outside of the cell |
| Diffusion examples | gases: CO2 & O2 and alcohols |
| Facilitated transport/diffusion: Why use carrier protein instead of going through the membrane? | most solutes are not lipid soluable & must be transported (allowed) across the membrane with the help of a carrier protein (channel) |
| Facilitated transport/diffusion examples: | amino acids & glucose |