Główna zawartość
The cell membrane review
Kluczowe pojęcia
Term | Meaning |
---|---|
Cell membrane | Specialized structure that surrounds the cell and its internal environment; controls movement of substances into/out of cell |
Hydrophobic | Molecule that repels water (“water-fearing”) |
Hydrophilic | Molecule that is attracted to water (“water-loving”) |
Amphipathic | Molecule that contains both a hydrophobic and a hydrophilic end |
Phospholipid | Amphipathic lipid made of glycerol, two fatty acid tails, and a phosphate group |
Phospholipid bilayer | A biological membrane involving two layers of phospholipids with their tails pointing inward |
Semipermeable membrane | Membrane that allows certain substances to pass through |
Structure and function of the cell membrane
The cell membrane is semipermeable (or selectively permeable).
It is made of a phospholipid bilayer, along with other various lipids, proteins, and carbohydrates.
Each phospholipid is amphipathic, with two hydrophobic tails and a hydrophilic head. The hydrophobic tails face inward towards one another, and the hydrophilic heads face outwards.
The unique structure of the cell membrane allows small substances (like oxygen or carbon dioxide) to easily pass through.
Często spotykane błędy i nieporozumienia
- Hydrophobic tails face inward and hydrophilic heads face outward. If you get these two ends mixed up, think of the root word “phobia” which means “fear.” Hydrophobic tails fear the water, so they will always try to be as far as possible from the water solutions in and out of the cell.
- The cell membrane contains a phospholipid bilayer, but the terms are not interchangeable. Part of the cell membrane is a phospholipid bilayer, made of two layers of phospholipid molecules. However, the cell membrane also contains other macromolecules like membrane proteins, and carbohydrates. Therefore, we can say that the cell membrane is made of a phospholipid bilayer, but it is not only made of it.
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