Membrane Structure and Composition Flashcards
(28 cards)
what are three components of a membrane structure
glycoprotein, sterol, cytostolic leaflet
what do glycoproteins do
sorting signal and aid in stability
what do sterols do in membrane
maintain integrity of cell
what to cytostolic leaflets do in membrane
half of the phospholipid bilayer
what are the two parts of the phospholipid bilayer
cytostolic leaflet and extracellular leaflet
how is the lipid bilayer semi fluid
permits the movement of both lipids and proteins
what are some functions of the membranes
boundary/permeabiltiy barrier organization and localization transport signal detection cell-to-cell interactions
what are three components of the membrane
lipids, proteins, and carbohydrates
what are the types of sterols
low-density: bad kind
high-density: good kind
how is the membrane a fluid mosaic model
fluid: lipids and proteins can move
mosaic: made of many components; lipids, proteins, carbohydrates
what are phospholipids and what are different types
- the most abundant lipid in membranes
- glycerol-based and spingosine-based sphingolipids
- glycolipids: carbohydrate + lipid
what are fatty acids and what is their function
- they are essential to membrane structure and function
- components of all membrane lipids except sterols
- they are a barrier to diffusion of polar solutes
how do lipids move in their monolayer?
freely
- rotation and lateral diffusion (phospholipid)
- rapid and random movement
how is the membrane asymmetrical?
- lipids are distributed unequally between the 2 monolayers
- there are different kinds and varying degrees of saturation of the fatty acids in the phospholipids
what is freeze-fracture microscopy
a bilayer is frozen and then hit sharpely with a diamond kinfe to allow the plane between the 2 layers of membrane lipids to be visible
what state do membrane function in? what affects this state
fluid, changes with temperature
what is Tm? how is it affected
when the lipid becomes fluid
- disrupted when there is an increase in temperature; increases fluidity
what is diffusion
molecules move from high concentration to low concentration
what is osmosis
the movement of water across a semi permeable membrane (low to high solute concentration)
what is an electrochemical gradient
when there is a high concentration of a positively charged ion on the outside of the cell, negatively charged ions will be attracted to it
what are lipid rafts and how are they formed
- membrane microdomains that stay together as a unit
- need cholesterol and actin cytoskeleton
what are ion electrochemical gradients and what do they need
need ion pumps to transport ions across the gradient (require a lot of ATP)
what is passive transport and what does it require
powered by diffusion along chemical or electrochemical gradient
- requires channel proteins and transporter proteins
what is the difference between a chemical and electrochemical gradient
chemical: the difference of solute across a membrane
electrochemical: the difference of charge across a membrane
