Lecture 13 Membrane Structure Flashcards
What are the essential functions of biological membranes? (4) RCCS
Regulate the import/export of molecules.
Compartmentalize processes to increase efficiency.
Facilitate cell-cell recognition through glycoproteins and glycolipids.
Mediate signalling across the membrane using proteins and lipids.
what are cell membranes composed of?
lipid bilayers
what type of molecule characteristic makes the cell membrane and what interactions does it need to do this?
Formed by amphipathic molecules via non-covalent interactions.
what are cell membranes impermeable to?
polar or charged molecules.
what is membrane fluidity maintained by?
lipids and cholesterol
Why is membrane fluidity important? (2)
Enables movement of molecules and signals across the membrane.
Allows proteins to change conformation for function.
What do the terms “fluid” and “mosaic” mean in the Fluid Mosaic Model?
Describes membranes as fluid because components move within the membrane and mosaic referring to the mixture of lipids, proteins, and carbohydrates
who created the fluid mosaic model and when?
Proposed by Singer and Nicolson in the 1970s.
what does FRAP stand for?
Fluorescence Recovery After Photobleaching
what does FRAP measure?
measures molecule movement
describe the process of FRAP
A fluorophore is bleached with a laser, and the movement of unbleached molecules into the area is tracked
What does FRAP demonstrate about lipids and proteins?
Lipids and proteins move from side to side within the membrane.
What does FRAP demonstrate about lipid rafts?
Lipid rafts can restrict molecule movement.
What does FRAP demonstrate about protein diffusion?
depends on interactions with other proteins or the cytoskeleton.
What enzymes maintain membrane asymmetry?
Flippases, floppies, Scramblases
