T4:Transport across cell membranes Flashcards
How are phospholipids an important component for cell membranes?
-hydrophilic heads on the outside attracted by water
-hydrophobic tails in the centre which are repelled by water
What are the functions of the phospholipids in the membrane ?
-allow lipid soluble substances to enter/leave the cell
-prevent water soluble substances entering
-making the membrane flexible after self sealing
What are the functions of cholesterol in the membrane?
-add strength
-hydrophobic so they prevent water loss
-reduce lateral movement of molecules including phospholipids
-make membrane less fluid at high temperature
What are the functions of glycolipids in the membranes?
-acts as recognition sites
-help maintain the stability of the membrane
-help cells attach to one another and form tissues
Function of glycoproteins in bilayer?
-recognition sites
-helps cells attach to form tissues
-allows cells to recognise eachother
How are protein embedded in a bilayer?
-channel proteins span the layer ,water filled tubes to allow water soluble ions through
-carrier proteins (active transport) bind to ion ,change shape and carry across bilayer
Functions of protein in a bilayer?
-structural support
-allows water soluble ions through
-carrier proteins allow for active transport
-receptors
What is the fluid mosaic model?
fluid- phospholipids can move relative to eachother to provide flexibilty
mosaic-proteins embedded vary in shape and size like a mosaic
What is diffusion
-movement of particles from a place where there is a high concentration to a place where there is low concentration (DOWN conc. gradient)
How do carrier proteins carry out facilitated diffusion?
-molecule thats specific to protein then binds
-changes shape so its released to inside the membrane
How do proteins channels carry out facilitated diffusion?
-water filled hydrophilic channel cross membrane
-only opens at presence of specific water soluble ion
-bind to protein so it changes shape to close on one end and open at other
