Roles of Membranes
- Created by: Freja
- Created on: 13-04-21 10:00
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- Roles of Membranes
- Within Cells
- Compartmentalisation- dividing organelles into compartments, crating barriers, making their functions more efficient.
- Form vesicles to transport substances between different areas of the cell.
- They control which substances enter and leave the organelle, as they are partially permeable.
- Form lysosomes, which are digestive enzymes and so need to be separate.
- Membranes within organelles creating barriers between the membrane contents and the rest of the organelle.
- Membranes increase the surface area, which can be the site of chemical reactions.
- Membranes allow the DNA and nucleus to be separate from the rest of the cell.
- At the Surface of Cells
- Controls which substances can enter and leave the cell, as it is partially permeable only some molecules are let through the membrane.
- Allow recognition by other cells e.g. cells of the immune system.
- Membranes separate the cell from its environment .
- Membranes allow cell signalling (cell communica-tion), which is the communi-cation between cells to trigger a response.
- The release of a signal molecule by exocytosis. Glycolipids and glycoproteins are receptors for signals. The receptor is specific, and the shape of the signal and receptor are comple-mentary. The attachment of the signal molecule causes a change, and the cell surface membrane allows the entry of some signal molecules.
- Has a part in facilitated diffusion and active transport.
- Membrane Recptors
- Cell Communi-cation
- Cells need to communicate with each other to control processes inside the body and to respond to changes in the environment.
- Cells communicate using messenger molecules.
- 1) One cell releases a messenger molecules (e.g. a hormone) 2) This molecule travels (e.g. in the blood) to another cell 3) The messenger molecule is detected by the cell as it binds to a receptor on its cell membrane.
- Cell Signalling
- 1) Proteins in the cell membrane act as receptors for messenger molecules. These are called 'membrane-bound receptors' 2) Receptor proteins have specific shapes- only messenger molecules with a complemen-tary shape can bind to them.
- 3) Different cells have different types of receptors- they respond to different messenger molecules 4) A cell that responds to a particular messenger molecule is called a target cell.
- e.g. Glucagon is a hormone that's released when there isn't enough glucose in the blood. It binds to receptors on liver cells, causing the liver cells to break down stores of glycogen to glucose.
- Cell Communi-cation
- Within Cells
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