Transport across cell membranes (BIOLOGY)(Chapter 4)
Briefly describe the structure of phospholipids
A phosphate head (hydrophilic) attached to two fatty acid tails (hydrophobic).
Name 3 functions of phospholipids
- Allow lipid-soluble substances to pass through
- Prevent water-soluble substances passing through
- Make the membrane flexible
Describe the placement of proteins in the phospholipid bilayer
- Some proteins occur on the surface and never extend fully across. They can give mechanical support to the membrane or as cell receptors in conjunction with glycolipids.
- Other proteins completely span the bilayer. I.e. protein channels and carrier proteins
Name 5 functions of proteins
- Structural support
- Channels to transport water-soluble substances
- Allow active transport to occur
- Form/act as receptors
- Help cell adhesion
Name the 5 components of the phospholipid bilayer
- Phospholipids
- Proteins (most common)
- Glycolipids
- Glycoproteins
- Cholesterol
Describe the 3 functions of cholesterol
- Reduce lateral movement of other components
- Reduce membrane fluidity at high temperatures
- Prevent leakage of water/dissolved ions
Name 3 functions of glycolipids
- Act as recognition sites
- Help maintain stability of the membrane
- Helps cells attach to each other
To what are carbohydrates attached to form glycoproteins?
Extrinsic proteins
Name 3 functions of glycoproteins
- Act as recognition sites
- Helps cells attach to each other
- Allows for cell recognition