Lipids

Question 1

Are the polar heads of phospholipids hydrophobic or hydrophilic?

Answer 1

Hydrophilic (loving water)

Question 2

Are the tails of phospholipids hydrophobic or hydrophilic?

Answer 2

Hydrophobic

Question 3

How do phospholipids orient themselves for membrane structure?

Answer 3

They orient themselves in a double layer with their hydrophobic tails facing the inside and the hydrophilic heads facing the aqueous environment on either side of the membrane

Question 4

How is the lipid bilateral selectively permeable?

Answer 4

Because of the hydrophobic interior, a lipid bilayer is readying permeable to nonpolar molecules. The exception is small uncharged molecules, regardless if they are polar (water and ethanol) or nonpolar (O2 and CO2)

Question 5

Can large uncharged molecules like glucose and sucrose diffuse across the membrane?

Answer 5

Yes but to a lesser extent than smaller ones

Question 6

What does a transport protein do?

Answer 6

Serves as a hydrophilic channel or carrier to transfer ions such as Na+ or K+ and polar molecules across membranes that are not permeable to these substances