Cell Surface Membrane Flashcards
What does the cell surface membrane control?
The exchange of materials between the internal cell environment and the external cell environment
How permeable is the cell surface membrane?
Partially permeable
What is the cell surface membrane formed from?
A phospholipid bilayer
What is the cell surface membrane made up of?
Hydrophilic head- glycerol and phosphate groups (polar)
Hydrophobic tails- 2 fatty acid chains (non-polar)
What do hydrophobic tails act as?
A barrier to soluble substances- ensures that water soluble molecules (sugars, amino acids and proteins) cannot leak out of the cell
The hydrophobic tails also allow what else to not get in?
Unwanted water-soluble molecules
The hydrophilic heads and hydrophobic tails can be chemically modified to act as?
Signallling molecules- by moving within the bilayer to activate other molecules e.g. enzymes
How can they also be chemically modified?
By being hydrolysed- which releases smaller water soluble molecules that bind to specific receptors in the cytoplasm
What do proteins do in the cell surface membrane?
Transport proteins create hydrophilic channels to allow ions and polar molecules to travel through the membrane
What do transport proteins also allow the cell to do?
Allows the cell to control what leaves and enters the cell
What are the 2 types of proteins?
Channel (pore) proteins
Carrier proteins
Each protein is specific to what?
A particular ion/molecule
What does cholesterol do in the membrane?
Regulates the fluidity of the membrane
Where do cholesterol molecules sit between and what does this prevent?
Sit between the phospholipids- prevents them from packing too closely together when temperatures are low- prevents membranes from freezing
What do glycolipids and glycoproteins contain?
Carbohydrate chains that exist on he surface of the cell- known as receptor molecules
