What is the role of phospholipids in the cell membrane

Question 1

What is the structure of a cell membrane?

Answer 1

The structure of a cell membrane is composed of…

• 75% Phospholipids, the remainder being
• Proteins, cholesterol and polysaccharides

Question 2

phospholipid, protein, cholesterol, polysaccharide

Which is the key element of the cell surface membrane

Answer 2

• Phospholipid

Question 3

What is the structure of a phospholipid

Answer 3

A Phospholipid has

• 2 fatty acid chains and a phosphate group
• The Phosphate end of the phospholipid molecule is polar and therefore attracts other polar molecules e.g. water (Hydrophilic)
• The Lipid end of the phospholipid molecule is non polar, and therefore does not attract water (Hydrophobic)

Question 4

What happens when a phospho lipid comes into contact with water

Answer 4

• Hydrophilic heads are attracted to water and dip into it
• The hydrophobic tails move away from the water
• This forms a mono layer

Question 5

What 2 things happen if you shake up this mono layer

Answer 5

1. Phospholipids would form tiny spherical structures called micelles
2. The hydrophobic tails turn inwards and are protected by the hydrophilic head

Question 6

With respect the cell membrane…what 3 things can phospholipids form

Answer 6

1. Monolayers
2. Miceles
3. More importantly bi layers

Question 7

Why are Bi layers important

Answer 7

It forms the basis of the structure for the cell surface and other membranes

Question 8

What does a phospholipid by layer look like?

Answer 8

Question 10

What are the 5 reasons why phospholipids form the basis of cell membrane structure

Answer 10

1. Phospholipids can form bi layers
2. The inner phospholipid layer
   
   • Has its hydrophilic head pointing inwards towards the centre of the cell and interacts with the water in the cytoplasm
3. The outer phospholipid layer
   
   • Has its hydrophilic head pointing outwards interacting with the water surrounding the cell
4. The hydrophobic tails of the two phospholipid layers point towards each, other towards the centre of the membrane
5. The phospholipid component of a membrane allows lipid soluable molecules accross, but excludes water soluable molecules