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Cell Membranes - Coggle Diagram
Cell Membranes
Cell membrane
If a molecule is small, and has no charge, it can move through a cell membrane easily. Some examples are oxygen, and carbon dioxide.
If a molecule is large, like glucose, it will need a protein to get it across the membrane. If a molecule is charged, like Na+ ion (sodium), it will need a protein to get it across the membrane.
Cell membranes serve as barriers and gatekeepers. They are semi-permeable which means that some molecules can diffuse across the lipid bi-layer but others cannot.
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Carbohydrates are like identification badges. Cells that have different membrane carbohydrates do different jobs. The immune system uses the carbohydrates to recognize that your cells belong to you and are not viruses, bacteria, or other foreign cells.
The cell membrane is flexible like oil. This flexibility in the cell membrane allows the cell to change shape as needed, to grow and divide or to move in response to its environment.
Proteins
Aquaporins - However, cells also have a special protein called an aquaporin. This is a channel protein that is exclusively used to move water inside and outside of the cell.
Carrier proteins are used in active transport. Carrier proteins use energy to take things into the cell.
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letting molecules into and out of the cell so that the cell can maintain its internal environment and metabolize
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interacting with specific signals from the environment and transmitting these signals to the interior of the cell, again so the cell can sense and respond to its environment
Transport
passive - is simple diffusion it is where molecules go from high to low concentration with no effort and don't need proteins.
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facilitated - transport of molecules from high to low concentration using proteins like channel proteins.
Concentration gradient -
Molecules can move from a higher to a lower concentration gradient. In fact, all of the molecules mentioned above will move from a higher to a lower concentration, provided they have their proper transport protein (when required).
Active transport requires the input of ATP (energy) in order to transport the molecule, and this is because the molecule is being transported against the concentration gradient (from a lower to a higher concentration).
Diffusion
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facilitated diffusion - the passive movement of molecules along the concentration gradient requiring help of proteins
Phospholipid bi-layer
Made up of multiple phospholipids; a phosphate head these are hydrophilic and 2 fatty acid tails that are hydrophobic
Osmosis - osmosis is the diffusion of water across a membrane from an area of higher water concentration to an area of lower concentration.
Solutions
Hypotonic
Is where there is more solution on the inside of the cell than the outside of the cell so a bunch of water goes into the cell until the cell bursts or the cell maintains homeostasis.
Hypertonic
It is where there is more solution on the outside of the cell than the outside of the cell. So a bunch of water goes out of the cell and the cell shrinks
Isotonic
Is where there is an equal amount of solution outside and inside of the cell. So there is no net loss or gain