Intrinsic Proteins Flashcards
Structure of Intrinsic protein.
Have amino acids with hydrophobic R-groups on their external surfaces which interact with hydrophobic core of membrane, keeping them in place.
4 types of intrinsic proteins.
Channel, Carrier, glycolipid and glycoprotein
How are channel proteins held in position?
By the interaction between the hydrophobic core of the membrane and the hydrophobic R groups on the outside of the protein.
What do channel proteins do?
They provide a hydrophilic channel in order for passive movement to occur of polar molecules/ions down a concentration gradient.
What is the role of the carrier proteins?
Have a role in passive transport, down the concentration gradient, and active transport, against the concentration gradient.
What does the carrier protein have to do in order to complete it’s role?
Change its shape.
Role of Glycoproteins
- Cell adhesion
- Act as receptors for chemical signals
What is cell signalling?
When a chemical binds to a receptor this evokes a response from the cell, the response may be direct or set of a cascade of events inside the cell.
Role of Glycolipids
- Antigens
- Recognised by cells of the immune system
What is cholesterol?
Lipid with hydrophobic and hydrophilic end.
Role of cholesterol
Regulates fluidity of membrane, adds to stability.
How does cholesterol add stability to membranes? (Without making it too rigid)
Are positioned in the bilayer so that the hydrophilic end interacts with phosphate head and the hydrophobic end interacts with the fatty acid tail, pulling them together without making them too rigid.
What happens if phospholipids molecules group too closely?
They crystallise. (become solid)
