Question

The phospholipid bilayer describes a structure with:

a
b
ОООО
Polar heads on the outside and non-polar tails on the inside.
Non-polar tails on the outside and polar heads on the inside.
Polar layers on both the inside and outside.
Non-polar layers on both the inside and outside.
C

Answer 1

The phospholipid bilayer describes a structure with polar heads on the outside and non-polar tails on the inside (option a).

Step-by-step explanation:

The plasmatic membranes of the cells behave as a semi-permeable barrier to the passage of substances, a characteristic that depends on the hydrophobic properties of its phospholipid bilayer.

Lipidic bilayers are formed by the union of phospholipids with a hydrophobic —non-polar— head and a hydrophilic or polar tail, so they are called amphiphilic.

The bilayer phospholipids are arranged keeping the head —with a phosphate molecule— on the outside while the hydrophobic tails, formed by a double chain of fatty acids, on the inside.

The other options are not correct due to the explanation above:

• Non-polar tails on the outside and polar heads on the inside. The organization of the phospholipids does not admit this distribution of the molecule, which is observed when the phospholipids are in contact with water and form mycelium.
• Polar layers on both the inside and outside and non-polar layers on both the inside and outside are not possible, due to the molecular organization of the phospholipid.