5.1 Cell Membranes
- Created by: Billie2503
- Created on: 05-11-19 14:11
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Membrane function
- Membanes at the cell surface
- a barrier between the cell and its environment
- controls what enters and leaves
- partially permeable- let in some but not all molecules
- molecules move across by diffusion, osmosis or active transport
- cell signalling
- Membranes within cells
- compartmentalisation- act as a barrier between organelle and the cytoplasm [e.g. enzymes are kept together inside a mitochondion by its outer membrane
- membranes for vesicles to transport substances between different areas of the cell [e.g. proteins from the RER to the golgi during protein synthesis]
- partially permeable- controls what enters and leaves organelle [e.g. RNA leaves the nucleus- DNA is too big]
- membranes inside organelles- barriers between its contents and the rest of the organelle [e.g. thylakoid membranes in chloropasts keeps the components for photosynthesis together]
- site of chemical reactions- some are folded to increase surface area making the reactions more efficent [e.g. inner membrane of mitochondrion contains enzymes needed for respiration]
Membrane Structure
- composed of lipids, proteins and carbohydrates
- …
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