2.2.8 Phospholipids

Question 1

How does phospholipids differ than triglycerides?

Answer 1

• two fatty acid and one phosphate ion (PO43-)
• the phosphate ion is soluble (hydrophilic and polar)
• the fatty acids are non polar and insoluble
• this means phospholipids are amphipathic

Question 2

How is the bilayers in cell membranes formed?

Answer 2

Two rows of phospholipids are arranged with their hydrophilic heads in the watery solutions on either side of the membranes and their hydrophobic tails forming a layer this impermeable to hydrophilic substances

Question 3

List the function of phospholipids

Answer 3

1. Main component of cell membranes
2. Barrier to water-soluble molecules
3. Phosphate ions heads form H-bonds with the water allowing the cell to compartmentalize - enables cells to organize specific roles into organelles helping with efficiency
4. Contributes to the fluidity of the cell membrane: more saturated fatty acid –> less fluid; more unsaturated fatty acid –> more fluid
5. Phospholipids control membrane protein orientation- weak hydrophobic interactions between the phospholipids and membrane proteins hold the proteins but also allow for movement inside the layer