lipids and membranes Flashcards
How many molecules thick are membranes?
two
what are the major types of membrane lipid?
phospholipid
glycolipid
cholesterol
what are the features of membrane proteins?
- composed of the same 20 amino acids found in soluble proteins
- sometimes covalently attached to carbohydrate moieties
- sometimes covalently attached to lipid moiteties
- diffuse laterally in the membrane unless they’re anchored
what are membranes primarily comprised of?
lipids and proteins
how are peripheral membrane proteins bound in the membrane?
non covalently bound to membrane lipids
what increases the fluidity of lipid side chains in the interior of a bilayer?
an increase in the number of double bonds in fatty acids
what does the low incidence of protein or lipid flip flop in a membrane preserve?
membrane asymmetry
how many amino acid residues does the shortest α helix segment in a protein that will span a membrane bilayer have?
20
what complex is observed between cholesterol and membrane phospholipids?
lipid raft
What is the most common process by which lipids and proteins move in the membrane bilayer?
lateral diffusion
What helps to regulate membrane fluidity in animals?
cholesterol
what are the features of membrane lipids?
- many membranes are electrically polarised
- membrane lipids have both hydrophobic and hydrophilic properties
- membranes are lipid bilayers
what makes a membrane more fluid?
lipids that contain unsaturated fatty acids as the double bonds introduces kinks in the fatty acid chains which makes them more difficult to pack together.
What is a general feature of the lipid bilayer in all biological membranes?
individual lipid molecules are free to diffuse laterally in the surface of the bilayer.
What membrane components contain carbohydrates?
glycolipids
