Membranes Flashcards
What does a ski-permeable membrane allow?
chemical gradients to be maintained across the membranes
What do organelle membranes do?
They separate differing regions of biochemistry, and allow for the specialist function of the various components of the endomembrane system.
What is the structure of cholesterol?
A hydrophilic head and a hydrophobic tail. (Four ring steroid structure and non-polar side chain).
What is the function of cholesterol?
Reduces membrane fluidity and prevents lipid crystallisation at low temperatures.
What properties do peripheral (or extrinsic) proteins have?
Easily removed from membranes in the laboratory using ionic washes.
What holds the peripheral proteins in place?
Charged or polar amino acid R groups, or by a small number of hydrophobic interactions
What properties do Integral (intrinsic) proteins have?
They cannot be washed away from the membrane.
What holds integral proteins in place?
The strong hydrophobic interactions with the lipid tails
What is the name given to a protein which spans the entire length of the membrane?
Transmembrane
What is the name given to proteins and lipids which have carbohydrate chains added to them?
Glycoproteins or glycolipids
Where are the carbohydrate portion of glycolipids and glycoproteins found?
On the outside of the membrane
What are passive transport proteins?
Transmembrane proteins which transport molecules across a membrane down a concentration gradient.
What do channel proteins provide?
A pore that can facilitate or speed up diffusion
Give a detail of a channel protein
They are specific to one type of ion or molecule.
What do carrier proteins do?
They bind to a specific molecule to allow its passage
