Membrane sructure and functrion
- Created by: Natasha Granville
- Created on: 03-01-18 13:13
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- Membranes
- Structure and function
- Phospholipid bilayer
- hydrophilic phosphate heads form the inner and outer surfaces of the membrane
- hydrophobic fatty acid tails are protected from the aqueous environment by the hydrophilic phosphate heads
- hydrophilic phosphate heads form the inner and outer surfaces of the membrane
- Glycolipids - lipids with attached carbohydrate chains
- cell-to-cell recognition
- glycolipids are recognised by cells of the immune system as 'self' or 'non-self'
- cell-to-cell recognition
- Cholesterol
- regulates fluidity of membranes
- prevents membrane from becoming too solid by stopping phospholipids from grouping too closely together
- adds stability to membranes
- hydrophilic end of cholesterol interacts with hydrophilic end of phospholipid and hydrophobic end of cholesterol interacts with hydrophobic end of phopholipid
- regulates fluidity of membranes
- Proteins
- Extrinsic - present in either layer of the membrane
- Intrinsic - embedded in both layers of the membrane
- Channel proteins
- involved in transport across membranes
- provide a hydrophilic channel that allows the passive movement of polar or charged moleclues
- Carrier proteins
- involved in transport across membranes
- change shape to help molecules pass through the membrane
- Channel proteins
- Phospholipid bilayer
- Factors affecting structure
- Temperature
- increase in temperature
- phospholipids gain more kinetic energy and move more
- membrane becomes more fluid and loses its structure
- proteins denature
- increased permeability
- phospholipids gain more kinetic energy and move more
- increase in temperature
- Solvents
- organic solvents, e.g. alcohol, are less polar than water
- they can cause the membrane to become more fluid and permeable
- very concentrated solvents can dissolve membranes
- organic solvents, e.g. alcohol, are less polar than water
- Temperature
- Structure and function
- increase in temperature
- phospholipids gain more kinetic energy and move more
- membrane becomes more fluid and loses its structure
- proteins denature
- increased permeability
- phospholipids gain more kinetic energy and move more
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