Plasma Membranes Flashcards
What are the three main functions of plasma membranes?
Receive information, import and export molecules, capacity for movement and expansion
How thick is the plasma membrane?
5 nm
What are plasma membranes composed of?
Lipids and proteins
What is the key property of lipids??
They are amphipathic - have a hydrophilic head that faces outward to environment, and a hydrophobic tail that faces inward toward bilayer
What do pure phospholipids form in water?
Liposomes
What does fluidity of a membrane depend on?
Which phospholipids are present and the properties of the hydrocarbon tail (length/number of double carbon bonds)
What effect does double bonds have on fluidity of membrane?
Increases fluidity due to decreased packing
What effect does cholesterol have on membranes?
Increases the stiffness by filling in spaces of the membrane left by kinks of unsaturated hydrocarbon tail.
What are the three types of flip flop enzymes?
Flippases - move molecules from outside in.
Floppases - move molecules from inside out.
Scrambalases - move molecules in both directions.
What is the carbohydrate layer of the plasma membrane?
A layer of glycoproteins, that protects the cell from damage, prevents blood cells sticking to each other, involved in cell-cell communication and gives cell identity.
How is plasma membrane structure reinforced?
By the cell cortex. This is a transmembrane protein network, with the main protein being spectrin.
What are the two types of transport across a plasma membrane?
Passive or active transport.
What do anaesthetic drugs target?
They target the plasma membrane - bind to K+ and Cl- ion channels.
