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Why do <b>Phospholipids</b> form a double layer? |
Because they serve as the framework in which the other components of the membrane are embedded. |
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Explain how membrane <b>receptors</b> transmit messages across the <b>cell membrane.</b> |
Membrane receptors are activated when a certain chemical attaches itself to the receptor. The receptor opens up and allows certain ions in through it’s receptor channel into the cell (sodium, potassium, etc.) When an increased amount of sodium enters the cell, the cell depolarizes. |
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Describe the similarities between enzymes and receptors. |
Both enzymes and receptors have specific sites for the substrates. To bind the receptor causes a response beyond the cell membrane and the enzyme facilitates a chemical change in the substrate. |
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If proteins were rigid, why would they make poor receptors? |
If proteins were rigid, they would make poor receptors because the proteins has to have a certain shape and molecule to bond to. |
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Insulin helps cells take up sugar from the blood. Explain the effect on blood sugar levels if insulin receptors stopped working. |
Sugar would not be taken out of the blood because no signal would be going to the receptor=high blood sugar (diabetes) . |
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cell membrane |
A cell structure that controls which substances can enter or leave the cell. |
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phospholipid |
a lipid that contains phosphorus and that is a structural component in cell membranes |
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phospholipids are contained of… |
a charged phosphate group, glycerol, and two fatty acid chains |
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fluid mosaic model |
model that describes the arrangement and movement of the molecules that make up a cell membrane |
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selective permeability |
A property of a plasma membrane that allows some substances to cross more easily than others. |
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receptor |
protein that detects a signal molecule and performs an action in response |
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intracellular receptor |
receptors located inside the cell rather than on its cell membrane |
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membrane receptor |
A molecule that cannot cross the membrane may bind to a receptor in the cell membrane. |
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