3.1.1 Plasma Membrane (theory)
L.O: to label a plasma membrane
to explain the ‘fluid mosaic model’
Starter: Past exam questions on
centrifugation to recall info from last lesson
Structure
Function
Phospholipid
Allow lipid soluble substances to enter and
leave cell.
Prevent water soluble substances entering
and leaving.
Make the membrane flexible.
Allow large molecules and charged
molecules to pass through the plasma
membrane.
Certain molecules can bind to this and can
pass through into the cell.
Channel
protein
Carrier protein
Glycolipid and
Glycoprotein
Cholesterol
Cell recognition and interaction
(e.g. hormones can attach here)
Provide structural support / adds strength
L.O.2: Fluid Mosaic Model
Singer and Nicholson, 1972
Fluid =
Mosaic =
L.O.2: Fluid Mosaic Model
Singer and Nicholson, 1972
Fluid = individual phospholipids can move
around within their monolayer
Mosaic = the proteins create a mosaic type
pattern when viewed from above
•
•
•
•
1 Phosholipid consists of glycerol;
2 (To which are joined) two fatty acids;
3 And phosphate;
4 By condensation/elimination of water
molecules;
• 5 Arranged as bilayer in membrane;
• 6 Head/phosphate hydrophilic/polar and tail/fatty
acid hydrophobic/non-polar;
• 7 Heads outside and tails attracted to each
other/inside; max 6